<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019ef026-b4b1-72f2-9fd2-9502234479b2,g:fe1a821c-2e39-4c4a-b071-442890bd5a5c-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.usana.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="simple" xlink:href="usna-20260704.xsd#CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/CONDENSEDCONSOLIDATEDSTATEMENTSOFSTOCKHOLDERSEQUITY" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019ef026-b568-794e-af11-53215e268082" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019ef026-b568-72fd-b5ad-4c752ddfa954" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019ef026-b568-794e-af11-53215e268082" xlink:to="loc_us-gaap_StatementTable_019ef026-b568-72fd-b5ad-4c752ddfa954" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019ef026-b568-7371-99fc-6a345acc4242" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019ef026-b568-72fd-b5ad-4c752ddfa954" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019ef026-b568-7371-99fc-6a345acc4242" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019ef026-b568-7371-99fc-6a345acc4242_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019ef026-b568-7371-99fc-6a345acc4242" xlink:to="loc_us-gaap_EquityComponentDomain_019ef026-b568-7371-99fc-6a345acc4242_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019ef026-b568-77c0-bcf4-dc1d515d4431" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019ef026-b568-7371-99fc-6a345acc4242" xlink:to="loc_us-gaap_EquityComponentDomain_019ef026-b568-77c0-bcf4-dc1d515d4431" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019ef026-b568-70b9-87f5-f7a250e0802c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019ef026-b568-77c0-bcf4-dc1d515d4431" xlink:to="loc_us-gaap_CommonStockMember_019ef026-b568-70b9-87f5-f7a250e0802c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019ef026-b568-75af-8a63-2ceab729a2df" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019ef026-b568-77c0-bcf4-dc1d515d4431" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019ef026-b568-75af-8a63-2ceab729a2df" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019ef026-b568-7323-9a01-b3812010fcc6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019ef026-b568-77c0-bcf4-dc1d515d4431" xlink:to="loc_us-gaap_RetainedEarningsMember_019ef026-b568-7323-9a01-b3812010fcc6" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019ef026-b568-7b3e-be4a-cd4bffb5a82a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019ef026-b568-77c0-bcf4-dc1d515d4431" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019ef026-b568-7b3e-be4a-cd4bffb5a82a" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019ef026-b568-76d0-9809-c9b16cffa595" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019ef026-b568-794e-af11-53215e268082" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019ef026-b568-76d0-9809-c9b16cffa595" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019ef026-b568-7f4f-a6eb-06bc94a8668e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019ef026-b568-76d0-9809-c9b16cffa595" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019ef026-b568-7f4f-a6eb-06bc94a8668e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019ef026-b568-7071-8a75-efd15385861f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019ef026-b568-76d0-9809-c9b16cffa595" xlink:to="loc_us-gaap_StockholdersEquity_019ef026-b568-7071-8a75-efd15385861f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019ef026-b568-7978-9571-19ce62a86846" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019ef026-b568-76d0-9809-c9b16cffa595" xlink:to="loc_us-gaap_NetIncomeLoss_019ef026-b568-7978-9571-19ce62a86846" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019ef026-b568-74ee-a42b-9b0b107a5287" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019ef026-b568-76d0-9809-c9b16cffa595" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019ef026-b568-74ee-a42b-9b0b107a5287" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019ef026-b568-7eaa-85a1-cb315e0b2183" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019ef026-b568-76d0-9809-c9b16cffa595" xlink:to="loc_us-gaap_AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue_019ef026-b568-7eaa-85a1-cb315e0b2183" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019ef026-b568-72b6-810f-38eb24646b3f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019ef026-b568-76d0-9809-c9b16cffa595" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodShares_019ef026-b568-72b6-810f-38eb24646b3f" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019ef026-b568-7224-941d-cadddc877d5e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockRepurchasedAndRetiredDuringPeriodValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019ef026-b568-76d0-9809-c9b16cffa595" xlink:to="loc_us-gaap_StockRepurchasedAndRetiredDuringPeriodValue_019ef026-b568-7224-941d-cadddc877d5e" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019ef026-b568-7fb3-afcb-3a49357e3a98" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019ef026-b568-76d0-9809-c9b16cffa595" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019ef026-b568-7fb3-afcb-3a49357e3a98" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019ef026-b568-7a8b-934a-864728914adb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019ef026-b568-76d0-9809-c9b16cffa595" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019ef026-b568-7a8b-934a-864728914adb" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019ef026-b568-791c-89a1-e09680e4525d" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019ef026-b568-76d0-9809-c9b16cffa595" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019ef026-b568-791c-89a1-e09680e4525d" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019ef026-b568-7fc3-b3a9-c9ce9878e634" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019ef026-b568-717e-8608-28a69d232593" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/ORGANIZATIONCONSOLIDATIONANDBASISOFPRESENTATIONDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#ORGANIZATIONCONSOLIDATIONANDBASISOFPRESENTATIONDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/ORGANIZATIONCONSOLIDATIONANDBASISOFPRESENTATIONDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019ef026-b569-79a2-903a-7d22a207adaa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019ef026-b569-7cfb-8c5f-fbb3a6934841" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019ef026-b569-79a2-903a-7d22a207adaa" xlink:to="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019ef026-b569-7cfb-8c5f-fbb3a6934841" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019ef026-b569-7287-bba0-65c171b711f5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019ef026-b569-7cfb-8c5f-fbb3a6934841" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019ef026-b569-7287-bba0-65c171b711f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019ef026-b569-7287-bba0-65c171b711f5_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019ef026-b569-7287-bba0-65c171b711f5" xlink:to="loc_us-gaap_SegmentDomain_019ef026-b569-7287-bba0-65c171b711f5_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019ef026-b569-7cf1-a84a-9563158ba013" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019ef026-b569-7287-bba0-65c171b711f5" xlink:to="loc_us-gaap_SegmentDomain_019ef026-b569-7cf1-a84a-9563158ba013" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_CoreNutritionalMember_019ef026-b569-7b27-b8da-fcdeb0a7f0fe" xlink:href="usna-20260704.xsd#usna_CoreNutritionalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019ef026-b569-7cf1-a84a-9563158ba013" xlink:to="loc_usna_CoreNutritionalMember_019ef026-b569-7b27-b8da-fcdeb0a7f0fe" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019ef026-b569-7b9e-b73c-f66b3068020f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfCollaborativeArrangementsAndNoncollaborativeArrangementTransactionsTable_019ef026-b569-7cfb-8c5f-fbb3a6934841" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019ef026-b569-7b9e-b73c-f66b3068020f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019ef026-b569-7b9e-b73c-f66b3068020f