The TRIUMPH program finished its four registrational trials between December 2025 and July 2026. The retatrutide phase 3 results reported mean weight reductions ranging from 20.8% to 28.7%, depending on the population studied. Retatrutide is still an investigational compound: it is not approved by the FDA, EMA, INVIMA or any other regulatory agency.
What retatrutide does at the mechanism level
Retatrutide is a single agonist at three receptors: GLP-1, GIP and glucagon. Each one contributes a distinct pathway (satiety and gastric emptying, nutrient handling, and hepatic energy expenditure, respectively), and the molecule is designed so that the GLP-1 component offsets the hyperglycemic effect of glucagon.
The full rationale for why receptors get added, and what changes with each one, is in the article on the GLP-1 class.
Before any of the retatrutide phase 3 results, there was a phase 2 trial, published in the New England Journal of Medicine in 2023: 338 participants with obesity, 48 weeks, a mean reduction of 24.2% in the 12 mg group. That was the result that put the molecule on the map, and it drove much of the interest that exists today.
TRIUMPH-4 (December 2025): obesity with knee osteoarthritis
The first trial to report studied a specific population: adults with obesity and knee osteoarthritis.
- Duration: 68 weeks.
- Weight outcome: mean reduction of 28.7% with 12 mg.
- Beyond weight, the trial measured relief from joint pain.
It is the highest weight figure in the program, but it is not comparable to the rest: different population, different duration. A 68-week trial producing a bigger number than an 80-week trial is a reminder that cross-trial comparisons do not mean what they appear to mean.
TRIUMPH-1 (May 2026): the general obesity population
The main registrational trial in obesity without diabetes.
- Randomized participants: 2,339.
- Duration: 80 weeks.
- Doses: 4, 9 and 12 mg, escalated every four weeks, against placebo.
| Group | Mean weight reduction at 80 weeks |
|---|---|
| Retatrutide 4 mg | 17.6% |
| Retatrutide 9 mg | 23.7% |
| Retatrutide 12 mg | 25.0% |
| Placebo | 3.9% |
In a prespecified extension, 532 participants with a BMI ≥35 who tolerated their assigned dose were escalated to the maximum tolerated dose. At 104 weeks, that subgroup reached up to 30% reduction.
That 30% circulates widely and deserves context. It comes from a selected subgroup (participants who tolerated the drug and had a BMI ≥35), measured at 104 weeks, not from the trial as a whole at 80 weeks.
Adverse effects and discontinuations
| Highest dose | |
|---|---|
| Nausea | 42.4% |
| Diarrhea | 32.0% |
| Constipation | 26.1% |
| Vomiting | 25.3% |
| Dysesthesia and urinary tract infections | ~10% |
Discontinuations due to adverse effects rose with the dose: 4.1% at 4 mg, 6.9% at 9 mg and 11.3% at 12 mg, against 4.9% on placebo.
One in nine participants on the high dose stopped because they could not tolerate it. That number belongs in the same sentence as the 25%.
TRIUMPH-2 (July 2026): obesity with type 2 diabetes
- Randomized participants: 1,152, in a 1:1:1:1 ratio to 4 mg, 9 mg, 12 mg or placebo.
- Duration: 80 weeks.
- Weight outcome: up to 20.8% mean reduction (49.6 pounds).
- The trial also measured improvement in glycated hemoglobin (A1C).
The figure is markedly lower than in TRIUMPH-1, and it is not an anomaly: it is a known pattern across the whole class. People with type 2 diabetes consistently lose less weight on incretin agonists than people without diabetes, with the same molecule at the same dose. Comparing the 25.0% from TRIUMPH-1 against the 20.8% from TRIUMPH-2 as if they measured the same thing is exactly the error this section is meant to prevent.
TRIUMPH-3 (July 2026): severe obesity with cardiovascular disease
The most compromised population in the program: adults with severe obesity and established cardiovascular disease, with or without type 2 diabetes.
- Duration: 80 weeks.
- Weight outcome: up to 22.6% mean reduction (55.8 pounds).
On cardiovascular risk factors, the highest dose reported mean reductions of:
| Marker | Mean reduction |
|---|---|
| Triglycerides | 37.0% |
| Non-HDL cholesterol | 16.5% |
| Systolic blood pressure | 9.3 mmHg |
| Waist circumference | 19.0 cm |
| High-sensitivity C-reactive protein (hsCRP) | 51.2% |
And here is the number almost nobody mentions. TRIUMPH-3 also recorded major adverse cardiovascular events (MACE), and neither the three-component composite nor the five-component composite reached statistical significance.
