Eli Lilly's investigational triple agonist of the GLP-1, GIP and glucagon receptors. The glucagon-receptor activity is intended to add energy-expenditure increase to GLP-1-mediated appetite suppression.

How does Retatrutide compare to Tirzepatide?

Phase 2 results showed roughly −24% weight loss vs Tirzepatide's SURMOUNT-1 result of −20.9%. The two-vs-three-receptor distinction is plausible mechanism but the comparison is across separate trials, not head-to-head.

When will Retatrutide be available?

Authorisation depends on Phase 3 read-outs (TRIUMPH programme) from 2026 onward, plus regulatory review. Earliest realistic market entry is late this decade.

Retatrutide — Peptidepedia

MOLECULAR INFORMATION

Molecular information

Type: Triple GLP-1 / GIP / glucagon receptor agonist · weekly subcutaneous · investigational

Retatrutide is Eli Lilly’s investigational triple agonist of the GLP-1, GIP and glucagon receptors. The addition of glucagon-receptor activity is intended to combine appetite suppression with increased energy expenditure. Phase 2 data showed ~24% mean weight loss at 48 weeks — the largest published for any metabolic peptide to date.

Status

Phase 3 (TRIUMPH programme) ongoing for obesity and type 2 diabetes
No regulatory authorisation; investigational use only

Why we grade it B

One adequately-powered Phase 2 RCT with a striking effect size, but no independent replication and no completed Phase 3. The mechanism is plausible and consistent with the tirzepatide arc. Promotion to A waits on Phase 3 read-outs.

References

Phase 2 obesity 2023

338 participants

~24% mean weight loss at 48 weeks at highest dose — largest published effect size for any metabolic peptide to date
TRIUMPH programme 2024

Phase 3 in obesity and T2DM — multiple sub-trials underway, read-outs from 2026 onward

Frequently asked questions

What is Retatrutide?: Eli Lilly's investigational triple agonist of the GLP-1, GIP and glucagon receptors. The glucagon-receptor activity is intended to add energy-expenditure increase to GLP-1-mediated appetite suppression.
How does Retatrutide compare to Tirzepatide?: Phase 2 results showed roughly −24% weight loss vs Tirzepatide's SURMOUNT-1 result of −20.9%. The two-vs-three-receptor distinction is plausible mechanism but the comparison is across separate trials, not head-to-head.
When will Retatrutide be available?: Authorisation depends on Phase 3 read-outs (TRIUMPH programme) from 2026 onward, plus regulatory review. Earliest realistic market entry is late this decade.