Two of these four molecules are approved medicines and two are not, which is the first and most consequential difference between them. Semaglutide and tirzepatide hold regulatory approvals for type 2 diabetes and for chronic weight management; survodutide and retatrutide remain investigational, and nothing published to date establishes that either is safe or effective for general use. Across the published literature the reported average weight reductions have generally been larger for the multi-receptor agents than for GLP-1 agonism alone, but those figures come from separate trials with different populations, durations, dose ranges, and background care.
No adequately powered head-to-head trial has compared all four agents, so any ranking assembled from cross-trial percentages is a hypothesis rather than evidence.
The four agents form a ladder of receptor engagement, and each added rung reflects a hypothesis about what a second or third pathway would buy. Broader receptor coverage has been associated with larger average weight reductions in early trials, and it also widens the surface for unwanted effects, including the resting heart rate increases reported with the glucagon-containing agents. Mechanism explains why researchers pursued each design; it is not proof that the design works.
All four molecules are engineered for extended half-lives that support once-weekly subcutaneous injection, and they differ in receptor coverage from semaglutide's single GLP-1 target to retatrutide's simultaneous GIP, GLP-1, and glucagon agonism.
Reported figures should be read as trial-specific results, not as a scoreboard. Each number below belongs to one program with its own duration, dose range, and population, and every average conceals a wide distribution in which some participants lost far more and others lost little. Phase 2 findings in particular have historically been attenuated when tested in larger, more heterogeneous phase 3 populations.
| Agent and program | Duration and dose | Reported average reduction |
|---|---|---|
| Semaglutide, pivotal obesity program | 68 weeks, 2.4 mg weekly | Roughly 15 percent of baseline body weight |
| Tirzepatide, obesity program | 72 weeks, dose-dependent | Roughly 15 to 21 percent depending on assigned dose |
| Survodutide, phase 2 obesity study | 46 weeks, 20-week escalation plus 26 weeks maintenance | Approximately 15 percent at the highest dose studied |
| Retatrutide, phase 2 study | 48 weeks, highest dose | Roughly 24 percent |
Retatrutide's 48-week phase 2 study reported average reductions of roughly 24 percent at its highest dose, the largest figure among the four, drawn from a single phase 2 trial that cannot be compared directly with the 46-week, 68-week, and 72-week programs that produced the other numbers.
Randomization is what makes a comparison trustworthy, and it operates only within a single trial. When participants are randomly assigned to drug A or drug B in the same study, at the same sites, under the same protocol, any difference in results can reasonably be attributed to the drugs. None of that holds once two numbers are lifted from two separate publications.
Formal indirect treatment comparisons are labeled by their own authors as hypothesis-generating, and no head-to-head evidence establishes any one of these four agents as superior to another.
Nausea, vomiting, diarrhea, constipation, and reduced appetite dominate the adverse event tables for every drug in this family, and in each program these effects were most frequent during dose escalation, mostly mild to moderate, and generally diminished as participants stabilized on a dose. The sharper asymmetry across the four is not a difference in observed risk but a difference in how much has been observed at all.
Semaglutide and tirzepatide have accumulated large post-approval exposure while the safety databases for survodutide and retatrutide are limited to their trial populations, and absence of a reported signal in a phase 2 study is not the same as an established safety record.
A designation that accelerates review is not an approval, positive phase 2 results are not an approval, and enrollment in phase 3 is not an approval. Before any regulator acts, a sponsor must show sustained benefit on prespecified endpoints in large randomized populations along with an acceptable safety database, and applications at this stage still fail. Pipeline status changes, so any published description of it is a snapshot of the day it was written.
Neither survodutide nor retatrutide is approved or commercially available, and current status for any of these molecules is verifiable only through national regulator databases and public clinical trial registries.
Weight is the headline, and the class is being evaluated on several fronts at once. The liver is contested territory rather than a survodutide monopoly: semaglutide has since been approved in the United States for metabolic dysfunction-associated steatohepatitis in adults with moderate to advanced fibrosis, under the accelerated approval pathway on the basis of biopsy findings.
The approved agents hold the deeper outcome record, including evidence in heart failure with preserved ejection fraction and in chronic kidney disease, while for survodutide and retatrutide the trials measuring hard endpoints over years have not reported.
All four were designed as once-weekly subcutaneous injections, typically self-administered with a prefilled pen into the abdomen, thigh, or upper arm with the site rotated. Semaglutide also exists in a daily oral tablet form, approved both for type 2 diabetes and, at a 25 mg dose, for weight management, which is the main route-level difference among the four. For the two investigational agents the final dosing schedule is not settled, since phase 3 exists in part to determine which dose and escalation pattern best balances benefit against tolerability.
Survodutide's phase 2 program used extended escalation periods of 20 weeks in the obesity trial and 24 weeks of rapid escalation in the liver trial, a difference directly relevant to interpreting its tolerability data, since titration speed shapes how many adverse events are reported.
An investigational medicine has no price because it cannot be sold. That gap is what reliably drives interest in early data toward unregulated sellers offering compounded or research-labeled products of unknown identity, purity, and dose, which carry real risk of contamination, incorrect concentration, and complete absence of clinical oversight.
Survodutide and retatrutide cannot be purchased through pharmacies at any cost, while manufacturer savings programs, employer carve-outs, public program rules, and periodic supply shortages all move what a person pays for the approved agents independent of list price.
The most consistent finding across withdrawal studies in this class is that stopping the medication is followed by substantial regain. That reframes the comparison between these four agents: what matters is not only how much weight an agent produces at week 68, but whether it can be tolerated, afforded, and sustained indefinitely.
Randomized withdrawal data establish obesity as a chronic, relapsing condition rather than a course of therapy with a finish line, and continuous exposure data now extends to several years only for the approved agents.
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