- On 21 July 2026, Lilly reported TRIUMPH-1 topline results: 28.3% mean weight loss at 80 weeks on 12 mg in adults with obesity/overweight without diabetes.
- Lower doses still worked: 25.9% (9 mg) and 19.0% (4 mg), vs. ~2.2% placebo. A higher-BMI extension reached ~30.3% at 104 weeks.
- It's a bigger number than semaglutide's and tirzepatide's registrational trials — but those were separate studies, not head-to-head.
- Retatrutide is investigational and not FDA-approved. The trial showed weight and risk-marker changes, not proven reductions in heart attacks, stroke, cancer, or death.
What TRIUMPH-1 measured
TRIUMPH-1 is the pivotal general-obesity trial in Lilly's broader TRIUMPH Phase 3 program. It randomized 2,339 adults with obesity or overweight and at least one weight-related condition (but not diabetes) to once-weekly retatrutide 4 mg, 9 mg, 12 mg, or placebo, titrating up from 2 mg. The primary endpoint was percent change in body weight at 80 weeks.
TRIUMPH-1 — mean weight loss by dose
Lilly also reported that roughly 45% of participants on 12 mg achieved at least 30% weight loss — a threshold that begins to approach what bariatric surgery achieves, which is why the result drew so much attention.
How it compares to what's already approved
The headline number is larger than the registrational figures for the two leading approved options. But this is the most over-claimed part of the GLP-1 conversation, so be precise: these come from different trials, with different durations, doses, and patient populations. They are not a head-to-head comparison.
Registrational weight-loss figures — different trials
| Molecule | Class | Trial & dose | Mean loss | Status |
|---|---|---|---|---|
| Semaglutide | GLP-1 | STEP-1, 2.4 mg | 14.9% | FDA-approved |
| Tirzepatide | GIP/GLP-1 | SURMOUNT-1, 15 mg | 22.5% | FDA-approved |
| Retatrutide | GIP/GLP-1/glucagon | TRIUMPH-1, 12 mg | 28.3% | Investigational |
Why a "triple agonist" might do more
Semaglutide targets one receptor (GLP-1). Tirzepatide targets two (GIP and GLP-1). Retatrutide adds a third — glucagon — which is thought to increase energy expenditure on top of the appetite and satiety effects of the other two. More targets is the leading hypothesis for the larger figure, though the trial measured outcomes, not mechanism.
What TRIUMPH-1 did not show
As with the whole class, weight tends to return after stopping treatment: discontinuation studies of semaglutide and tirzepatide showed participants regaining roughly two-thirds of lost weight within about a year. There is no reason yet to assume retatrutide is different. These are tools for ongoing management, not one-time cures.
Can you get retatrutide now?
FAQ
How much weight did people lose on retatrutide?
Is retatrutide better than Ozempic, Wegovy, Mounjaro, or Zepbound?
When could it be approved?
Sources
- Eli Lilly — TRIUMPH-1 topline Phase 3 results (21 July 2026).
- The Pharmaceutical Journal; Pharmacy Times — TRIUMPH-1 coverage (July 2026).
- STEP-1 (Wilding et al., NEJM 2021) — semaglutide 2.4 mg, 14.9%.
- SURMOUNT-1 (Jastreboff et al., NEJM 2022) — tirzepatide 15 mg, 22.5%.
- SURMOUNT-5 (Aronne et al., NEJM 2025) — head-to-head, tirzepatide 20.2% vs semaglutide 13.7%.