Semaglutide vs Tirzepatide vs Retatrutide
All three belong to the same incretin-receptor drug class, but each activates a different combination of receptors. Here's how the mechanisms, regulatory status, and trial data compare.
KYIN Peptides supplies Retatrutide for laboratory research use. We do not sell semaglutide or tirzepatide — both are patented, FDA-approved prescription pharmaceuticals. They're included here purely for research and educational comparison.
At a Glance
| Semaglutide | Tirzepatide | Retatrutide | |
|---|---|---|---|
| Developer | Novo Nordisk | Eli Lilly | Eli Lilly |
| Receptor targets | GLP-1 only | GIP + GLP-1 (dual agonist) | GIP + GLP-1 + Glucagon (triple agonist) |
| Brand name(s) | Ozempic (diabetes), Wegovy (weight) | Mounjaro (diabetes), Zepbound (weight) | None yet — investigational |
| Regulatory status | FDA-approved | FDA-approved | Phase 3 (TRIUMPH program), not yet approved |
| Key trial result | STEP-1: 14.9% body weight reduction at 68 weeks | SURMOUNT-1: 20.9% body weight reduction at 72 weeks (15mg) | TRIUMPH-4: 28.7% body weight reduction at 68 weeks |
| Available from KYIN Peptides | No | No | Yes |
How the Mechanisms Differ
All three drugs work on the incretin system, but each adds a receptor the previous one doesn't touch. Semaglutide activates the GLP-1 receptor alone — slowing digestion, increasing satiety, and improving insulin secretion. Tirzepatide adds GIP receptor activity on top of GLP-1, and research suggests it actually engages the GIP receptor more strongly than the GLP-1 receptor, which is thought to contribute to its stronger weight-loss results and, in some studies, fewer gastrointestinal side effects compared to semaglutide. Retatrutide goes a step further, adding glucagon receptor activity to the GIP/GLP-1 combination — glucagon's own contribution is increased energy expenditure and hepatic lipid oxidation, which researchers believe is behind retatrutide's larger effect on liver fat specifically. See Retatrutide's full discovery history.
Clinical Trial Data
Semaglutide (STEP program): The STEP-1 trial demonstrated GLP-1 monotherapy delivering a 14.9% mean body weight reduction at week 68 in adults with obesity.
Tirzepatide (SURMOUNT program): In SURMOUNT-1, participants on the highest dose (15mg weekly) lost an average of 20.9% of body weight over 72 weeks, with nearly a third of that group losing more than 25%. In a head-to-head trial, SURMOUNT-5, tirzepatide outperformed semaglutide directly — 20.2% versus 13.7% mean weight reduction.
Retatrutide (TRIUMPH program): Retatrutide's earlier Phase 2 trial (published in the New England Journal of Medicine, 2023) showed 24.2% weight loss at 48 weeks on the highest dose. Its Phase 3 program is named TRIUMPH, structured similarly to SURMOUNT: TRIUMPH-1 covers obesity without type 2 diabetes, TRIUMPH-2 covers obesity with type 2 diabetes, TRIUMPH-3 covers obesity with established cardiovascular disease, and TRIUMPH-4 covers obesity with obstructive sleep apnea. TRIUMPH-4 reported 28.7% weight loss at 68 weeks — the strongest result of any trial referenced on this page. Retatrutide remains investigational and has not been approved by the FDA or any other regulator.
Semaglutide vs Tirzepatide vs Retatrutide questions
Does KYIN Peptides sell semaglutide or tirzepatide?
No. KYIN Peptides supplies Retatrutide for laboratory research use only. Semaglutide and Tirzepatide are patented, FDA-approved prescription pharmaceutical products, marketed as Ozempic/Wegovy and Mounjaro/Zepbound respectively, and are not part of our catalogue. This page compares the three compounds for educational and research context only.
Is Retatrutide more effective than semaglutide or tirzepatide?
Retatrutide has shown the greatest weight reduction in trials so far — up to 28.7% in its Phase 3 TRIUMPH-4 trial, compared with tirzepatide's 20.9% (SURMOUNT-1) and semaglutide's 14.9% (STEP-1). However, retatrutide is still in Phase 3 trials and has not been approved by the FDA or any other regulator, so these results should be read as investigational rather than a confirmed real-world outcome.
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