May 2026 update: On May 21, 2026, Eli Lilly reported results from TRIUMPH-1 — the first Phase 3 trial of retatrutide in general obesity (without diabetes or knee osteoarthritis). People on the highest dose lost up to 28.3% of their body weight over 80 weeks. A subset of participants with BMI ≥35 that continued to 104 weeks reached 30.3% weight loss (85 lbs) — the highest average weight loss reported in any Phase 3 obesity trial to date. But retatrutide is still not FDA-approved and not available at any pharmacy.
Retatrutide is one of the most talked-about weight-loss drugs that is not on the market yet. That matters. People hear about it online, see dramatic claims, and assume it is just another version of Ozempic or Mounjaro. It is not. Retatrutide is a different drug that is still investigational — but it now has three successful Phase 3 trials behind it, and the weight loss numbers are the highest seen in any obesity drug trials to date.
What retatrutide is
Retatrutide is a next-generation drug being studied for obesity and metabolic health. It is made by Eli Lilly. It works on three pathways:
- GLP-1 — signals fullness, slows digestion
- GIP — works with GLP-1 to boost the effect
- glucagon — increases energy expenditure (burns more calories)
That is why people call it a triple agonist. It is the first drug in this category to target all three receptors at once.
Does retatrutide have a brand name?
No approved retail brand name at this time. That is one of the easiest ways to tell retatrutide apart from semaglutide and tirzepatide.
Semaglutide brand names
- Ozempic
- Wegovy
- Rybelsus
Tirzepatide brand names
- Mounjaro
- Zepbound
Retatrutide brand names
- none approved yet
TRIUMPH-1 results: the general obesity Phase 3 trial
On May 21, 2026, Lilly announced top-line results from TRIUMPH-1 — the Phase 3 trial for general obesity. This is the trial people have been waiting for, because it tests retatrutide in the broadest obesity population (not limited to people with knee osteoarthritis or diabetes).
TRIUMPH-1 primary results at 80 weeks
The trial ran for 80 weeks in adults with obesity who did not have diabetes.
| Retatrutide 4 mg | Retatrutide 9 mg | Retatrutide 12 mg | Placebo | |
|---|---|---|---|---|
| Weight loss (efficacy estimand) | −19.0% (47.2 lbs) | −25.9% (64.4 lbs) | −28.3% (70.3 lbs) | −2.2% (5.5 lbs) |
| Weight loss (treatment-regimen estimand) | — | — | −25.0% | — |
What those terms mean:
- Efficacy estimand — measures the drug's effect assuming people stay on it (includes data regardless of whether people stopped early, using statistical methods to account for dropouts)
- Treatment-regimen estimand — measures what actually happened to people who took the drug as directed, including those who stopped
Key secondary endpoints at 80 weeks
| Retatrutide 4 mg | Retatrutide 9 mg | Retatrutide 12 mg | Placebo | |
|---|---|---|---|---|
| Reached ≥25% weight loss | 27.8% | 52.9% | 62.5% | 2.2% |
| Reached ≥30% weight loss | 15.3% | 37.9% | 45.3% | 0.5% |
| Reached ≥35% weight loss | 5.9% | 20.8% | 27.2% | 0.3% |
| Waist circumference reduction | −6.4 in | −8.6 in | −9.5 in | −1.4 in |
The 12 mg dose moved 65.3% of participants below a BMI of 30 — including 37.5% of those who started with class 3 obesity (BMI ≥40).
Extension to 104 weeks (BMI ≥35 participants who continued)
| 4 mg to MTD | 9 mg to MTD | 12 mg to MTD | Placebo to MTD | |
|---|---|---|---|---|
| Weight loss at 104 weeks | −27.9% (73.3 lbs) | −29.5% (80.7 lbs) | −30.3% (85.0 lbs) | −19.2% (49.9 lbs) |
The 30.3% average weight loss at 104 weeks is the highest average weight loss reported in any Phase 3 obesity trial to date. The 45.3% of 12 mg participants reaching ≥30% weight loss is a level previously associated with bariatric surgery outcomes.
Cardiometabolic improvements
TRIUMPH-1 also showed improvements in cardiovascular risk factors:
- Reductions in non-HDL cholesterol
- Reductions in triglycerides
- Reductions in systolic blood pressure
- Reductions in hsCRP (a marker of inflammation)
All three Phase 3 trials now show improvements in cardiovascular risk factors like blood pressure, cholesterol, and inflammation markers.