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019ef026-b569-7b9e-b73c-f66b3068020f" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019ef026-b569-7b9e-b73c-f66b3068020f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019ef026-b569-7a51-ad24-1c725c55ad8a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019ef026-b569-7b9e-b73c-f66b3068020f" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019ef026-b569-7a51-ad24-1c725c55ad8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_HiyaMember_019ef026-b569-70bd-ba8e-42e7a339d133" xlink:href="usna-20260704.xsd#usna_HiyaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019ef026-b569-7a51-ad24-1c725c55ad8a" xlink:to="loc_usna_HiyaMember_019ef026-b569-70bd-ba8e-42e7a339d133" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfOperatingSegments_019ef026-b569-7aea-a679-80b4c3cfc156" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfOperatingSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019ef026-b569-79a2-903a-7d22a207adaa" xlink:to="loc_us-gaap_NumberOfOperatingSegments_019ef026-b569-7aea-a679-80b4c3cfc156" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NumberOfReportableSegments_019ef026-b569-7037-a4ad-75d2afbcd6d3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NumberOfReportableSegments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019ef026-b569-79a2-903a-7d22a207adaa" xlink:to="loc_us-gaap_NumberOfReportableSegments_019ef026-b569-7037-a4ad-75d2afbcd6d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_ReportableSegmentPercentageOfConsolidatedNetSales_019ef026-b569-7937-9702-453da67e62c7" xlink:href="usna-20260704.xsd#usna_ReportableSegmentPercentageOfConsolidatedNetSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019ef026-b569-79a2-903a-7d22a207adaa" xlink:to="loc_usna_ReportableSegmentPercentageOfConsolidatedNetSales_019ef026-b569-7937-9702-453da67e62c7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_NumberOfGeographicRegions_019ef026-b569-720b-8ecd-afba0b97f04e" xlink:href="usna-20260704.xsd#usna_NumberOfGeographicRegions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019ef026-b569-79a2-903a-7d22a207adaa" xlink:to="loc_usna_NumberOfGeographicRegions_019ef026-b569-720b-8ecd-afba0b97f04e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_NumberOfSubGeographicalRegions_019ef026-b569-7e9c-808e-2eb4fb6a0192" xlink:href="usna-20260704.xsd#usna_NumberOfSubGeographicalRegions"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019ef026-b569-79a2-903a-7d22a207adaa" xlink:to="loc_usna_NumberOfSubGeographicalRegions_019ef026-b569-7e9c-808e-2eb4fb6a0192" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_019ef026-b569-72aa-b42f-6691a48cccad" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CollaborativeArrangementsAndNoncollaborativeArrangementTransactionsLineItems_019ef026-b569-79a2-903a-7d22a207adaa" xlink:to="loc_us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired_019ef026-b569-72aa-b42f-6691a48cccad" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/FAIRVALUEMEASURESScheduleOfAssetsAndLiabilitiesMeasuredAtFairValueDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#FAIRVALUEMEASURESScheduleOfAssetsAndLiabilitiesMeasuredAtFairValueDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/FAIRVALUEMEASURESScheduleOfAssetsAndLiabilitiesMeasuredAtFairValueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019ef026-b569-76a0-afa9-3a3dc8b717a2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019ef026-b569-7456-8074-f27ab6cd91e8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019ef026-b569-76a0-afa9-3a3dc8b717a2" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019ef026-b569-7456-8074-f27ab6cd91e8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsAxis_019ef026-b569-7a93-81df-8d1dfa8a0cfa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019ef026-b569-7456-8074-f27ab6cd91e8" xlink:to="loc_us-gaap_CashAndCashEquivalentsAxis_019ef026-b569-7a93-81df-8d1dfa8a0cfa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019ef026-b569-7a93-81df-8d1dfa8a0cfa_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_019ef026-b569-7a93-81df-8d1dfa8a0cfa" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019ef026-b569-7a93-81df-8d1dfa8a0cfa_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019ef026-b569-7c36-9640-2322d5f5ac19" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CashAndCashEquivalentsAxis_019ef026-b569-7a93-81df-8d1dfa8a0cfa" xlink:to="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019ef026-b569-7c36-9640-2322d5f5ac19" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MoneyMarketFundsMember_019ef026-b569-734d-bec6-7748ad94e0e2" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_MoneyMarketFundsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestrictedCashAndCashEquivalentsCashAndCashEquivalentsMember_019ef026-b569-7c36-9640-2322d5f5ac19" xlink:to="loc_us-gaap_MoneyMarketFundsMember_019ef026-b569-734d-bec6-7748ad94e0e2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019ef026-b569-785b-a47d-b6229a26efdd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019ef026-b569-7456-8074-f27ab6cd91e8" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019ef026-b569-785b-a47d-b6229a26efdd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef026-b569-785b-a47d-b6229a26efdd_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019ef026-b569-785b-a47d-b6229a26efdd" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef026-b569-785b-a47d-b6229a26efdd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef026-b569-774f-8d6d-cb176192b70f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019ef026-b569-785b-a47d-b6229a26efdd" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef026-b569-774f-8d6d-cb176192b70f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019ef026-b569-7d16-9344-4afc592306c6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef026-b569-774f-8d6d-cb176192b70f" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019ef026-b569-7d16-9344-4afc592306c6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019ef026-b569-7635-aca5-878d3769569a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef026-b569-774f-8d6d-cb176192b70f" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019ef026-b569-7635-aca5-878d3769569a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019ef026-b569-7076-ad3a-f7d13be78b69" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019ef026-b569-774f-8d6d-cb176192b70f" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019ef026-b569-7076-ad3a-f7d13be78b69" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019ef026-b569-7790-97d7-d26442f6b355" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019ef026-b569-76a0-afa9-3a3dc8b717a2" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019ef026-b569-7790-97d7-d26442f6b355" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_019ef026-b569-77f7-896c-74d9679fdceb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019ef026-b569-76a0-afa9-3a3dc8b717a2" xlink:to="loc_us-gaap_ForeignCurrencyContractsLiabilityFairValueDisclosure_019ef026-b569-77f7-896c-74d9679fdceb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_019ef026-b569-7bf3-9c66-d19ad1666d48" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019ef026-b569-76a0-afa9-3a3dc8b717a2" xlink:to="loc_us-gaap_DeferredCompensationLiabilityClassifiedNoncurrent_019ef026-b569-7bf3-9c66-d19ad1666d48" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/GOODWILLChangesinCarryingAmountsofGoodwillDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#GOODWILLChangesinCarryingAmountsofGoodwillDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/GOODWILLChangesinCarryingAmountsofGoodwillDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillLineItems_019fd091-a538-79e8-a301-cd9f5bed8844" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfGoodwillTable_019fd091-a538-7e96-abd6-b2901bcd69fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfGoodwillTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_GoodwillLineItems_019fd091-a538-79e8-a301-cd9f5bed8844" xlink:to="loc_us-gaap_ScheduleOfGoodwillTable_019fd091-a538-7e96-abd6-b2901bcd69fe" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019fd091-a538-7ad9-9526-8799450d4c14" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfGoodwillTable_019fd091-a538-7e96-abd6-b2901bcd69fe" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019fd091-a538-7ad9-9526-8799450d4c14" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fd091-a538-7ad9-9526-8799450d4c14_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019fd091-a538-7ad9-9526-8799450d4c14" xlink:to="loc_us-gaap_SegmentDomain_019fd091-a538-7ad9-9526-8799450d4c14_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019fd091-a538-79a9-968c-41c30cfda35a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019fd091-a538-7ad9-9526-8799450d4c14" xlink:to="loc_us-gaap_SegmentDomain_019fd091-a538-79a9-968c-41c30cfda35a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_CoreNutritionalMember_019fd091-a538-7786-8fcd-7dfcd4bf9323" xlink:href="usna-20260704.xsd#usna_CoreNutritionalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fd091-a538-79a9-968c-41c30cfda35a" xlink:to="loc_usna_CoreNutritionalMember_019fd091-a538-7786-8fcd-7dfcd4bf9323" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_HiyaMember_019fd091-a538-7efc-8a32-20222f283289" xlink:href="usna-20260704.xsd#usna_HiyaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fd091-a538-79a9-968c-41c30cfda35a" xlink:to="loc_usna_HiyaMember_019fd091-a538-7efc-8a32-20222f283289" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_RiseMember_019fd091-a538-7b8a-9784-117f50fa59d1" xlink:href="usna-20260704.xsd#usna_RiseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019fd091-a538-79a9-968c-41c30cfda35a" xlink:to="loc_usna_RiseMember_019fd091-a538-7b8a-9784-117f50fa59d1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillGross_019fd091-a538-7a64-8bbe-bd91c551b488" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019fd091-a538-79e8-a301-cd9f5bed8844" xlink:to="loc_us-gaap_GoodwillGross_019fd091-a538-7a64-8bbe-bd91c551b488" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_019fd091-a538-7e5d-8db4-565d4a44d616" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillImpairedAccumulatedImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019fd091-a538-79e8-a301-cd9f5bed8844" xlink:to="loc_us-gaap_GoodwillImpairedAccumulatedImpairmentLoss_019fd091-a538-7e5d-8db4-565d4a44d616" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019fd091-a538-7a50-a344-b1ffb010c245" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019fd091-a538-79e8-a301-cd9f5bed8844" xlink:to="loc_us-gaap_Goodwill_019fd091-a538-7a50-a344-b1ffb010c245" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_019fd091-a538-7f3c-b610-c52779309a31" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019fd091-a538-79e8-a301-cd9f5bed8844" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_019fd091-a538-7f3c-b610-c52779309a31" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_019fd091-a538-744e-914c-a0f5d9e25a2a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillForeignCurrencyTranslationGainLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GoodwillLineItems_019fd091-a538-79e8-a301-cd9f5bed8844" xlink:to="loc_us-gaap_GoodwillForeignCurrencyTranslationGainLoss_019fd091-a538-744e-914c-a0f5d9e25a2a" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/INVENTORIESNarrativeDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#INVENTORIESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/INVENTORIESNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryLineItems_019ef026-b569-7654-b929-d1dfd665c155" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryCurrentTable_019ef026-b569-7878-b084-020750305d62" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryCurrentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_InventoryLineItems_019ef026-b569-7654-b929-d1dfd665c155" xlink:to="loc_us-gaap_InventoryCurrentTable_019ef026-b569-7878-b084-020750305d62" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryAxis_019ef026-b569-79b4-bb5b-ab4085a1f31f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesInventoryAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_InventoryCurrentTable_019ef026-b569-7878-b084-020750305d62" xlink:to="loc_us-gaap_PublicUtilitiesInventoryAxis_019ef026-b569-79b4-bb5b-ab4085a1f31f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_019ef026-b569-79b4-bb5b-ab4085a1f31f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_019ef026-b569-79b4-bb5b-ab4085a1f31f" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_019ef026-b569-79b4-bb5b-ab4085a1f31f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_019ef026-b569-75e7-9725-65dba0221392" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesInventoryTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PublicUtilitiesInventoryAxis_019ef026-b569-79b4-bb5b-ab4085a1f31f" xlink:to="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_019ef026-b569-75e7-9725-65dba0221392" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PublicUtilitiesInventoryRawMaterialsMember_019ef026-b569-71b1-a92e-a5b1d3112e67" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_PublicUtilitiesInventoryRawMaterialsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_019ef026-b569-75e7-9725-65dba0221392" xlink:to="loc_us-gaap_PublicUtilitiesInventoryRawMaterialsMember_019ef026-b569-71b1-a92e-a5b1d3112e67" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_FinishedGoodsMember_019ef026-b569-7199-a027-6d82cbc65e87" xlink:href="usna-20260704.xsd#usna_FinishedGoodsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PublicUtilitiesInventoryTypeDomain_019ef026-b569-75e7-9725-65dba0221392" xlink:to="loc_usna_FinishedGoodsMember_019ef026-b569-7199-a027-6d82cbc65e87" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InventoryNoncurrent_019ef026-b569-7363-84cf-ea4d2930316b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InventoryNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_InventoryLineItems_019ef026-b569-7654-b929-d1dfd665c155" xlink:to="loc_us-gaap_InventoryNoncurrent_019ef026-b569-7363-84cf-ea4d2930316b" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/REVENUEANDCONTRACTLIABILITIESNarrativeDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#REVENUEANDCONTRACTLIABILITIESNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/REVENUEANDCONTRACTLIABILITIESNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019ef026-b569-76e3-bb48-438c4037cf13" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019ef026-b569-79c8-bfcd-aeade1b37336" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019ef026-b569-76e3-bb48-438c4037cf13" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019ef026-b569-79c8-bfcd-aeade1b37336" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MajorCustomersAxis_019ef026-b569-71c5-9eee-d1d4b01d83ac" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_MajorCustomersAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019ef026-b569-79c8-bfcd-aeade1b37336" xlink:to="loc_srt_MajorCustomersAxis_019ef026-b569-71c5-9eee-d1d4b01d83ac" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019ef026-b569-71c5-9eee-d1d4b01d83ac_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_MajorCustomersAxis_019ef026-b569-71c5-9eee-d1d4b01d83ac" xlink:to="loc_srt_NameOfMajorCustomerDomain_019ef026-b569-71c5-9eee-d1d4b01d83ac_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_NameOfMajorCustomerDomain_019ef026-b569-7362-ad08-d663431e2e93" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_NameOfMajorCustomerDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_MajorCustomersAxis_019ef026-b569-71c5-9eee-d1d4b01d83ac" xlink:to="loc_srt_NameOfMajorCustomerDomain_019ef026-b569-7362-ad08-d663431e2e93" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_CustomerOneMember_019ef026-b569-7b22-9e6f-ce1784c91de5" xlink:href="usna-20260704.xsd#usna_CustomerOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019ef026-b569-7362-ad08-d663431e2e93" xlink:to="loc_usna_CustomerOneMember_019ef026-b569-7b22-9e6f-ce1784c91de5