v3.26.1
Document and Entity Information - shares
 3 Months Ended
Mar. 31, 2026
May 01, 2026
Cover [Abstract]    
Document Type 10-Q  
Amendment Flag false  
Document Quarterly Report true  
Document Period End Date Mar. 31, 2026  
Document Fiscal Year Focus 2026  
Document Fiscal Period Focus Q1  
Document Transition Report false  
Current Fiscal Year End Date --12-31  
Entity File Number 001-41942  
Entity Registrant Name Fractyl Health, Inc.  
Entity Central Index Key 0001572616  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 27-3553477  
Entity Address, Address Line One 3 Van de Graaff Drive  
Entity Address, Address Line Two Suite 200  
Entity Address, City or Town Burlington  
Entity Address, State or Province MA  
Entity Address, Postal Zip Code 01803  
City Area Code 781  
Local Phone Number 902-8800  
Title of 12(b) Security Common Stock, $0.00001 par value per share  
Trading Symbol GUTS  
Security Exchange Name NASDAQ  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business true  
Entity Emerging Growth Company true  
Entity Ex Transition Period false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   158,648,963