Biohacking Kompakt

Peptide & Experimental

Survodutide

GLP-1 / glucagon dual agonist · BI 456906

Survodutide is Boehringer Ingelheim’s dual agonist: it activates the GLP-1 and the glucagon receptor. What is remarkable is less the weight loss than the effect on fatty liver, which apparently cannot be explained by weight loss alone. It is not approved.

In short

Survodutide is injected once a week and acts on two receptors: GLP-1 dampens appetite, glucagon acts directly on liver metabolism. In the phase 3 trial SYNCHRONIZE-1 with 725 participants, people lost 12.2 and 13.0 percent of their weight after 76 weeks, versus 5.4 percent on placebo. In a second phase 3 trial in fatty liver disease, 84.2 percent had at least 30 percent less liver fat, versus 24.3 percent on placebo. The price is tolerability: up to 89.7 percent had gastrointestinal complaints. The cardiovascular trial has been completed; its results have not yet been published.

What it is

Survodutide, development name BI 456906, is a peptide from Boehringer Ingelheim that activates two receptors simultaneously: the one for GLP-1 and the one for glucagon. It is injected under the skin once a week and is being tested in two directions, in obesity and in fatty liver disease.

Of the dual agonists of this type, survodutide is the most advanced in the West. The phase 3 trials on weight loss have been completed, as have a trial in fatty liver disease and a large cardiovascular safety trial. For the liver, two further phase 3 trials with 1,800 and 1,590 planned participants are underway, one of them in liver cirrhosis.

How it is supposed to work

The GLP-1 component is familiar: less appetite, better insulin response, slower gastric emptying. The glucagon component is the reason this substance is interesting for the liver. Glucagon acts directly on the liver cell and mobilizes energy there.

Exactly this separation was examined by a post hoc analysis of the phase 2 trial in steatohepatitis with 170 participants and paired tissue samples. The question was how much of the liver effect is simply due to people losing weight. Result: for the resolution of steatohepatitis, the share mediated by weight was 66.7 percent, but for the improvement of fibrosis only 36.3 percent. For markers of inflammation and fibrosis it was below 50 percent, for markers of fat accumulation higher, at 58.2 and 77.4 percent.

In substance this means: fat loss in the liver largely follows weight loss, but the effect on inflammation and scarring apparently does not. The authors consider this an indication of an independent effect of the glucagon component in the liver. It remains a post hoc analysis, but one that answers a concrete question.

How strong the effect is

In SYNCHRONIZE-1, 725 adults with obesity without diabetes were allocated to two dose levels and placebo for 76 weeks. Mean baseline weight was 108.8 kilos, BMI 37.9. Both primary endpoints were met: 12.2 and 13.0 percent weight loss versus 5.4 percent on placebo, and at least 5 percent loss in 72.6 and 71.9 percent versus 46.3 percent.

The placebo value is strikingly high. 5.4 percent loss without active drug and 46.3 percent of the placebo group with at least 5 percent loss are well above what studies in this class usually show. This narrows the difference the drug makes, even if it is statistically clear.

The phase 2 trial with 386 treated participants over 46 weeks showed clear dose dependence: 6.2, 12.5, 13.2 and 14.9 percent loss versus 2.8 percent on placebo. In a meta-analysis of 18 treatment arms with 1,029 participants, the pooled weight loss was 8.33 kilos, though with a heterogeneity of 99.6 percent, which makes the figure hardly interpretable.

What is well supported

The weight loss is supported by a phase 3 trial with 725 participants over 76 weeks, with primary endpoints met and a clear gap to placebo. The phase 2 trial with 386 treated participants over 46 weeks shows dose dependence up to 14.9 percent loss.

The liver effect is better supported than for competing substances. In SYNCHRONIZE-MASLD with 216 participants over 48 weeks, both co-primary endpoints were met: at least 30 percent less liver fat on magnetic resonance measurement was achieved by 84.2 percent of those treated versus 24.3 percent on placebo. Including treatment discontinuations, the figures are 68.5 versus 28.6 percent. Both figures are statistically clear, and the difference between them shows how much depends on the method of calculation.