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_CustomerTwoMember_019fefa8-ce62-74d3-91df-7456108bbc0c" xlink:href="usna-20260704.xsd#usna_CustomerTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_NameOfMajorCustomerDomain_019ef026-b569-7362-ad08-d663431e2e93" xlink:to="loc_usna_CustomerTwoMember_019fefa8-ce62-74d3-91df-7456108bbc0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019ef026-b569-7fa9-b7c9-e47ba6959861" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019ef026-b569-79c8-bfcd-aeade1b37336" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019ef026-b569-7fa9-b7c9-e47ba6959861" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef026-b569-7fa9-b7c9-e47ba6959861_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019ef026-b569-7fa9-b7c9-e47ba6959861" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef026-b569-7fa9-b7c9-e47ba6959861_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef026-b569-79be-bf4c-0455063b3635" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019ef026-b569-7fa9-b7c9-e47ba6959861" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef026-b569-79be-bf4c-0455063b3635" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TradeAccountsReceivableMember_019ef026-b569-788b-a397-429504801ce1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_TradeAccountsReceivableMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef026-b569-79be-bf4c-0455063b3635" xlink:to="loc_us-gaap_TradeAccountsReceivableMember_019ef026-b569-788b-a397-429504801ce1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019ef026-b569-7fdc-85d9-e387a1bc006b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019ef026-b569-79c8-bfcd-aeade1b37336" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019ef026-b569-7fdc-85d9-e387a1bc006b" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019ef026-b569-7fdc-85d9-e387a1bc006b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019ef026-b569-7fdc-85d9-e387a1bc006b" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019ef026-b569-7fdc-85d9-e387a1bc006b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019ef026-b569-7a8d-b912-ff1289641c94" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019ef026-b569-7fdc-85d9-e387a1bc006b" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019ef026-b569-7a8d-b912-ff1289641c94" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerConcentrationRiskMember_019ef026-b569-771b-b1a1-6c00d2d4757f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CustomerConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019ef026-b569-7a8d-b912-ff1289641c94" xlink:to="loc_us-gaap_CustomerConcentrationRiskMember_019ef026-b569-771b-b1a1-6c00d2d4757f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019ef026-b569-70ae-804e-a71092c47e25" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019ef026-b569-76e3-bb48-438c4037cf13" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019ef026-b569-70ae-804e-a71092c47e25" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/LINEOFCREDITDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#LINEOFCREDITDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/LINEOFCREDITDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityLineItems_019ef026-b569-7367-bf89-e1c42432d736" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityTable_019ef026-b569-755f-8e1a-7e7229fb8546" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019ef026-b569-7367-bf89-e1c42432d736" xlink:to="loc_us-gaap_LineOfCreditFacilityTable_019ef026-b569-755f-8e1a-7e7229fb8546" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019ef026-b569-7a26-ac58-27b25f4146e4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019ef026-b569-755f-8e1a-7e7229fb8546" xlink:to="loc_us-gaap_CreditFacilityAxis_019ef026-b569-7a26-ac58-27b25f4146e4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019ef026-b569-7a26-ac58-27b25f4146e4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019ef026-b569-7a26-ac58-27b25f4146e4" xlink:to="loc_us-gaap_CreditFacilityDomain_019ef026-b569-7a26-ac58-27b25f4146e4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019ef026-b569-740c-9381-a6f0d52d1b8c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019ef026-b569-7a26-ac58-27b25f4146e4" xlink:to="loc_us-gaap_CreditFacilityDomain_019ef026-b569-740c-9381-a6f0d52d1b8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019ef026-b569-7430-9887-9a24a2145eb7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019ef026-b569-740c-9381-a6f0d52d1b8c" xlink:to="loc_us-gaap_LineOfCreditMember_019ef026-b569-7430-9887-9a24a2145eb7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019ef026-b569-71b5-939f-3c56a871c723" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019ef026-b569-755f-8e1a-7e7229fb8546" xlink:to="loc_us-gaap_DebtInstrumentAxis_019ef026-b569-71b5-939f-3c56a871c723" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019ef026-b569-71b5-939f-3c56a871c723_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019ef026-b569-71b5-939f-3c56a871c723" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019ef026-b569-71b5-939f-3c56a871c723_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019ef026-b569-73a7-89cb-cab95b833ccd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019ef026-b569-71b5-939f-3c56a871c723" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019ef026-b569-73a7-89cb-cab95b833ccd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_CreditAgreementMember_019ef026-b569-7118-9191-19170d2c4cbf" xlink:href="usna-20260704.xsd#usna_CreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019ef026-b569-73a7-89cb-cab95b833ccd" xlink:to="loc_usna_CreditAgreementMember_019ef026-b569-7118-9191-19170d2c4cbf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_AmendedAndRestatedCreditAgreementMember_019ef026-b569-7ae5-aa07-0fb85f0157a3" xlink:href="usna-20260704.xsd#usna_AmendedAndRestatedCreditAgreementMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019ef026-b569-73a7-89cb-cab95b833ccd" xlink:to="loc_usna_AmendedAndRestatedCreditAgreementMember_019ef026-b569-7ae5-aa07-0fb85f0157a3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_LocalLineOfCreditMember_019fdca2-150d-7658-b4cc-b74ac2feb2cd" xlink:href="usna-20260704.xsd#usna_LocalLineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019ef026-b569-73a7-89cb-cab95b833ccd" xlink:to="loc_usna_LocalLineOfCreditMember_019fdca2-150d-7658-b4cc-b74ac2feb2cd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019ef026-b569-7cc9-b326-33ae5af43482" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LineOfCreditFacilityTable_019ef026-b569-755f-8e1a-7e7229fb8546" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019ef026-b569-7cc9-b326-33ae5af43482" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019ef026-b569-7cc9-b326-33ae5af43482_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019ef026-b569-7cc9-b326-33ae5af43482" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019ef026-b569-7cc9-b326-33ae5af43482_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019ef026-b569-7165-b97d-a43ff49a8512" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019ef026-b569-7cc9-b326-33ae5af43482" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019ef026-b569-7165-b97d-a43ff49a8512" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_019ef026-b569-7ac1-9984-907706e7c27a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019ef026-b569-7165-b97d-a43ff49a8512" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_019ef026-b569-7ac1-9984-907706e7c27a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_019ef026-b569-7469-9193-1b84b45cb6fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019ef026-b569-7165-b97d-a43ff49a8512" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_019ef026-b569-7469-9193-1b84b45cb6fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019ef026-b569-7d22-874d-862131fda933" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019ef026-b569-7367-bf89-e1c42432d736" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019ef026-b569-7d22-874d-862131fda933" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_LineOfCreditFacilityAdditionalIncreaseInMaximumBorrowingCapacity_019ef026-b569-76df-8a33-2508a5c2319f" xlink:href="usna-20260704.xsd#usna_LineOfCreditFacilityAdditionalIncreaseInMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019ef026-b569-7367-bf89-e1c42432d736" xlink:to="loc_usna_LineOfCreditFacilityAdditionalIncreaseInMaximumBorrowingCapacity_019ef026-b569-76df-8a33-2508a5c2319f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LinesOfCreditCurrent_019ef026-b569-7f22-b6cf-71b54b1fc261" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_LinesOfCreditCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019ef026-b569-7367-bf89-e1c42432d736" xlink:to="loc_us-gaap_LinesOfCreditCurrent_019ef026-b569-7f22-b6cf-71b54b1fc261" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_DebtInstrumentCovenantAdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization_019ef026-b569-79d2-875a-cfa1b8a9051e" xlink:href="usna-20260704.xsd#usna_DebtInstrumentCovenantAdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019ef026-b569-7367-bf89-e1c42432d736" xlink:to="loc_usna_DebtInstrumentCovenantAdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization_019ef026-b569-79d2-875a-cfa1b8a9051e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_DebtInstrumentCovenantRatioOfConsolidatedFundedDebtToAdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization_019ef026-b569-79fb-bddf-fabaea00184b" xlink:href="usna-20260704.xsd#usna_DebtInstrumentCovenantRatioOfConsolidatedFundedDebtToAdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LineOfCreditFacilityLineItems_019ef026-b569-7367-bf89-e1c42432d736" xlink:to="loc_usna_DebtInstrumentCovenantRatioOfConsolidatedFundedDebtToAdjustedEarningsBeforeInterestTaxesDepreciationAndAmortization_019ef026-b569-79fb-bddf-fabaea00184b" xlink:type="arc" order="4"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/DERIVATIVEFINANCIALINSTRUMENTSDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#DERIVATIVEFINANCIALINSTRUMENTSDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/DERIVATIVEFINANCIALINSTRUMENTSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeLineItems_019ef026-b569-71d1-a646-bb2639ee84a0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeTable_019ef026-b569-7ab9-a8c7-f0cf8231e809" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DerivativeLineItems_019ef026-b569-71d1-a646-bb2639ee84a0" xlink:to="loc_us-gaap_DerivativeTable_019ef026-b569-7ab9-a8c7-f0cf8231e809" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019ef026-b569-74dc-8aee-a18e6231b3a7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019ef026-b569-7ab9-a8c7-f0cf8231e809" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019ef026-b569-74dc-8aee-a18e6231b3a7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019ef026-b569-74dc-8aee-a18e6231b3a7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019ef026-b569-74dc-8aee-a18e6231b3a7" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019ef026-b569-74dc-8aee-a18e6231b3a7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019ef026-b569-7c2b-b4da-f8a1dea091ff" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019ef026-b569-74dc-8aee-a18e6231b3a7" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019ef026-b569-7c2b-b4da-f8a1dea091ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeOptionMember_019ef026-b569-7f89-94f7-e4d809d7c079" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ForeignExchangeOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019ef026-b569-7c2b-b4da-f8a1dea091ff" xlink:to="loc_us-gaap_ForeignExchangeOptionMember_019ef026-b569-7f89-94f7-e4d809d7c079" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019ef026-b569-7636-bdb5-fb0886a4a73f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019ef026-b569-7ab9-a8c7-f0cf8231e809" xlink:to="loc_us-gaap_HedgingDesignationAxis_019ef026-b569-7636-bdb5-fb0886a4a73f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019ef026-b569-7636-bdb5-fb0886a4a73f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019ef026-b569-7636-bdb5-fb0886a4a73f" xlink:to="loc_us-gaap_HedgingDesignationDomain_019ef026-b569-7636-bdb5-fb0886a4a73f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019ef026-b569-7ac2-ad81-857ce80c00b0" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019ef026-b569-7636-bdb5-fb0886a4a73f" xlink:to="loc_us-gaap_HedgingDesignationDomain_019ef026-b569-7ac2-ad81-857ce80c00b0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019ef026-b569-7f51-83ba-34a28bc330b3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019ef026-b569-7ac2-ad81-857ce80c00b0" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019ef026-b569-7f51-83ba-34a28bc330b3" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019ef026-b569-7b9d-ae9a-072bf20f674e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DerivativeTable_019ef026-b569-7ab9-a8c7-f0cf8231e809" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019ef026-b569-7b9d-ae9a-072bf20f674e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019ef026-b569-7b9d-ae9a-072bf20f674e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019ef026-b569-7b9d-ae9a-072bf20f674e" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019ef026-b569-7b9d-ae9a-072bf20f674e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019ef026-b569-709a-9449-859680616d54" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019ef026-b569-7b9d-ae9a-072bf20f674e" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019ef026-b569-709a-9449-859680616d54" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019ef026-b569-7224-82a1-a3464a555bdc" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019ef026-b569-709a-9449-859680616d54" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019ef026-b569-7224-82a1-a3464a555bdc" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019ef026-b569-7d23-a872-d0ef23f5fcdd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019ef026-b569-71d1-a646-bb2639ee84a0" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019ef026-b569-7d23-a872-d0ef23f5fcdd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnrealizedGainLossOnDerivatives_019ef026-b569-795c-a4e8-ef0aaadef6e3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_UnrealizedGainLossOnDerivatives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeLineItems_019ef026-b569-71d1-a646-bb2639ee84a0" xlink:to="loc_us-gaap_UnrealizedGainLossOnDerivatives_019ef026-b569-795c-a4e8-ef0aaadef6e3" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/COMMONSTOCKANDEARNINGSPERSHAREScheduleofEarningsPerShareDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#COMMONSTOCKANDEARNINGSPERSHAREScheduleofEarningsPerShareDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/COMMONSTOCKANDEARNINGSPERSHAREScheduleofEarningsPerShareDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fcd47-b0e6-761f-bda0-f126ec62d589" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019fcd47-b0e6-7cf0-98fd-4ef3f030ce83" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fcd47-b0e6-761f-bda0-f126ec62d589" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019fcd47-b0e6-7cf0-98fd-4ef3f030ce83" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019fcd47-b0e6-759d-a103-69146e12f100" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019fcd47-b0e6-7cf0-98fd-4ef3f030ce83" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019fcd47-b0e6-759d-a103-69146e12f100" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fcd47-b0e6-759d-a103-69146e12f100_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019fcd47-b0e6-759d-a103-69146e12f100" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fcd47-b0e6-759d-a103-69146e12f100_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fcd47-b0e6-7f4b-8a4b-ec1b67e67939" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019fcd47-b0e6-759d-a103-69146e12f100" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fcd47-b0e6-7f4b-8a4b-ec1b67e67939" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockCompensationPlanMember_019fcd48-41df-7dc9-8f91-5757391ec99c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StockCompensationPlanMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019fcd47-b0e6-7f4b-8a4b-ec1b67e67939" xlink:to="loc_us-gaap_StockCompensationPlanMember_019fcd48-41df-7dc9-8f91-5757391ec99c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019ef026-b569-7470-8e44-5d17a6856ec7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fcd47-b0e6-761f-bda0-f126ec62d589" xlink:to="loc_us-gaap_NetIncomeLoss_019ef026-b569-7470-8e44-5d17a6856ec7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019ef026-b569-76f1-b16f-a80c44b588e5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fcd47-b0e6-761f-bda0-f126ec62d589" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019ef026-b569-76f1-b16f-a80c44b588e5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019ef026-b569-7568-a3e5-072a78c0bb9c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fcd47-b0e6-761f-bda0-f126ec62d589" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019ef026-b569-7568-a3e5-072a78c0bb9c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019ef026-b569-7f7d-aa8a-a4ef6dbca425" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fcd47-b0e6-761f-bda0-f126ec62d589" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019ef026-b569-7f7d-aa8a-a4ef6dbca425" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasicAbstract_019ef026-b569-778e-95c5-5d5f4c590806" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasicAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fcd47-b0e6-761f-bda0-f126ec62d589" xlink:to="loc_us-gaap_EarningsPerShareBasicAbstract_019ef026-b569-778e-95c5-5d5f4c590806" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019ef026-b569-78d7-a945-f9d088c1d11e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019ef026-b569-778e-95c5-5d5f4c590806" xlink:to="loc_us-gaap_EarningsPerShareBasic_019ef026-b569-78d7-a945-f9d088c1d11e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019ef026-b569-7e9b-906f-862902b1fd7b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareBasicAbstract_019ef026-b569-778e-95c5-5d5f4c590806" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019ef026-b569-7e9b-906f-862902b1fd7b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019ef026-b569-7604-9452-0faf5d866a6b" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019fcd47-b0e6-761f-bda0-f126ec62d589" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount_019ef026-b569-7604-9452-0faf5d866a6b" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/SEGMENTINFORMATIONScheduleofReconciliationofEarningsFromOperationsDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#SEGMENTINFORMATIONScheduleofReconciliationofEarningsFromOperationsDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/SEGMENTINFORMATIONScheduleofReconciliationofEarningsFromOperationsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef026-b569-7908-a306-173e758f1dbf" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef026-b569-7908-a306-173e758f1dbf" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019ef026-b569-7bc4-9dde-fa131e7192fe" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef026-b569-7908-a306-173e758f1dbf" xlink:to="loc_srt_ConsolidationItemsAxis_019ef026-b569-7bc4-9dde-fa131e7192fe" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019ef026-b569-7bc4-9dde-fa131e7192fe_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019ef026-b569-7bc4-9dde-fa131e7192fe" xlink:to="loc_srt_ConsolidationItemsDomain_019ef026-b569-7bc4-9dde-fa131e7192fe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019ef026-b569-701d-83a4-1d5bee681ea6" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019ef026-b569-7bc4-9dde-fa131e7192fe" xlink:to="loc_srt_ConsolidationItemsDomain_019ef026-b569-701d-83a4-1d5bee681ea6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019ef026-b569-7b0b-8fc6-839a4c1065e7" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019ef026-b569-701d-83a4-1d5bee681ea6" xlink:to="loc_us-gaap_OperatingSegmentsMember_019ef026-b569-7b0b-8fc6-839a4c1065e7" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntersegmentEliminationMember_019ef026-b569-7fb5-ba5b-44a2669394cd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IntersegmentEliminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019ef026-b569-701d-83a4-1d5bee681ea6" xlink:to="loc_us-gaap_IntersegmentEliminationMember_019ef026-b569-7fb5-ba5b-44a2669394cd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019ef026-b569-7fb5-8156-7a405da42480" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef026-b569-7908-a306-173e758f1dbf" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019ef026-b569-7fb5-8156-7a405da42480" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019ef026-b569-7fb5-8156-7a405da42480_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019ef026-b569-7fb5-8156-7a405da42480" xlink:to="loc_us-gaap_SegmentDomain_019ef026-b569-7fb5-8156-7a405da42480_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019ef026-b569-7df2-8d20-74d44f5bffbd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019ef026-b569-7fb5-8156-7a405da42480" xlink:to="loc_us-gaap_SegmentDomain_019ef026-b569-7df2-8d20-74d44f5bffbd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_CoreNutritionalMember_019ef026-b569-78be-b299-e47912374e34" xlink:href="usna-20260704.xsd#usna_CoreNutritionalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019ef026-b569-7df2-8d20-74d44f5bffbd" xlink:to="loc_usna_CoreNutritionalMember_019ef026-b569-78be-b299-e47912374e34" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_HiyaMember_019ef026-b569-77ca-878e-f375c6882581" xlink:href="usna-20260704.xsd#usna_HiyaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019ef026-b569-7df2-8d20-74d44f5bffbd" xlink:to="loc_usna_HiyaMember_019ef026-b569-77ca-878e-f375c6882581" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_RiseMember_019ef026-b569-7694-b28f-ca1a3bbd89a2" xlink:href="usna-20260704.xsd#usna_RiseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019ef026-b569-7df2-8d20-74d44f5bffbd" xlink:to="loc_usna_RiseMember_019ef026-b569-7694-b28f-ca1a3bbd89a2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019ef026-b569-7a11-8b90-24230b404b16" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019ef026-b569-7a11-8b90-24230b404b16" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019ef026-b569-73d3-b9f7-2b35902a5ccd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019ef026-b569-73d3-b9f7-2b35902a5ccd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_BrandPartnerIncentives_019ef026-b569-7cf1-86fc-1b91dd386072" xlink:href="usna-20260704.xsd#usna_BrandPartnerIncentives"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:to="loc_usna_BrandPartnerIncentives_019ef026-b569-7cf1-86fc-1b91dd386072" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019ef026-b569-77f7-bb09-acba5585fb2f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019ef026-b569-77f7-bb09-acba5585fb2f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillImpairmentLoss_019fc5eb-e0cc-7594-8753-5719b45f0192" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_GoodwillImpairmentLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:to="loc_us-gaap_GoodwillImpairmentLoss_019fc5eb-e0cc-7594-8753-5719b45f0192" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019ef026-b569-76aa-8b7f-af7fa1cac8b8" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:to="loc_us-gaap_OperatingIncomeLoss_019ef026-b569-76aa-8b7f-af7fa1cac8b8" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InvestmentIncomeInterest_019ef026-b569-75d4-9a5e-1344cabf4470" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InvestmentIncomeInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:to="loc_us-gaap_InvestmentIncomeInterest_019ef026-b569-75d4-9a5e-1344cabf4470" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpenseNonoperating_019ef026-b569-705b-8a41-00a3eecf3063" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_InterestExpenseNonoperating"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:to="loc_us-gaap_InterestExpenseNonoperating_019ef026-b569-705b-8a41-00a3eecf3063" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherNonoperatingIncomeExpense_019ef026-b569-7efe-816f-b770e1b81d1e" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_OtherNonoperatingIncomeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:to="loc_us-gaap_OtherNonoperatingIncomeExpense_019ef026-b569-7efe-816f-b770e1b81d1e" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019ef026-b569-77be-bc14-6ed7af8a2ede" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019ef026-b569-77be-bc14-6ed7af8a2ede" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019ef026-b569-761a-9020-74c844003932" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d21-bc9d-e55c7b5a413c" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019ef026-b569-761a-9020-74c844003932" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/SEGMENTINFORMATIONScheduleofSegmentReportingInformationbyOperatingSegmentDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#SEGMENTINFORMATIONScheduleofSegmentReportingInformationbyOperatingSegmentDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/SEGMENTINFORMATIONScheduleofSegmentReportingInformationbyOperatingSegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-75a2-9eb3-74f79b5c40e6" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef026-b569-7bb2-8722-d796b789f29c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-75a2-9eb3-74f79b5c40e6" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef026-b569-7bb2-8722-d796b789f29c" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019ef026-b569-7557-bc9b-db972964264f" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef026-b569-7bb2-8722-d796b789f29c" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019ef026-b569-7557-bc9b-db972964264f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019ef026-b569-7557-bc9b-db972964264f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019ef026-b569-7557-bc9b-db972964264f" xlink:to="loc_us-gaap_SegmentDomain_019ef026-b569-7557-bc9b-db972964264f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019ef026-b569-73f5-9edf-975a0b2bd2c5" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019ef026-b569-7557-bc9b-db972964264f" xlink:to="loc_us-gaap_SegmentDomain_019ef026-b569-73f5-9edf-975a0b2bd2c5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_CoreNutritionalMember_019ef026-b569-7f54-ad1a-b11d96e6ae20" xlink:href="usna-20260704.xsd#usna_CoreNutritionalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019ef026-b569-73f5-9edf-975a0b2bd2c5" xlink:to="loc_usna_CoreNutritionalMember_019ef026-b569-7f54-ad1a-b11d96e6ae20" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_HiyaMember_019ef026-b569-71ae-9320-ad399a7e6b0c" xlink:href="usna-20260704.xsd#usna_HiyaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019ef026-b569-73f5-9edf-975a0b2bd2c5" xlink:to="loc_usna_HiyaMember_019ef026-b569-71ae-9320-ad399a7e6b0c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_RiseMember_019ef026-b569-7998-9368-f69b7254f08a" xlink:href="usna-20260704.xsd#usna_RiseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019ef026-b569-73f5-9edf-975a0b2bd2c5" xlink:to="loc_usna_RiseMember_019ef026-b569-7998-9368-f69b7254f08a" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_019ef026-b569-74b1-9c28-090e58e36fa1" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-75a2-9eb3-74f79b5c40e6" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_019ef026-b569-74b1-9c28-090e58e36fa1" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/SEGMENTINFORMATIONScheduleofRevenuePercentageByProductDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#SEGMENTINFORMATIONScheduleofRevenuePercentageByProductDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/SEGMENTINFORMATIONScheduleofRevenuePercentageByProductDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d1d-8ee6-2b15cb617044" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SegmentReportingInformationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef026-b569-7c76-82f3-c6aedb5c0cfd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d1d-8ee6-2b15cb617044" xlink:to="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef026-b569-7c76-82f3-c6aedb5c0cfd" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019ef026-b569-73fd-a8f8-81d1b0d0af12" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef026-b569-7c76-82f3-c6aedb5c0cfd" xlink:to="loc_srt_ProductOrServiceAxis_019ef026-b569-73fd-a8f8-81d1b0d0af12" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019ef026-b569-73fd-a8f8-81d1b0d0af12_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019ef026-b569-73fd-a8f8-81d1b0d0af12" xlink:to="loc_srt_ProductsAndServicesDomain_019ef026-b569-73fd-a8f8-81d1b0d0af12_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019ef026-b569-7efc-a0d4-6666ee2896a9" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019ef026-b569-73fd-a8f8-81d1b0d0af12" xlink:to="loc_srt_ProductsAndServicesDomain_019ef026-b569-7efc-a0d4-6666ee2896a9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_USANANutritionalsMember_019ef026-b569-7df9-bbd9-a676e95f5b42" xlink:href="usna-20260704.xsd#usna_USANANutritionalsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef026-b569-7efc-a0d4-6666ee2896a9" xlink:to="loc_usna_USANANutritionalsMember_019ef026-b569-7df9-bbd9-a676e95f5b42" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_USANAFoodsMember_019ef026-b569-76c2-bd0a-f8a9a0d9e27e" xlink:href="usna-20260704.xsd#usna_USANAFoodsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef026-b569-7efc-a0d4-6666ee2896a9" xlink:to="loc_usna_USANAFoodsMember_019ef026-b569-76c2-bd0a-f8a9a0d9e27e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_PersonalCareAndSkincareMember_019ef026-b569-73ac-9cad-c140b818628b" xlink:href="usna-20260704.xsd#usna_PersonalCareAndSkincareMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef026-b569-7efc-a0d4-6666ee2896a9" xlink:to="loc_usna_PersonalCareAndSkincareMember_019ef026-b569-73ac-9cad-c140b818628b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_HiyaMember_019ef026-b569-7959-aeb2-dbce49530d54" xlink:href="usna-20260704.xsd#usna_HiyaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef026-b569-7efc-a0d4-6666ee2896a9" xlink:to="loc_usna_HiyaMember_019ef026-b569-7959-aeb2-dbce49530d54" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_RiseMember_019ef026-b569-79ee-866e-1ccea8ac3123" xlink:href="usna-20260704.xsd#usna_RiseMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019ef026-b569-7efc-a0d4-6666ee2896a9" xlink:to="loc_usna_RiseMember_019ef026-b569-79ee-866e-1ccea8ac3123" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByTypeAxis_019ef026-b569-7c73-9200-6ab680661be4" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef026-b569-7c76-82f3-c6aedb5c0cfd" xlink:to="loc_us-gaap_ConcentrationRiskByTypeAxis_019ef026-b569-7c73-9200-6ab680661be4" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019ef026-b569-7c73-9200-6ab680661be4_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019ef026-b569-7c73-9200-6ab680661be4" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019ef026-b569-7c73-9200-6ab680661be4_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskTypeDomain_019ef026-b569-7bd2-b9cc-a9e648973163" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByTypeAxis_019ef026-b569-7c73-9200-6ab680661be4" xlink:to="loc_us-gaap_ConcentrationRiskTypeDomain_019ef026-b569-7bd2-b9cc-a9e648973163" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductConcentrationRiskMember_019ef026-b569-79f3-9d0c-82c273d44f8c" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ProductConcentrationRiskMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskTypeDomain_019ef026-b569-7bd2-b9cc-a9e648973163" xlink:to="loc_us-gaap_ProductConcentrationRiskMember_019ef026-b569-79f3-9d0c-82c273d44f8c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019ef026-b569-73e2-b299-b8c97ac566fe" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskByBenchmarkAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfSegmentReportingInformationBySegmentTable_019ef026-b569-7c76-82f3-c6aedb5c0cfd" xlink:to="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