Put plainly: the trial improved risk markers, but it did not show that retatrutide reduces cardiovascular events. Those are two different claims, and the second one is what matters clinically. A marker that improves is a hypothesis; an event that does not happen is a result.
One fair qualification in the other direction. TRIUMPH-3 was not designed primarily as a cardiovascular outcomes trial, and those analyses usually need more participants and more time to be adequately powered. Failing to reach significance is not the same as demonstrating the absence of an effect. It means that with these data the benefit cannot be asserted.
What is still unknown
There is no peer-reviewed publication of the four trials. All the retatrutide phase 3 results above come from sponsor communications and conference presentations. A topline is a summary chosen by whoever funded the study; the full publication includes what does not fit in a press release, and it lets independent reviewers examine the methods.
The dedicated cardiovascular outcomes trial is still running. That is the one that would answer the question TRIUMPH-3 left open.
Maintenance is unresolved. As with the rest of the class, the question of what happens when treatment stops has no published phase 3 answer for this molecule. What is known from the STEP-1 extension with semaglutide, substantial weight regain after withdrawal, does not transfer directly, but it is not reassuring either.
The composition of the weight lost. The proportion of lean mass versus fat mass within the total reduction is a recognized limitation of the class, and it has not been characterized in detail for retatrutide in phase 3.
The realistic regulatory calendar
Eli Lilly has stated that it intends to file its licensing application with the FDA in the first quarter of 2027.
From there, the usual path runs to months of review, and an approval in the United States does not imply simultaneous approval in the European Union or in Colombia. These are independent processes, each on its own calendar. The article on regulatory status explains how each one works.
Until an agency rules, retatrutide remains a research compound. You can check the technical sheet for the 10 mg reference or the 30 mg one for the analytical data on each lot.
Frequently asked questions
When will retatrutide be approved?
There is no date. Lilly has stated that it will file its application with the FDA in the first quarter of 2027; from that point it depends on the agency's review. Any specific date circulating before a regulatory decision is speculation.
Why did TRIUMPH-2 give a lower percentage than TRIUMPH-1?
Because it studied a population with type 2 diabetes, and the entire class of incretin agonists produces less weight reduction in that population. It is a consistent pattern, not a failure of the trial.
Does retatrutide reduce cardiovascular risk?
With current data, that cannot be asserted. TRIUMPH-3 improved several risk markers, but the major adverse cardiovascular event composites did not reach statistical significance. The dedicated outcomes trial is still running.
Is the 30% reduction the trial's real figure?
It is a subgroup figure: participants with a BMI ≥35 who tolerated their dose and were escalated to the maximum tolerated dose, measured at 104 weeks. The result for the trial as a whole at 80 weeks was 25.0% with 12 mg.
Can it be compared with tirzepatide?
Not directly. No head-to-head trial between retatrutide and tirzepatide exists. Comparing figures from trials with different populations, durations and estimands produces conclusions the data do not support.
References
- Jastreboff AM, et al. Triple–Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. New England Journal of Medicine, 2023;389:514–526. DOI: 10.1056/NEJMoa2301972
- Eli Lilly and Company. Lilly's triple agonist, retatrutide, delivered weight loss of up to an average of 71.2 lbs along with substantial relief from osteoarthritis pain in first successful Phase 3 trial (TRIUMPH-4). investor.lilly.com
- Phase III retatrutide study demonstrates 30% weight loss (TRIUMPH-1). The Pharmaceutical Journal, May 21, 2026. pharmaceutical-journal.com
- Eli Lilly and Company. Lilly's triple agonist, retatrutide, successful in two additional Phase 3 obesity trials, delivering significant improvements in weight and A1C (TRIUMPH-2 and TRIUMPH-3). investor.lilly.com
- TRIUMPH Data: Retatrutide Yields Up to 22.6% Weight Reduction in Obesity. The Cardiology Advisor. thecardiologyadvisor.com
Written by the Bionic Editorial Team. Last reviewed: August 2026.
How we work: our editorial policy and source hierarchy.
These figures come from clinical research protocols conducted under medical supervision. They are not a usage recommendation, nor a protocol applicable outside that context.
This content is strictly educational and does not constitute medical advice, diagnosis or a therapeutic recommendation. The compounds mentioned are research products (Research Use Only) and are not approved by INVIMA, FDA, EMA or ANSM for therapeutic use in humans. Any health-related decision should be made with a licensed medical professional.