In addition there are documented side effects in the good sense: better blood pressure in a post hoc analysis of the phase 2 trial, better markers of beta-cell function and insulin sensitivity, and lower waist circumference and BMI in the meta-analysis. And no deaths were reported in SYNCHRONIZE-1.

What the studies show

SYNCHRONIZE-1 (NEJM 2026)

Phase 3, double-blind, 725 participants with obesity without diabetes, two dose levels versus placebo over 76 weeks, mean age 47.1 years. Both primary endpoints met: 12.2 and 13.0 percent weight loss versus 5.4 percent; at least 5 percent loss in 72.6 and 71.9 percent versus 46.3 percent. Gastrointestinal complaints in 80.9 and 89.7 percent versus 47.9 percent. No deaths. Funded by Boehringer Ingelheim.

SYNCHRONIZE-MASLD (Nature Medicine 2026)

Phase 3 in obesity with at-risk fatty liver disease, 216 participants in a 2 to 1 ratio, 48 weeks. Both co-primary endpoints met: at least 30 percent less liver fat in 84.2 versus 24.3 percent and weight loss of 12.2 versus 1.0 percent; including discontinuations, 68.5 versus 28.6 percent and 8.7 versus 1.4 percent. As limitations, the authors cite the short duration and participation from only two countries.

Phase 2 dose finding (Lancet Diabetes Endocrinol 2024)

43 centers in 12 countries, 386 treated participants, four dose levels versus placebo over 46 weeks. Primary endpoint met, loss of 6.2, 12.5, 13.2 and 14.9 percent versus 2.8 percent. Only 233 of 386 participants, that is 60.4 percent, completed the 46 weeks, similarly in active and placebo groups. Side effects in 91 percent on active drug versus 75 percent on placebo.

Mediation analysis on the liver (Hepatology 2026)

Post hoc analysis of the phase 2 trial in steatohepatitis, 170 participants with fibrosis stage F2 to F3 and paired tissue samples. The share of the effect mediated by weight loss was 66.7 and 71.8 percent for the steatohepatitis endpoints, 36.3 percent for the improvement of fibrosis and below 50 percent for markers of inflammation and fibrosis.

Where the data stop

Tolerability is the weak point of this substance. In the phase 3 trial, 80.9 and 89.7 percent had gastrointestinal complaints, versus 47.9 percent on placebo. In the phase 2 trial only 60.4 percent completed the 46 weeks, equally in active and placebo groups. We do not give specific discontinuation rates due to side effects, because the abstracts do not report any, the full texts were not accessible and no results have been posted in the trial registry.

The most important open question is the heart. The large cardiovascular safety trial with 5,531 participants has been listed as completed since the end of June 2026, but results have been neither posted in the registry nor published. Until then, it remains open what survodutide means for heart attack, stroke and mortality. Glucagon/GLP-1 dual agonists increase heart rate, according to a review to a similar extent as pure GLP-1 drugs, and at least one other dual agonist was discontinued partly because of excessive heart rate increases and QT prolongation.

For the liver, endpoint data are still missing: the two phase 3 trials with 1,800 and 1,590 planned participants are only now recruiting. A head-to-head comparison with semaglutide or tirzepatide has not been published. And the figures visibly depend on how they are calculated: in the fatty liver trial, 12.2 percent weight loss stands next to 8.7 percent, depending on the estimation method. The larger value is reliably the one advertised. There is no approval anywhere.

Status, approval and legal

Survodutide is an investigational drug from Boehringer Ingelheim and is not approved anywhere; in Germany it is not a marketable medicine and is not available outside of trials. We therefore give no dosing information. Completed are the phase 3 trials in obesity with and without type 2 diabetes, the trials in Japan and China, the fatty liver trial SYNCHRONIZE-MASLD and the cardiovascular trial with 5,531 participants, whose results are not yet available. Currently recruiting are the liver endpoint trials with 1,800 and 1,590 planned participants and a trial in type 2 diabetes with 600 participants. In sport: the catch-all class S0 of the 2026 Prohibited List bans drugs in clinical development at all times, and by this wording survodutide falls under it.

