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No. 021 · Metabolic · Weight Loss Peptide

Retatrutide

LY3437943

A Tier A · Controlled human trials how tiers work →
  • Not FDA approved
  • WADA ✗ S0
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Fingerprint 39 residues
Retatrutide sequence fingerprint
  • Nonpolar 18
  • Polar 12
  • Positive charge 2
  • Negative charge 4
  • Modified / non-standard 3

Each dot is a residue placed around the ring from N- to C-terminus; its distance from the centre reflects its chemistry.

01

Quick answers

What is Retatrutide?
An investigational triple agonist of the GIP, GLP-1, and glucagon receptors developed by Eli Lilly.
How strong is the evidence for Retatrutide?
Tier A (controlled human trials) on the peptidemeta evidence scale. 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.
Is Retatrutide FDA-approved?
No. Retatrutide is not approved by the FDA for any use. Investigational; Lilly has said it plans to submit a US Biologics License Application in Q1 2027.
Is Retatrutide banned in sport?
Yes. Retatrutide is prohibited in sport by the World Anti-Doping Agency under S0 (non-approved substances).
How does Retatrutide work?
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.
What is known about the safety of Retatrutide?
Gastrointestinal events (nausea, diarrhea, vomiting) were the most common adverse events in phase 2 and phase 3 trials and were dose-related. Not FDA-approved.

Last reviewed · editorial policy · markdown

02

Evidence

  1. D In vitro
  2. C Animal
  3. B Human pilot
  4. A RCT
  5. S Approved

TIER A — At least one published randomized controlled trial in humans.

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, safety, or a recommendation.

03

At a glance

Residues
39 amino acids, N→C
Molecular weight
4,731.3 Da
Formula
C221H342N46O68
Discovered
2022 Discovery and early clinical data published by Eli Lilly as LY3437943 (Coskun et al., Cell Metab 2022).
Routes studied
Subcutaneous Routes used in published research
FDA
Not approved Investigational; Lilly has said it plans to submit a US Biologics License Application in Q1 2027.
WADA
Prohibited · S0 Non-approved substances
04

Sequence

N → C · 39 residues · hover, tap, or use arrow keys to inspect

Note K17 carries a C-20 fatty diacid attached via a γ-Glu–AEEA linker; [αMeLeu] = α-methyl-L-leucine.

05

Overview

An investigational triple agonist of the GIP, GLP-1, and glucagon receptors developed by Eli Lilly. In the phase 3 TRIUMPH-1 trial, adults with obesity lost 17.6-25.0% of body weight over 80 weeks versus 3.9% with placebo.

Research status Phase 3 RCTs reported (TRIUMPH-1, NEJM 2026); not approved by any regulator as of November 2026, with a US application planned for 2027

06

Mechanism

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.

07

Effects reported in research

Reported outcomes, not promises. Some come from controlled human trials; others may be from smaller or preclinical studies — check the studies below.

  • Significant body weight reduction
  • Improved glycemic control
  • Reduced appetite and caloric intake
  • Favorable lipid profile changes
08

Safety & unknowns

Gastrointestinal events (nausea, diarrhea, vomiting) were the most common adverse events in phase 2 and phase 3 trials and were dose-related. Not FDA-approved. Monitor for potential thyroid C-cell signals as with other incretin agonists.

Unknowns. Trial safety data apply to the populations, formulations and conditions studied.

Informational only — not medical advice. peptidemeta publishes no dosing, protocols, or sourcing. Talk to a qualified clinician about any treatment decision.

09

Studies [2]

  1. Clinical trial 2026

    Retatrutide, a Triple Hormone Receptor Agonist, for Treatment of Obesity

    Jastreboff AM, Kaplan LM, Davies MJ, et al. New England Journal of Medicine

    In the 80-week phase 3 TRIUMPH-1 RCT in 2339 adults with obesity without diabetes, mean weight change was -17.6% to -25.0% across doses versus -3.9% with placebo; gastrointestinal events were most common.

    [pubmed] [doi]

  2. Clinical trial 2023

    Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial

    Jastreboff AM, Kaplan LM, Frías JP, et al. New England Journal of Medicine

    In this 48-week phase 2 RCT in 338 adults with obesity, mean weight change ranged from -8.7% (1 mg) to -24.2% (12 mg) versus -2.1% with placebo.

    [pubmed] [doi]

11

Status sources

Sources behind the tier, regulatory status, sequence and dates on this page.

12

Cite this entry

$ cite --format=apa

peptidemeta. (2026). Retatrutide. In peptidemeta: The peptide library, ranked by evidence. Retrieved November 8, 2026, from https://peptidemeta.com/p/retatrutide/

$ cite --format=bibtex 
@misc{peptidemeta-retatrutide,
  title = {Retatrutide},
  author = {{peptidemeta}},
  year = {2026},
  howpublished = {\url{https://peptidemeta.com/p/retatrutide/}},
  note = {Accessed 2026-11-08}
}

Accessed date reflects when you opened this page. Cite primary studies for scientific claims.

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