Safety and tolerability in TRIUMPH-1
Discontinuation due to adverse events by dose:
| Retatrutide 4 mg | Retatrutide 9 mg | Retatrutide 12 mg | Placebo | |
|---|---|---|---|---|
| Discontinued due to side effects | 3.0% | 6.1% | 11.3% | 4.9% |
At the 4 mg dose, fewer people stopped treatment than on placebo — an unusual finding that may reflect the lower gastrointestinal burden at this dose. At the 12 mg dose, 11.3% stopped due to side effects (primarily gastrointestinal issues). Some discontinuations at higher doses were because participants felt they had lost too much weight.
Retatrutide vs Zepbound vs Wegovy vs CagriSema: direct comparison table
The table below compares Phase 3 obesity trial results across these four drugs. Important caveat: these are cross-trial comparisons, not head-to-head studies. Each trial enrolled different populations, used different durations, and measured endpoints differently. Direct numerical comparison should be interpreted with caution.
| Retatrutide (TRIUMPH-1) | Zepbound (SURMOUNT-1) | Wegovy (STEP 1) | CagriSema (REDEFINE 1) | |
|---|---|---|---|---|
| Mechanism | Triple agonist (GLP-1 + GIP + glucagon) | Dual agonist (GLP-1 + GIP) | GLP-1 only | Dual (GLP-1 + amylin) |
| Trial duration | 80 weeks (extension to 104) | 72 weeks | 68 weeks | 68 weeks |
| Highest dose weight loss | 28.3% (70.3 lbs) | ~22.5% | ~15% | 20.4% |
| Extension/longer-term | 30.3% at 104 wks (BMI ≥35) | — | — | — |
| % reaching ≥30% weight loss | 45.3% (12 mg) | ~30% (15 mg) | ~12% (2.4 mg) | Not reported |
| FDA status | Not yet filed; Phase 3 ongoing | Approved (2023) | Approved (2021) | Under FDA review; decision expected late 2026/early 2027 |
| Current availability | Not available — investigational | Available by prescription | Available by prescription | Not available — under review |
Key limitations of this comparison:
- Different trial populations (TRIUMPH-1 excluded diabetes; SURMOUNT-1 and STEP 1 had different inclusion criteria)
- Different trial durations (68–80 weeks for primary endpoints)
- Different statistical methods and estimand frameworks
- SURMOUNT-1 and STEP 1 used earlier estimand approaches; TRIUMPH-1 used a treatment-policy–style estimand consistent with more recent FDA guidance
- CagriSema's REDEFINE 1 used a different comparator design
These numbers give a general sense of relative efficacy, but no drug can be definitively ranked against another without a head-to-head trial.
Other Phase 3 trial results
TRIUMPH-4 (obesity with knee osteoarthritis)
Results reported December 2025. Adults with obesity and knee osteoarthritis.
| Retatrutide 9 mg | Retatrutide 12 mg | Placebo | |
|---|---|---|---|
| Weight loss at 72 weeks | −22.3% | −28.7% | −1.8% |
TRANSCEND-T2D-1 (type 2 diabetes)
Results reported March 2026. Adults with type 2 diabetes.
| Retatrutide 4 mg | Retatrutide 9 mg | Retatrutide 12 mg | Placebo | |
|---|---|---|---|---|
| Weight loss | −9.1% | −14.5% | −17.0% | −2.4% |
| A1C reduction | −1.8% | −2.1% | −2.2% | −0.4% |
What does the glucagon part mean?
This is where articles often get too technical. The simple version is:
Retatrutide is being studied as a more aggressive metabolic drug. The glucagon receptor increases energy expenditure — meaning your body burns more calories even at rest. That is on top of the fullness and appetite signals from GLP-1 and GIP.
That does not automatically mean better for everyone. It means the drug is trying to affect the body in a broader way than semaglutide or tirzepatide alone.
Side effects and safety
The most common side effects in the Phase 3 trials were the same ones you see with other GLP-1 drugs:
- nausea
- diarrhea
- constipation
- vomiting
- decreased appetite
These were mostly mild to moderate and happened most during dose increases.
A new side effect worth knowing about
The trials also reported dysesthesia — a tingling, burning, or numb sensation, usually mild. This showed up in all three Phase 3 trials:
- TRIUMPH-1: 20.9% at 12 mg (vs 4.9% placebo discontinuation overall)
- TRIUMPH-4: 8.8% (9 mg) and 20.9% (12 mg) vs 0.7% with placebo
- TRANSCEND-T2D-1: 2.3% to 4.5% vs 0% with placebo
Most cases were mild and did not cause people to stop the drug. But this is a new signal that researchers are watching.
Discontinuation rates across trials
| Trial | Lowest dose | Highest dose | Placebo |
|---|---|---|---|
| TRIUMPH-1 (general obesity) | 3.0% (4 mg) | 11.3% (12 mg) | 4.9% |
| TRIUMPH-4 (knee OA) | 12.2% (9 mg) | 18.2% (12 mg) | 4.0% |
| TRANSCEND-T2D-1 (diabetes) | 2.2% (4 mg) | 5.1% (12 mg) | 0% |
In TRIUMPH-4, some discontinuations were because participants felt they had lost too much weight. In TRANSCEND-T2D-1, discontinuation was much lower overall.
