On 20 August 2026 the New England Journal of Medicine published SYNCHRONIZE-1, the first phase 3 obesity result for survodutide — a weekly injection that activates the glucagon and GLP-1 receptors, made by Boehringer Ingelheim. Within days the number in its abstract was being set against tirzepatide's, and the comparison being drawn from it is the wrong one.
This page reports the new trial, compares it with tirzepatide as carefully as separate trials allow, and explains why one line in the survodutide results — the placebo arm — does more to shape the comparison than the drug arms do.
Survodutide is not approved and cannot be prescribed. We report trials and regulatory facts and do not tell anyone what to take; our editorial standards explain why.
What SYNCHRONIZE-1 found
725 adults with a BMI of 30 or more, or 27 or more with at least one obesity-related condition, type 2 diabetes excluded. Mean age 47.1, mean BMI 37.9, mean weight 108.8 kg, 40.6% men. Randomised 1:1:1 to weekly subcutaneous survodutide titrated up to 3.6 mg, up to 6.0 mg, or placebo, for 76 weeks (NCT06066515).
| At week 76 | Survodutide 3.6 mg (n=241) | Survodutide 6.0 mg (n=242) | Placebo (n=242) |
|---|---|---|---|
| Mean weight change | −12.2% (95% CI −13.6 to −10.8) | −13.0% (95% CI −14.4 to −11.6) | −5.4% (95% CI −6.9 to −4.0) |
| Lost ≥5% | 72.6% | 71.9% | 46.3% |
| Gastrointestinal adverse events | 80.9% | 89.7% | 47.9% |
All comparisons with placebo were significant at P<0.001. No deaths were reported. The primary analysis used a treatment-regimen estimand, which counts participants who stopped the drug, used prohibited obesity medicines, or needed a prolonged escalation — a conservative choice that lowers the headline number relative to trials reporting an efficacy estimand.
The line everyone will skip
Placebo groups in obesity trials are not idle. They get the same diet counselling, the same visits, the same scales. They usually lose a little weight: 2.1% in orforglipron's pivotal trial, 3.1% in SURMOUNT-1, 2.4% in STEP 1.
SYNCHRONIZE-1's placebo group lost 5.4%.
That is roughly double the usual figure, and it changes the arithmetic of every cross-trial comparison this drug will be put into:
| Trial | Drug arm | Placebo arm | Placebo-adjusted difference |
|---|---|---|---|
| SYNCHRONIZE-1 | Survodutide 6.0 mg, −13.0% | −5.4% | 7.6 points |
| SYNCHRONIZE-1 | Survodutide 3.6 mg, −12.2% | −5.4% | 6.8 points |
| Foundayo label, Trial 1 | Orforglipron 17.2 mg, −11.1% | −2.1% | 9.0 points |
| SURMOUNT-1 | Tirzepatide 15 mg, −20.9% | −3.1% | 17.8 points |
| SURMOUNT-1 | Tirzepatide 5 mg, −15.0% | −3.1% | 11.9 points |
Read on raw percentages, survodutide (−13.0%) looks stronger than orforglipron (−11.1%). Read against each trial's own control, it is weaker: 7.6 points against 9.0. The orforglipron figure is not our arithmetic — it is printed on the Foundayo label as the difference from placebo, which confirms the subtraction is the one the regulator uses.
None of this makes survodutide a bad drug or the trial a bad trial. A strong placebo response usually means the trial did its supporting care well. It does mean that anyone quoting "13%" beside tirzepatide's "20.9%" is comparing two numbers that were measured against different baselines.
And the caution stands in both directions: placebo-adjusting makes cross-trial figures less misleading, not reliable. Only randomising people between two drugs does that, and nobody has.
The dose finding that deserves attention
Doubling survodutide from 3.6 mg to 6.0 mg added 0.8 percentage points of weight loss. Over the same step, gastrointestinal adverse events rose from 80.9% to 89.7% of participants.
That is a flat top of the dose-response curve with a rising harm curve underneath it — a pattern that argues the useful range sits at or below 3.6 mg. It is also the opposite of what the two approved competitors showed: tirzepatide's SURMOUNT-1 and orforglipron's pivotal trial both had weight loss still climbing at the highest dose tested. If survodutide reaches a label, this is the finding that will shape its dosing.
How the mechanisms differ
| Receptors activated | Status | |
|---|---|---|
| Survodutide | Glucagon + GLP-1 | Investigational, no approval anywhere |
| Tirzepatide | GIP + GLP-1 | Approved: Zepbound, Mounjaro |
| Semaglutide | GLP-1 | Approved: Wegovy, Ozempic, Wegovy tablets |
| Retatrutide | GIP + GLP-1 + glucagon | Investigational, phase 3 |
Survodutide and tirzepatide are both dual agonists, and neither one's second receptor is the other's. The glucagon receptor is the interesting part of survodutide's design — glucagon activity is expected to raise energy expenditure — and it is shared with retatrutide, which our retatrutide vs tirzepatide page covers.
What else survodutide has published
A second phase 3, SYNCHRONIZE-MASLD, in adults with obesity and metabolic dysfunction-associated steatotic liver disease, appeared in Nature Medicine in 2026; an author correction to it was published on 2026-08-25. Two further phase 3 trials, SYNCHRONIZE-CN in China and SYNCHRONIZE-JP in Japan, have published their designs and baseline characteristics but not their results.
None of that is an approval. Until a regulator reviews the whole package, survodutide is a molecule with promising trial data and no label — and material sold under its name is not the material in the trial.
Sources
- le Roux CW et al. Survodutide Once Weekly for the Treatment of Adults with Obesity. N Engl J Med 2026;395(8):776-787. PubMed 42253238 · SYNCHRONIZE-1, NCT06066515
- Survodutide in adults with obesity and metabolic dysfunction-associated steatotic liver disease: SYNCHRONIZE-MASLD. Nat Med 2026. PubMed 42252333; author correction PubMed 42642663
- SYNCHRONIZE-CN design and baseline characteristics, Diabetes Ther 2026. PubMed 42599381; SYNCHRONIZE-JP, Diabetes Obes Metab 2026. PubMed 42219222
- FOUNDAYO prescribing information via the openFDA label API, label effective 2026-07-29, Table 6 (the −9.0 placebo-adjusted difference at 17.2 mg).
- SURMOUNT-1 and STEP 1 figures as cited on our tirzepatide vs semaglutide page.