Retatrutide
ClinicalAlso known as LY3437943
GIP / GLP-1 / glucagon triple agonist
The triple agonist posting the biggest weight-loss numbers yet.
- References
- 3
- Human-grade claims
- 1 of 2
- Evidence floor
- Clinical
- Status
- Research-only
An investigational once-weekly peptide that activates three metabolic receptors at once. Phase 2 data are striking, but it is not yet approved — this is late-stage clinical promise, not a settled therapy.
How it works
Retatrutide adds glucagon-receptor activity to the GIP + GLP-1 combination. The glucagon arm is thought to raise energy expenditure on top of the appetite and insulin effects of the other two — a three-receptor bet on bigger metabolic swings.
What it's studied for
- [1] Jastreboff et al., 2023 (NEJM, Phase 2)
83% of participants lost ≥15% body weight and mean loss reached ~24.2% at 48 weeks on the top dose in a Phase 2 RCT.
Clinical - [2] Structural insights into retatrutide (PMC)
Triple agonism at the GLP-1, GIP, and glucagon receptors distinguishes it mechanistically from dual agonists.
Preclinical
Safety & limitations
In the Phase 2 trial, adverse events were mostly gastrointestinal and dose-related. The glucagon-receptor activity draws attention to heart rate and glucose, which the Phase 3 program was designed to characterize.
[1] Jastreboff et al., 2023 (NEJM, Phase 2)Regulatory & legal status
Not approved anywhere as of 2026. The Phase 3 TRIUMPH program is complete, and Eli Lilly has said it plans to file for approval in Q1 2027.
[3] ClinicalTrials.gov — TRIUMPH-1 (NCT05929066)Frequently asked
- Can I get retatrutide?
- Not as an approved medicine — it remains investigational. Any material sold as retatrutide outside a clinical trial is unapproved and unverified.
References
Written by Twenty Residues editorial. Reviewed by Pending named medical review.
Last updated September 19, 2026.
Update history
- 2026-09-19 — Sourced review — every claim checked against primary literature; sequence, regulatory status, safety, and FAQs added.