When could retatrutide become available?
Not now. Not soon. Here is the honest timeline.
Retatrutide now has three successful Phase 3 trials. But the Phase 3 program is not finished. Several more trials are still running, and Lilly needs those results before filing with the FDA.
Here is what the timeline looks like:
- December 2025: TRIUMPH-4 results (obesity + knee osteoarthritis) — positive
- March 2026: TRANSCEND-T2D-1 results (type 2 diabetes) — positive
- May 21, 2026: TRIUMPH-1 results (general obesity) — positive
- June 2026: Detailed TRIUMPH-1 and TRANSCEND-T2D-1 data to be presented at ADA Scientific Sessions in New Orleans
- 2026 (ongoing): Remaining Phase 3 readouts expected, including trials for obstructive sleep apnea, cardiovascular outcomes, and liver disease
- Earliest likely FDA filing: Late 2026 or 2027, after the remaining Phase 3 trials finish — this is an estimate, not a guarantee; Lilly has not announced a specific filing date
- Earliest possible approval: 2027 at the soonest, assuming a timely filing — this is speculative
The FDA review process itself typically takes 6 to 10 months after a filing. Do not make medical decisions based on an assumed approval date.
What to watch next in 2026
A few things that could change the picture:
- ADA Scientific Sessions (June 2026) — Full TRIUMPH-1 data including sleep apnea and osteoarthritis results. This is where we will learn how retatrutide affects conditions beyond weight.
- Remaining Phase 3 trials — Results for sleep apnea, cardiovascular outcomes, and liver disease are expected throughout 2026.
- FDA filing timeline — Watch for any announcement from Lilly about when they plan to submit. That will lock in the earliest possible approval date.
- CagriSema FDA decision — Expected late 2026 or early 2027. If approved, it becomes another competitor in the next-generation GLP space.
Why this article needs caution
Retatrutide content gets weird fast online. You will see:
- hype
- rumor
- people acting like approval already happened
- people talking about it like it is the obvious winner before the dust has settled
The Phase 3 results are genuinely strong. But the smart view is still:
- yes, it is interesting — more than ever
- yes, the trial numbers are real
- no, that does not make every dramatic claim true
- no, you cannot get it at a pharmacy yet
What questions people usually have
Most readers are trying to answer one of these:
- What is retatrutide?
- Is retatrutide better than semaglutide?
- Is retatrutide better than tirzepatide?
- Does retatrutide have a brand name?
- Can you actually get retatrutide yet?
- When will retatrutide be approved?
The clean answer right now: Retatrutide is a triple-agonist investigational drug with strong Phase 3 results in three different patient populations. It does not have an approved brand name yet, and it should not be discussed like it is already just another routine retail GLP medication. The earliest it could reach patients is 2027.
Products That Can Help
Learning about upcoming GLP medications? These products may help you prepare:
- GLP-1 starter guide book — Understand current options while new drugs develop
- Smart scale with body composition — Track progress with current treatments
- Food and weight journal — Document what works for your body
- Protein powder — Support muscle preservation on any GLP medication
GLPSpot may earn from qualifying purchases.
Bottom line
Retatrutide matters because it may represent the next wave of obesity and metabolic drugs. The Phase 3 data now includes three positive trials, and the weight loss numbers are the highest seen in this drug class to date. But right now, the honest way to think about it is:
- it is real
- it is important
- it is in Phase 3 clinical trials (as of May 2026)
- the trial results are strong — up to 28.3% weight loss in general obesity (TRIUMPH-1), 28.7% in obesity with knee osteoarthritis (TRIUMPH-4)
- a subset of patients lost 30.3% of their body weight over 2 years
- it does not have an approved brand name yet
- the earliest possible approval is likely 2027
- do not make medical decisions based on an assumed timeline
If you want to compare it with what is already available, read next:
- Semaglutide Guide: Ozempic, Wegovy, and Rybelsus Explained
- Tirzepatide Guide: Mounjaro and Zepbound Explained
- GLP-1 Medications Explained
- Best GLP-1 for Weight Loss 2026
- Zepbound vs Retatrutide
- Ozempic vs Retatrutide
- Mounjaro vs Retatrutide
- Foundayo (Orforglipron): GLP-1 Pill With No Food Rules
- CagriSema Weight Loss Guide
Disclaimer: This content is for informational purposes only and does not constitute medical advice. Retatrutide is an investigational drug that is not yet approved by the FDA. Talk to your healthcare provider about treatment options that are right for you.
