Retatrutide

Retatrutide (LY3437943) is an investigational, once-weekly injectable peptide developed by Eli Lilly. It is a first-in-class "triple agonist" that simultaneously activates the GIP, GLP-1, and glucagon receptors. The glucagon-receptor component is the main feature distinguishing it from dual agonists like tirzepatide, and is thought to add an energy-expenditure effect on top of appetite suppression. In a 48-week phase 2 obesity trial (NEJM, 2023), the highest 12 mg dose produced a mean weight reduction of about 24.2%, among the largest reductions reported for any pharmacologic obesity agent in trials to date. A separate phase 2a trial showed marked reductions in liver fat in people with metabolic dysfunction-associated steatotic liver disease (MASLD). Eli Lilly's phase 3 TRIUMPH program is ongoing. As of mid-2026, retatrutide is NOT approved by the FDA, EMA, or any major regulator and remains an experimental compound under clinical investigation. Material sold by research-chemical vendors is unregulated, not pharmaceutical-grade, and is labeled research-use-only. The data below summarizes published evidence and clearly separates clinical findings from anecdotal community use.