Weight & metabolism
Retatrutide
LY3437943, triple agonist
Retatrutide is an investigational Eli Lilly drug that activates GIP, GLP-1 and glucagon receptors at once. It has produced large weight loss in phase 3 trials but is not FDA-approved.
Key facts
- Commonly discussed for: weight loss beyond current GLP-1 drugs.
- Evidence (B): The phase 3 TRIUMPH-1 trial (2,339 adults, 80 weeks, published in NEJM in September 2026) reported 25.0% average weight loss at the highest dose versus 3.9% with placebo (intention-to-treat; Lilly's topline efficacy figure was 28.3%). Graded B because it is not yet approved.
- FDA status: In FDA trials. As of October 2026 retatrutide is not FDA-approved; Lilly said in July 2026 it plans to submit for FDA approval in the first quarter of 2027, and it runs a narrow compassionate-use program.
- Legitimate access: Clinical trial only.
- Last reviewed: October 1, 2026.
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- Jastreboff et al. Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity (TRIUMPH-1). N Engl J Med, 2026
- BioPharma Dive: Lilly, with new data, to seek FDA approval of obesity drug retatrutide (July 2026)
- TCTMD: Retatrutide achieves large weight decreases in patients without diabetes (TRIUMPH-1)
- AJMC: Lilly expands retatrutide access amid doctor pushback (August 2026)