Comparison · Updated
Tirzepatide VS Retatrutide
Short answer
Tirzepatide has stronger published evidence than Retatrutide: tier S (Approved) vs tier A (Controlled human trials).
Tirzepatide is FDA-approved (Mounjaro, Zepbound, 2022); Retatrutide is not FDA-approved.
Tirzepatide is not on the WADA Prohibited List; Retatrutide is prohibited in sport by WADA under section S0.
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Side by side
| Field | Tirzepatide | Retatrutide |
|---|---|---|
| Evidence tier | S Tier S · Approved | A Tier A · Controlled human trials |
| Tier rationale | Phase 3 RCT programmes (SURPASS, SURMOUNT); FDA-approved in 2022 for type 2 diabetes (Mounjaro) and in 2023 for weight management (Zepbound). | Phase 2 RCTs (NEJM 2023, Lancet 2023) and phase 3 RCTs (TRIUMPH-1, NEJM 2026; TRIUMPH-2/-3/-4); not approved by any regulator as of November 2026. |
| FDA status | Approved (2022) Mounjaro, ZepboundApproved for type 2 diabetes (Mounjaro, 2022) and chronic weight management (Zepbound, 2023). | Not approvedInvestigational; Lilly has said it plans to submit a US Biologics License Application in Q1 2027. |
| Other approvals | None listed | None listed |
| WADA | Not on the Prohibited List | Prohibited · S0Non-approved substances |
| Family | Metabolic | Metabolic |
| Residues | 39amino acids | 39amino acids |
| Molecular weight | 4,813.5 Da | 4,731.3 Da |
| Formula | C225H348N48O68 | C221H342N46O68 |
| Discovered | 2018Discovery and first clinical data published by Eli Lilly as LY3298176 (Coskun et al., Mol Metab 2018). | 2022Discovery and early clinical data published by Eli Lilly as LY3437943 (Coskun et al., Cell Metab 2022). |
| Routes studied | Subcutaneous | Subcutaneous |
| Mechanism | Tirzepatide is a dual GIP/GLP-1 receptor agonist built on a 39-amino-acid peptide backbone with a C20 fatty diacid moiety enabling albumin binding and once-weekly dosing. It enhances glucose-dependent insulin secretion, suppresses glucagon, slows gastric emptying, and acts on hypothalamic appetite centers to reduce food intake. | Retatrutide is a triple incretin receptor agonist that simultaneously activates GIP, GLP-1, and glucagon receptors. GLP-1 and GIP receptor activation reduces appetite and improves insulin secretion, while glucagon receptor agonism increases energy expenditure and hepatic fatty acid oxidation, producing additive weight loss effects. |
| Safety notes | FDA-approved with extensive Phase III safety data (SURPASS and SURMOUNT programs). | Gastrointestinal events (nausea, diarrhea, vomiting) were the most common adverse events in phase 2 and phase 3 trials and were dose-related. |
| Cited studies | 3 studies | 2 studies |
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Questions
- Which has stronger evidence, Tirzepatide or Retatrutide?
- Tirzepatide has stronger published evidence than Retatrutide: tier S (Approved) vs tier A (Controlled human trials). Tirzepatide: Phase 3 RCT programmes (SURPASS, SURMOUNT); FDA-approved in 2022 for type 2 diabetes (Mounjaro) and in 2023 for weight management (Zepbound). Retatrutide: Phase 2 RCTs (NEJM 2023, Lancet 2023) and phase 3 RCTs (TRIUMPH-1, NEJM 2026; TRIUMPH-2/-3/-4); not approved by any regulator as of November 2026. Tiers rate the strength of published evidence, not effectiveness.
- Is Tirzepatide FDA-approved?
- Tirzepatide is FDA-approved (Mounjaro, Zepbound, 2022). Approved for type 2 diabetes (Mounjaro, 2022) and chronic weight management (Zepbound, 2023).
- Is Retatrutide FDA-approved?
- Retatrutide is not FDA-approved. Investigational; Lilly has said it plans to submit a US Biologics License Application in Q1 2027.
- Are Tirzepatide and Retatrutide banned in sport?
- Tirzepatide is not on the WADA Prohibited List; Retatrutide is prohibited in sport by WADA under section S0.
- How do Tirzepatide and Retatrutide work?
- Tirzepatide is a dual GIP/GLP-1 receptor agonist built on a 39-amino-acid peptide backbone with a C20 fatty diacid moiety enabling albumin binding and once-weekly dosing. Retatrutide is a triple incretin receptor agonist that simultaneously activates GIP, GLP-1, and glucagon receptors.