019ef026-b569-73e2-b299-b8c97ac566fe" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef026-b569-73e2-b299-b8c97ac566fe_default" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019ef026-b569-73e2-b299-b8c97ac566fe" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef026-b569-73e2-b299-b8c97ac566fe_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef026-b569-70f7-ac16-7ecbb51468fd" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskBenchmarkDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_ConcentrationRiskByBenchmarkAxis_019ef026-b569-73e2-b299-b8c97ac566fe" xlink:to="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef026-b569-70f7-ac16-7ecbb51468fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SalesRevenueNetMember_019ef026-b569-72f6-81ed-cb27912f7742" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_SalesRevenueNetMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_ConcentrationRiskBenchmarkDomain_019ef026-b569-70f7-ac16-7ecbb51468fd" xlink:to="loc_us-gaap_SalesRevenueNetMember_019ef026-b569-72f6-81ed-cb27912f7742" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConcentrationRiskPercentage1_019ef026-b569-7c7b-a655-2a8e5faa0ab3" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ConcentrationRiskPercentage1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingInformationLineItems_019ef026-b569-7d1d-8ee6-2b15cb617044" xlink:to="loc_us-gaap_ConcentrationRiskPercentage1_019ef026-b569-7c7b-a655-2a8e5faa0ab3" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/SEGMENTINFORMATIONScheduleofConsolidatedNetSalesandLongLivedAssetsDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#SEGMENTINFORMATIONScheduleofConsolidatedNetSalesandLongLivedAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/SEGMENTINFORMATIONScheduleofConsolidatedNetSalesandLongLivedAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019ef026-b569-7aad-9f5b-92f118854679" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019ef026-b569-7a19-890c-844e7603f0fa" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019ef026-b569-7aad-9f5b-92f118854679" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019ef026-b569-7a19-890c-844e7603f0fa" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019ef026-b569-7d5c-a9af-a34a3ce016c3" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019ef026-b569-7a19-890c-844e7603f0fa" xlink:to="loc_srt_StatementGeographicalAxis_019ef026-b569-7d5c-a9af-a34a3ce016c3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019ef026-b569-7d5c-a9af-a34a3ce016c3_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019ef026-b569-7d5c-a9af-a34a3ce016c3" xlink:to="loc_srt_SegmentGeographicalDomain_019ef026-b569-7d5c-a9af-a34a3ce016c3_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019ef026-b569-7cb8-8673-72ff4a0b3200" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019ef026-b569-7d5c-a9af-a34a3ce016c3" xlink:to="loc_srt_SegmentGeographicalDomain_019ef026-b569-7cb8-8673-72ff4a0b3200" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_AsiaPacificMember_019ef026-b569-79b9-948f-04cbaff5e9af" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_AsiaPacificMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019ef026-b569-7cb8-8673-72ff4a0b3200" xlink:to="loc_srt_AsiaPacificMember_019ef026-b569-79b9-948f-04cbaff5e9af" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_GreaterChinaMember_019ef026-b569-7709-9741-a4c79e38ac7d" xlink:href="usna-20260704.xsd#usna_GreaterChinaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_AsiaPacificMember_019ef026-b569-79b9-948f-04cbaff5e9af" xlink:to="loc_usna_GreaterChinaMember_019ef026-b569-7709-9741-a4c79e38ac7d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_SoutheastAsiaPacificMember_019ef026-b569-784f-9c84-684c96e254bb" xlink:href="usna-20260704.xsd#usna_SoutheastAsiaPacificMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_AsiaPacificMember_019ef026-b569-79b9-948f-04cbaff5e9af" xlink:to="loc_usna_SoutheastAsiaPacificMember_019ef026-b569-784f-9c84-684c96e254bb" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_NorthAsiaMember_019ef026-b569-7f83-9f52-3779ce49a813" xlink:href="usna-20260704.xsd#usna_NorthAsiaMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_AsiaPacificMember_019ef026-b569-79b9-948f-04cbaff5e9af" xlink:to="loc_usna_NorthAsiaMember_019ef026-b569-7f83-9f52-3779ce49a813" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_usna_AmericasAndEuropeMember_019ef026-b569-77ef-beab-2c20c6112524" xlink:href="usna-20260704.xsd#usna_AmericasAndEuropeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019ef026-b569-7cb8-8673-72ff4a0b3200" xlink:to="loc_usna_AmericasAndEuropeMember_019ef026-b569-77ef-beab-2c20c6112524" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019ef026-b569-72a0-98d7-46d0f9e359e9" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019ef026-b569-7aad-9f5b-92f118854679" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019ef026-b569-72a0-98d7-46d0f9e359e9" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.usana.com/role/SEGMENTINFORMATIONScheduleofMarketsRepresentingTenPercentOrMoreOfConsolidatedNetSalesandLongLivedAssetsDetails" xlink:type="simple" xlink:href="usna-20260704.xsd#SEGMENTINFORMATIONScheduleofMarketsRepresentingTenPercentOrMoreOfConsolidatedNetSalesandLongLivedAssetsDetails"/>
  <link:definitionLink xlink:role="http://www.usana.com/role/SEGMENTINFORMATIONScheduleofMarketsRepresentingTenPercentOrMoreOfConsolidatedNetSalesandLongLivedAssetsDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019ef026-b569-7612-baf0-be37d9ca34eb" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019ef026-b569-7e1d-bbc1-1788bd4e6277" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019ef026-b569-7612-baf0-be37d9ca34eb" xlink:to="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019ef026-b569-7e1d-bbc1-1788bd4e6277" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019ef026-b569-798c-8c12-f4278f6b3e58" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRevenuesFromExternalCustomersAndLongLivedAssetsTable_019ef026-b569-7e1d-bbc1-1788bd4e6277" xlink:to="loc_srt_StatementGeographicalAxis_019ef026-b569-798c-8c12-f4278f6b3e58" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019ef026-b569-798c-8c12-f4278f6b3e58_default" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019ef026-b569-798c-8c12-f4278f6b3e58" xlink:to="loc_srt_SegmentGeographicalDomain_019ef026-b569-798c-8c12-f4278f6b3e58_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019ef026-b569-70be-9838-a07925a05158" xlink:href="https://xbrl.fasb.org/srt/2026/elts/srt-2026.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019ef026-b569-798c-8c12-f4278f6b3e58" xlink:to="loc_srt_SegmentGeographicalDomain_019ef026-b569-70be-9838-a07925a05158" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_CN_019ef026-b569-725d-abff-e589049be7ac" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_CN"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019ef026-b569-70be-9838-a07925a05158" xlink:to="loc_country_CN_019ef026-b569-725d-abff-e589049be7ac" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019ef026-b569-7eca-9ec0-97c203e2e517" xlink:href="https://xbrl.sec.gov/country/2026/country-2026.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019ef026-b569-70be-9838-a07925a05158" xlink:to="loc_country_US_019ef026-b569-7eca-9ec0-97c203e2e517" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019ef026-b569-7864-a241-a03b3bbf7299" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019ef026-b569-7612-baf0-be37d9ca34eb" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019ef026-b569-7864-a241-a03b3bbf7299" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NoncurrentAssets_019ef026-b569-7af1-8d57-6a8d2d5b469a" xlink:href="https://xbrl.fasb.org/us-gaap/2026/elts/us-gaap-2026.xsd#us-gaap_NoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems_019ef026-b569-7612-baf0-be37d9ca34eb" xlink:to="loc_us-gaap_NoncurrentAssets_019ef026-b569-7af1-8d57-6a8d2d5b469a" xlink:type="arc" order="1"/>
  </link:definitionLink>
</link:linkbase>
