Semaglutide vs Tirzepatide vs Retatrutide — GLP-1 Comparison
Three generations of GLP-1 metabolic peptides — each adding another receptor to the mix. Semaglutide targets one receptor, Tirzepatide two, and Retatrutide three. Each generation has shown greater average weight loss than the last. Here's how they compare based on clinical trial data.
| Semaglutide | Tirzepatide | Retatrutide | |
|---|---|---|---|
| Generation | 1st | 2nd | 3rd (investigational) |
| Receptors Targeted | GLP-1 only | GLP-1 + GIP | GLP-1 + GIP + Glucagon |
| Nickname | GLP-1 agonist | Dual agonist | Triple agonist / “Triple G” |
| Brand Names | Ozempic, Wegovy, Rybelsus | Mounjaro, Zepbound | None yet — not FDA approved |
| FDA Status | Approved (diabetes 2017, obesity 2021) | Approved (diabetes 2022, obesity 2023) | Phase 3 trials (TRIUMPH program) — approval expected 2027–2028 |
| Average Weight Loss | ~14.9% over 68 weeks (STEP 1 trial) | ~22.5% over 72 weeks (SURMOUNT-1) | ~24.2% at 12mg dose (Phase 2/3 data) |
| Blood Sugar Control | Reduces HbA1c ~1–2% | Reduces HbA1c ~2–2.5% | Early data shows superior glucose control |
| Liver Fat Reduction | Moderate | Significant | Up to 86% reduction (Phase 3 TRIUMPH-4 data) |
| GI Side Effects | Nausea, vomiting, diarrhea — common | Similar — possibly slightly more at high doses | Similar profile — still being characterized |
| Dosing | Once weekly injection (or daily oral) | Once weekly injection | Once weekly injection (expected) |
| Availability | Widely available globally | Widely available globally | Clinical trials only — not commercially available |
| Key Trial | STEP 1 (NEJM 2021) | SURMOUNT-1, SURPASS-2 | TRIUMPH program Phase 3 |
Bottom Line
Each generation shows greater efficacy than the last — but more receptors means more unknowns. Semaglutide has the longest safety record and broadest availability. Tirzepatide has now beaten semaglutide head-to-head in the SURMOUNT-5 trial. Retatrutide shows the most dramatic weight loss data of all three, but is not yet FDA approved and long-term safety data is still accumulating.
Note: All three are prescription medications. Retatrutide is currently only available through clinical trials.
For educational and research purposes only. Not medical advice.