What changed in trials
Retatrutide results from the published trials.
See the Phase 1b and Phase 2 findings for obesity, type 2 diabetes, fatty liver, and kidney tests. A published paper supplies each number.
How to read retatrutide results without overreading them
Trial reports on retatrutide cover weight loss and diabetes, but the drug remains under study. This page sets the main results in order and explains the numbers. The largest average weight loss was 24.2% over 48 weeks at the highest Phase 2 dose. That careful Phase 2 study did not promise a result for you.
Chance decided who got retatrutide and who got a placebo, or dummy shot. Neither the people in the study nor the staff measuring results knew who had the real drug. The 24.2% figure was one dose group's average. Results still varied from person to person.
Phase 2 can show that a drug has an effect. It cannot settle long-term heart safety or tell whether weight loss endures. Those are jobs for Phase 3. The people behind these numbers had planned clinic checks, unlike someone using an unapproved research vial.
What body weight did in the Phase 2 obesity trial (48 weeks)
The 48-week Phase 2 obesity trial followed 338 adults [1]. A weekly shot was placed in body fat. Average weight lost, set against the placebo group, was:
- 1 mg: 8.7%, against 2.1% on placebo
- 4 mg: 17.3%, against 2.1% on placebo
- 8 mg: 22.8%, against 2.1% on placebo
- 12 mg: 24.2%, against 2.1% on placebo
In the 12 mg group, 63% lost at least 20% of body weight by week 48 [12]. The top blood-pressure number fell by an average 8.79 mmHg [12]. Use these as group figures, never as your forecast.
A 2025 review joined three trials with 878 people. People on the drug lost 14.33% more of their weight on average than people on placebo [8]. Health problems of all kinds, counted together, weren't clearly more common on the drug.
A different 2025 review compared this loss with older drugs and weight-loss surgery [6]. A 2024 paper in the science journal Cell discussed why copying three hormones might bring losses of about 20-30% [9]. Both were reviews, not new direct trials.
What blood sugar did in the Phase 2 type 2 diabetes trial (36 weeks)
A separate 36-week Phase 2 trial followed 281 adults with type 2 diabetes [2]. With 12 mg, HbA1c, which shows average blood sugar, fell by 2.02%, against 0.01% with placebo at 24 weeks. Weight fell by 16.94%, against 3.00% with placebo at 36 weeks. Gut problems were mild or moderate in 35%.
No severe low-blood-sugar event was reported. No death was blamed on retatrutide. Study staff reduced insulin for some people who already used it. The change fits the drug's GLP-1 and GIP actions and took place under study care.
A 2026 review in the heart journal Cardiology in Review gathered the main Phase 2 findings in one place [12]. It noted 24.2% weight loss, with 63% losing at least 20% of total body weight. It also listed a 2.02% fall in HbA1c for diabetes, an 8.79 mmHg blood-pressure drop, and less protein leaking into urine. The review didn't create new trial results.
What liver fat did in the MASLD Phase 2a study (48 weeks)
The smaller Phase 2a study enrolled 98 adults who had MASLD and either obesity or overweight [5]. MASLD is fatty liver linked with problems handling blood sugar and fat. MRI scans showed liver fat of at least 10%, and no one had type 2 diabetes. Changes at 24 weeks were:
- 1 mg: down 42.9%
- 4 mg: down 57.0%
- 8 mg: down 81.4%
- 12 mg: down 82.4%, against a rise of 0.3% on placebo
With 12 mg, 86% got under the normal 5% liver-fat mark by week 24. The drop held through 48 weeks, reaching a drop of 86.0% at 12 mg. A 2026 Frontiers in Medicine review linked the result to changes in liver fat, swelling, and scar tissue [15]. That review can't make the small study more certain.
What changed in the kidney tests
A later look at both Phase 2 trials found three kidney changes [7]:
- Protein leaking into urine fell about 37% with 12 mg in type 2 diabetes.
- That leak fell about 28-31% with 8-12 mg in the obesity group.
- Another kidney blood test improved in the obesity group.
The authors called those early changes good signs. Phase 2 had left out people with a kidney blood-test score below 45, which means more serious kidney trouble. Another trial is still studying people with that illness. Until it reports, the early signs don't settle kidney safety.
What the first Phase 1b human study found (12 weeks)
The first Phase 1b study followed 72 adults with type 2 diabetes for 12 weeks [4]. Its main findings were:
- Half-life was about 6 days, which fit a weekly shot schedule.
- On the highest dose, people lost 8.96 kg more than people on the dummy shot over 12 weeks; the authors gave that result at a 90% level of certainty.
- Daily blood sugar readings came down at the 3 mg dose.
- Health problems appeared in 63%, mostly in the gut; the authors felt the safety result allowed more study.
These retatrutide results are gathered on this one page. The retatrutide vs tirzepatide page compares the separate studies with care. Neither page turns these trial amounts into a personal plan.
What Phase 3 may add to the earlier results
The Phase 2 studies were too small and short to settle years of safety. The Phase 3 TRIUMPH trials follow people for more than two years. They check major heart problems and kidney results in people with long-term kidney disease. They also compare retatrutide with tirzepatide and check how much weight comes back once treatment ends.
Phase 2 showed that the drug had an effect in the people studied. Phase 3 must show whether the benefits hold up and outweigh the risks. Several trial groups expected results in 2026-2027. Only the finished results and FDA review can answer the approval question.