Results & Outcomes
Every published and registered retatrutide trial result, organized by phase. Evidence ratings reflect study design quality. TRIUMPH-1 Phase 3 topline results announced May 21, 2026.
Short answer: In the landmark Phase 2 trial, retatrutide produced a mean weight loss of 24.2% at 48 weeks at the 12 mg dose. TRIUMPH-1 Phase 3 topline results (May 21, 2026) showed 28.3% mean body weight reduction at 80 weeks (12 mg), 25.9% at 9 mg, and 19.0% at 4 mg. Peer-reviewed publication is pending. The only legal way to access retatrutide today is through an authorized clinical trial.
Key Facts
Phase 1
Single Ascending Dose (SAD)
Established safety, tolerability, PK/PD profile. Enabled Phase 2 dose selection.
Eli Lilly IND filing ↗Multiple Ascending Dose (MAD)
Confirmed dose-dependent weight reduction. Informed Phase 2 dose range.
Eli Lilly IND filing ↗Phase 2
Jastreboff et al. 2023 (NEJM)
Landmark Phase 2 RCT. Highest weight loss reported for any pharmacological agent in a published trial at time of publication. Dose-dependent response across 1 mg, 4 mg, 8 mg, 12 mg arms.
New England Journal of Medicine, 2023 ↗Retatrutide in Type 2 Diabetes
Significant HbA1c reductions alongside weight loss. Demonstrated dual metabolic benefit in T2D population.
The Lancet, 2023 ↗Phase 3
TRIUMPH-1 (Obesity)
Phase 3 topline results reported by Eli Lilly. Mean body-weight reductions at Week 80: 4 mg −19.0%, 9 mg −25.9%, 12 mg −28.3%. These are Phase 3 topline findings and should not be confused with the earlier 48-week Phase 2 obesity trial (24.2% at 48 weeks). The 30.3% figure is from a prespecified extension population with baseline BMI ≥35 at 104 weeks. Retatrutide remains investigational and is not FDA approved. Peer-reviewed publication pending.
Eli Lilly Investor Relations — May 21, 2026 topline announcement ↗TRIUMPH-2 (T2D + Obesity)
Topline Phase 3 results announced July 23, 2026. Efficacy-estimand mean body-weight changes at 80 weeks: 4 mg −12.7%, 9 mg −19.1%, 12 mg −20.8% vs. placebo −4.0%. A1C reductions averaged 1.6 percentage points. Peer-reviewed publication pending.
Eli Lilly Investor Relations — July 23, 2026 topline announcement ↗TRIUMPH-3 (Cardiovascular Disease + Severe Obesity)
Topline Phase 3 results announced July 23, 2026. Reported mean weight loss reached 22.6% at the highest studied dose at 80 weeks. Population included adults with severe obesity and established cardiovascular disease, with or without T2D. Topline data do not establish a demonstrated cardiovascular-outcome benefit; long-term cardiovascular outcomes follow-up continues. Peer-reviewed publication pending.
Eli Lilly Investor Relations — July 23, 2026 topline announcement ↗Why Does Retatrutide Produce Greater Weight Loss?
Retatrutide is a triple-receptor agonist that simultaneously activates GIP, GLP-1, and glucagon receptors. The addition of glucagon receptor agonism — absent in semaglutide (GLP-1 only) and tirzepatide (GIP/GLP-1) — increases hepatic glucose output and resting energy expenditure. This means the body burns more calories at rest, compounding the appetite suppression provided by GLP-1 and GIP agonism.
For a full mechanistic explanation, see How Retatrutide Works. For a direct comparison with the next generation of obesity drugs in development, see Retatrutide vs. Next-Generation Obesity Drugs.
Frequently Asked Questions
How much weight loss has been shown in retatrutide trials?
In the Phase 2 trial published in the New England Journal of Medicine (Jastreboff et al., 2023), participants receiving 12 mg retatrutide lost a mean of 24.2% of body weight at 48 weeks vs. 2.1% on placebo. In the TRIUMPH-1 Phase 3 trial, Eli Lilly announced topline results on May 21, 2026: 28.3% mean body weight reduction at 80 weeks (12 mg), 25.9% (9 mg), and 19.0% (4 mg). A prespecified extension population with baseline BMI ≥35 showed up to 30.3% at 104 weeks. These are topline results; peer-reviewed publication is pending.
How does retatrutide compare to semaglutide and tirzepatide on weight loss?
Cross-trial comparisons (not head-to-head) suggest retatrutide's Phase 3 result of 28.3% at 80 weeks exceeds semaglutide's ~15% at 68 weeks (STEP 1) and tirzepatide's ~22.5% at 72 weeks (SURMOUNT-1). These are not directly comparable due to different populations, durations, and designs. No head-to-head trial has been published. See our dedicated comparison pages for full analysis.
What were the results in people with type 2 diabetes?
In the Phase 2 T2D trial (The Lancet, 2023), participants receiving 12 mg retatrutide lost approximately 16.9% of body weight at 36 weeks, with significant HbA1c reductions alongside weight loss. In the TRIUMPH-2 Phase 3 trial (topline results July 23, 2026), participants with obesity or overweight and type 2 diabetes lost up to an average of 20.8% body weight at 80 weeks. Peer-reviewed publication of TRIUMPH-2 is pending.
What is the TRIUMPH trial program?
TRIUMPH is Eli Lilly's Phase 3 clinical program for retatrutide. Eli Lilly has reported five positive Phase 3 retatrutide studies. TRIUMPH-1 (obesity, approximately 2,339 randomized participants per Lilly reporting; ClinicalTrials.gov actual enrollment: 2,335; 80 weeks) reported topline results on May 21, 2026: 28.3% mean weight loss at 80 weeks (12 mg). TRIUMPH-2 (T2D + obesity) reported topline results on July 23, 2026: up to 20.8% weight loss at 80 weeks. TRIUMPH-3 (severe obesity + cardiovascular disease) reported topline results on July 23, 2026: up to 22.6% weight loss at 80 weeks. Peer-reviewed publications are pending for all three. Lilly states it now has the clinical data package needed to support global submissions for obesity, knee osteoarthritis pain, and obstructive sleep apnea.
Why is retatrutide's weight loss higher than other GLP-1 drugs?
Retatrutide is a triple-receptor agonist that activates GIP, GLP-1, and glucagon receptors simultaneously. The addition of glucagon receptor agonism increases energy expenditure — the body burns more calories at rest — on top of the appetite suppression provided by GLP-1 and GIP agonism. This triple mechanism is the leading explanation for the greater weight loss observed. See our How It Works page for a full mechanistic explanation.
When will Phase 3 results be available?
TRIUMPH-1 topline results were announced by Eli Lilly on May 21, 2026. TRIUMPH-2 and TRIUMPH-3 topline results were announced on July 23, 2026. Eli Lilly reports five positive Phase 3 retatrutide studies and states it now has the clinical data package needed to support global submissions for obesity, knee osteoarthritis pain, and obstructive sleep apnea. Lilly plans to submit a regulatory application to the FDA in Q1 2027. Peer-reviewed publications of the full datasets are pending. Approval and commercial availability are not guaranteed.
Are these results from real clinical trials or anecdotal reports?
All results on this page are from registered clinical trials published in peer-reviewed journals (NEJM, The Lancet) or registered on ClinicalTrials.gov. Phase 1 and 2 data are from completed, peer-reviewed trials. TRIUMPH-1 Phase 3 topline data are from Eli Lilly's May 21, 2026 announcement; peer-reviewed publication is pending. For anecdotal community reports, see the Reddit Observatory.