Retatrutide's triple GLP-1/GIP/glucagon agonism produces ~24.2% weight loss in Phase 2 vs semaglutide's ~15% in Phase 3 — the largest gap in the GLP class. Critical caveat: retatrutide's data is Phase 2 only; Phase 3 TRIUMPH results are pending.
Retatrutide's ~24.2% weight loss figure comes from a Phase 2 trial (n=338, 48 weeks). Semaglutide's ~15% comes from a Phase 3 trial (n=1,961, 68 weeks). Phase 2 trials enroll smaller, more selected populations and typically show higher efficacy than Phase 3. The TRIUMPH Phase 3 program is ongoing — final weight loss figures may differ from Phase 2 data.
| Timepoint | Semaglutide | Retatrutide |
|---|---|---|
| Week 4 | ~2–3% | ~2–4% |
| Week 12 | ~5–7% | ~7–10% |
| Week 24 | ~9–11% | ~14–17% |
| Week 36 | ~12–14% | ~19–22% |
| Week 48 | ~13–14% | ~24.2% (Phase 2 endpoint) |
| Week 68 | ~15% (STEP-1 endpoint) | Phase 3 data pending |
| Parameter | Semaglutide | Retatrutide |
|---|---|---|
| Receptor mechanism | GLP-1 mono-agonist | GLP-1 + GIP + Glucagon (triple) |
| Average weight loss (max dose) | ~15% (2.4 mg, STEP-1, Ph3) | ~24.2% (12 mg, Phase 2) |
| Average weight loss (mid dose) | ~10–14% (1–2 mg, Ozempic) | ~17.3% (4 mg, Phase 2) |
| Data phase | Phase 3 (STEP program) | Phase 2 only (TRIUMPH ongoing) |
| Trial duration | 68 weeks (STEP-1) | 48 weeks (Phase 2) |
| FDA approval status | Approved (Ozempic/Wegovy) | Not approved (est. 2027–2028) |
| Nausea rate (therapeutic dose) | 30–44% | ~47–58% (Phase 2) |
| GI discontinuation rate | ~5–8% | Phase 2 data pending Ph3 |
| Half-life | ~7 days (weekly injection) | ~6 days (weekly injection) |
| Cardiovascular outcome data | SELECT trial (20% CV risk ↓) | No CV outcome data yet |
| Long-term safety data | 5+ years real-world data | Phase 2 only (limited) |
| Research-grade availability | Available (Purgo Labs) | Available (Purgo Labs) |
Yes — retatrutide produced ~24.2% mean weight loss at 48 weeks in Phase 2 trials (12 mg dose), compared to semaglutide 2.4 mg (Wegovy) ~15% at 68 weeks in STEP-1. However, this is a critical caveat: retatrutide's data is from Phase 2, while semaglutide's is from Phase 3. Phase 2 trials typically enroll more homogeneous populations and may not reflect real-world Phase 3 results. Retatrutide Phase 3 (TRIUMPH program) is ongoing with results expected 2025–2026.
In available clinical data, retatrutide 12 mg produces approximately 9–10 percentage points more weight loss than semaglutide 2.4 mg: ~24.2% vs ~15%. For a 100 kg person, that translates to ~24 kg vs ~15 kg lost. The gap is the largest in the current GLP class. However, Phase 3 results may narrow this gap as retatrutide is tested in broader, more heterogeneous populations.
Retatrutide is a triple agonist activating GLP-1, GIP, and glucagon receptors simultaneously. Semaglutide activates only the GLP-1 receptor. The addition of glucagon receptor agonism is the key differentiator: glucagon increases energy expenditure (thermogenesis), promotes fat oxidation, and reduces hepatic fat. This third mechanism adds to the appetite suppression and insulin effects of GLP-1/GIP dual agonism, producing the largest weight loss seen in the GLP class to date.
Retatrutide's ~24.2% weight loss figure comes from a Phase 2 trial (n=338, 48 weeks). Semaglutide's ~15% comes from STEP-1, a Phase 3 trial (n=1,961, 68 weeks). Phase 2 trials are smaller, shorter, and enroll more selected populations — they often show higher efficacy than Phase 3 results in broader populations. Retatrutide's Phase 3 TRIUMPH program (TRIUMPH-1 through TRIUMPH-4) is ongoing. The Phase 3 weight loss figure may be lower than 24.2% when results are published.
No. As of April 2026, retatrutide is not FDA approved. Phase 3 TRIUMPH trials are ongoing with primary completion expected 2025–2026. An NDA submission is estimated for 2026–2027, with potential FDA approval in 2027–2028. Semaglutide (Ozempic/Wegovy) is FDA approved for T2D (2017) and obesity (2021).
Semaglutide has a nausea rate of ~30–44% at therapeutic doses. Retatrutide showed ~47–58% nausea in Phase 2 at the 12 mg dose — higher than semaglutide, likely due to the addition of glucagon receptor agonism which has independent GI effects. The Phase 3 TRIUMPH program will provide more definitive nausea data across larger populations.
Yes. Research-grade semaglutide is available from verified suppliers like Purgo Labs for in vitro and preclinical research purposes. This is distinct from FDA-approved Ozempic, Wegovy, and Rybelsus, which require a prescription. Purgo Labs' research-grade semaglutide comes with third-party COAs from accredited US labs confirming ≥99% purity.
Purgo Labs provides pharmaceutical-grade semaglutide and retatrutide with third-party COAs confirming ≥99% purity. Use code HEALTH for 15% off.
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