Weight-loss drug trial data
Published trial results for nine GLP-1 and incretin compounds — each with its trial, duration, population and primary citation, and an explicit note on which figures we have checked against the source.
Of published trial results, retatrutide reports the largest mean weight loss at −24.2% over 48 weeks (12 mg, Phase 2), followed by tirzepatide at −20.9% over 72 weeks and CagriSema at −20.4% over 68 weeks. Only tirzepatide and semaglutide are FDA-approved for weight management; the rest remain investigational. These come from separate trials of differing length and population and are therefore not directly comparable — the one head-to-head trial, SURMOUNT-5, put tirzepatide at −20.2% against semaglutide at −13.7% over 72 weeks.
The short version.
- Retatrutide holds the largest published weight-loss result of any incretin drug: −24.2% over 48 weeks, but only in a Phase 2 trial.
- Only two of the nine compounds are FDA-approved for weight management: semaglutide and tirzepatide.
- The only head-to-head trial, SURMOUNT-5, put tirzepatide at −20.2% and semaglutide at −13.7% over 72 weeks.
- Semaglutide’s STEP 1 result is −14.9%, not the 15.2% widely quoted.
- Six of the nine figures in common circulation for these compounds are wrong, overstated, or attributed to the wrong trial.
Every compound, with its source.
Percentages are the published primary endpoint for the arm named. They are not press-release figures, completer analyses or subgroup results — which is where most of the inflated numbers in circulation originate.
| Compound | Weight loss | Placebo | Duration | Trial | Status | Source |
|---|---|---|---|---|---|---|
| Retatrutide (12 mg)Phase 2, not Phase 3. Lower arms: 8 mg −22.8%, 4 mg −17.1%, 1 mg −8.7%. | −24.2% | −2.1% | 48 weeks | Phase 2 | Investigational — Phase 3 ongoing | VerifiedJastreboff AM et al. N Engl J Med 2023;389:514–526 |
| Tirzepatide (15 mg)Lower arms: 10 mg −19.5%, 5 mg −15.0%. | −20.9% | — | 72 weeks | SURMOUNT-1 | FDA approved (Zepbound) | VerifiedJastreboff AM et al. N Engl J Med 2022;387:205–216 |
| CagriSema (2.4/2.4 mg)REDEFINE 2, in type 2 diabetes, reported −13.7%. The two are frequently confused. | −20.4% | −3.0% | 68 weeks | REDEFINE 1 | Investigational — Phase 3 | VerifiedGarvey WT et al. N Engl J Med 2025;393:635–647 |
| Pemvidutide (2.4 mg)20% of participants discontinued the 2.4 mg dose for adverse events. | −15.6% | — | 48 weeks | MOMENTUM (Phase 2) | Investigational — Phase 2 | VerifiedMOMENTUM Phase 2, 48-week results |
| Survodutide (4.8 mg)Lower arms: 3.6 mg −13.2%, 2.4 mg −12.5%, 0.6 mg −6.2%. | −14.9% | −2.8% | 46 weeks | Phase 2 dose-finding | Investigational — Phase 3 ongoing | Verifiedle Roux CW et al. Lancet Diabetes Endocrinol 2024 |
| Mazdutide (6 mg)4 mg arm −11.0%. Trial maximum was 6 mg. Chinese population only. | −14.0% | +0.3% | 48 weeks | GLORY-1 | Investigational — Phase 3 | VerifiedOnce-Weekly Mazdutide in Chinese Adults. N Engl J Med 2025 |
| Orforglipron (36 mg)Lower arms: 12 mg −8.4%, 6 mg −7.5%. Widely quoted at 14.7%, which is the Phase 2 figure. | −11.2% | — | 72 weeks | ATTAIN-1 | Investigational — Phase 3. Oral, once daily. | VerifiedATTAIN-1 Phase 3, 72-week results |
| Semaglutide (2.4 mg)Widely misquoted as 15.2%. Treatment difference vs placebo: 12.4 points. | −14.9% | −2.4% | 68 weeks | STEP 1 | FDA approved (Wegovy) | VerifiedWilding JPH et al. N Engl J Med 2021;384:989–1002 |
| CagrilintideOur source labels this REDEFINE 1, which is the CagriSema combination trial. Likely a different study. | −10.8% | — | Not stated in our source | Trial label uncertain | Investigational — Phase 3 | Unverified |
“Unverified” means we have not yet traced that figure to its primary publication. It is not a claim the number is wrong — it is a statement that we have not checked it, and you should not cite it from us until we have.
The only direct comparison.
Every figure in the table above comes from a trial of one drug against placebo. Ranking them against each other is informative but not rigorous: the trials differ in length, enrolment criteria and population.
One trial tested two of these compounds against each other directly. SURMOUNT-5 randomised participants to tirzepatide or semaglutide at maximum tolerated doses for 72 weeks: tirzepatide −20.2%, semaglutide −13.7%.
Aronne LJ, Horn DB, le Roux CW, et al. N Engl J Med 2025;393:26–36 · Full comparison →
What we got wrong.
Compiling this page found three errors in our own dataset. They are listed rather than quietly fixed — a page asking to be treated as a reference should show its working.
- Semaglutide / STEP 1 was recorded as 15.2%. The published primary endpoint is −14.9%.
- CagriSema was recorded as 25.3% and attributed to REDEFINE 2. REDEFINE 1 (obesity) reported −20.4%; REDEFINE 2 (type 2 diabetes) reported −13.7%. Neither is 25.3%. Correcting it changed the ranking — CagriSema is not the leader.
- Retatrutide’s 24.2% was labelled “TRIUMPH-2”. The figure is right but it is the Phase 2 obesity trial; TRIUMPH is the Phase 3 programme.
- Survodutide was recorded as 19% from a trial called “ACHIEVE”. The Phase 2 dose-finding trial reported −14.9% at 4.8 mg, and ACHIEVE is not the survodutide programme.
- Mazdutide was recorded as 18.6% with a 9 mg maximum. GLORY-1 tested 4 mg and 6 mg, reporting −11.0% and −14.0%.
- Orforglipron was recorded as 14.7%, which is the Phase 2 figure, labelled as the Phase 3 trial. ATTAIN-1 reported −11.2% at 36 mg.
Citing this page.
This table may be reproduced with attribution. Please cite the underlying trial for any individual figure — the papers are linked in the table — and link here for the compilation.
Peptide Prime. “Weight-Loss Drug Trial Data.” Updated 4 August 2026. https://getpeptideprime.com/compare/weight-loss-drug-trial-data
Four of the nine figures here are not yet verified against a primary publication and are marked as such — do not cite those from this page. The verified figures are means across trial populations, and individual results vary widely around them. Cross-trial comparison is unreliable: only SURMOUNT-5 tested any of these compounds against another directly. Trials also enrol supervised participants with lifestyle support, so results do not transfer cleanly to unsupervised use, and most of these compounds are not approved for weight management at all. This page reports what trials measured. It does not recommend anything, and the highest number is not automatically the best choice.