Peptide library · Weight & metabolism
Retatrutide
Eli Lilly · investigational
Phase 328.3%average weight loss over 80 weeks in TRIUMPH-1 (2,339 adults), the highest of any obesity drug so far
What it is
A triple agonist: one molecule that activates GIP, GLP-1 and glucagon receptors.
Why researchers are interested
- 30.3% average weight loss at two years in the TRIUMPH-1 extension.
- 45% of people on the top dose lost at least 30% of their body weight.
- Knee arthritis trial: up to 28.7% weight loss and meaningful knee pain improvement.
- Type 2 diabetes trial: A1c fell 1.6 points.
Good to know
- Investigational. Lilly plans to file with FDA in early 2027.
- Results are company toplines; full peer reviewed papers are still coming.
- Stomach side effects were common, and some people reported skin sensitivity.
Evidence level: 4 of 5
Sources
Eli Lilly TRIUMPH-1 to 4 toplines (2026); AJMC, May 2026; Healio, Jan 2026
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Educational content only. Not medical advice. Last reviewed 2026-10-17.