Safety

Gastrointestinal complaints are very common and the most important reason why this substance is not suitable for everyone: in the phase 3 trial in 80.9 and 89.7 percent versus 47.9 percent on placebo, mostly mild to moderate and more frequent during dose escalation. In the phase 2 trial, 91 percent on active drug had some side effect versus 75 percent on placebo, mostly gastrointestinal, and only 60.4 percent completed the 46 weeks, similarly in both arms. No deaths were reported in SYNCHRONIZE-1. Like other glucagon/GLP-1 dual agonists, survodutide increases heart rate; cardiovascular safety is being examined in a dedicated trial and a thorough QT study, and results are not available. There are no upper limits from EFSA, BfR or NIH, because this is not a nutrient. Pregnancy, breastfeeding, and children and adolescents have not been studied. Outside a trial, survodutide is not available, and gray market products are untested.

BK-Score Well supported, heavily overhyped

Human evidence8
Mechanism8
Safety data6
Hype gap4
Track record of use3

SYNCHRONIZE-1 (NEJM 2026) randomized 725 participants over 76 weeks: 12.2 to 13.0 percent weight reduction versus 5.4 percent on placebo, both primary endpoints met. Notable is the high placebo response, which makes the gap smaller. SYNCHRONIZE-MASLD (Nat Med 2026, 216 participants, 48 weeks) met both co-primary endpoints: at least 30 percent less liver fat in 84.2 versus 24.3 percent, and according to the mediation analysis of the phase 2 MASH trial, the effect on inflammation and fibrosis is predominantly not mediated by weight loss – the strongest point of this substance. The striking value is in the safety column: gastrointestinal complaints in 80.9 and 89.7 percent versus 47.9 percent on placebo, and in the phase 2 trial only 60.4 percent completed the 46 weeks, similarly in active and placebo groups. Specific discontinuation rates due to side effects are not publicly available (full texts not accessible, no registry results). Dual glucagon and GLP-1 receptor agonism is confirmed in humans. Equivalence with tirzepatide is advertised, although no head-to-head comparison has been published; the results of the completed cardiovascular trial with 5,531 participants are also missing.

The score rates the state of knowledge, not the substance. “Safety data 9” means well studied – not harmless.
Subjective assessment by Biohacking Kompakt based on published scoring rules – not a scientific rating and not a medical recommendation. Rules and all ratings (German)

Frequently asked questions about Survodutide

How much weight do you lose with survodutide?

In the phase 3 trial over 76 weeks it was 12.2 and 13.0 percent of body weight, versus 5.4 percent on placebo. In the phase 2 trial over 46 weeks, depending on the dose, 6.2 to 14.9 percent versus 2.8 percent.

Does survodutide help against fatty liver?

In a phase 3 trial with 216 participants, after 48 weeks 84.2 percent had at least 30 percent less liver fat, versus 24.3 percent on placebo. The trials on hard liver endpoints are only now underway.

Does the liver effect work only through weight loss?

Apparently not entirely. In a post hoc analysis, the improvement in fibrosis was only 36.3 percent mediated by weight loss, and for markers of inflammation and fibrosis below 50 percent. Fat loss in the liver, by contrast, largely follows weight loss.

Is survodutide as good as tirzepatide?

That cannot be said. There is no published head-to-head comparison. Striking is the high placebo response in the phase 3 trial with 5.4 percent loss, which makes the gap to the active drug look smaller.

How well tolerated is survodutide?

Worse than one would wish. In the phase 3 trial, up to 89.7 percent had gastrointestinal complaints, versus 47.9 percent on placebo. In the phase 2 trial only 60.4 percent completed the 46 weeks, though equally in the active and placebo groups.

Is survodutide already approved?

No, not anywhere. The phase 3 trials on weight loss and fatty liver have been completed, as has the cardiovascular trial with 5,531 participants, but its results have not yet been published.

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Information only, not medical advice and not a usage or dosage recommendation. Prescription-only and unapproved substances belong in the hands of a physician. Last updated: 2026-09-30.