Retatrutide: Research Overview, Mechanisms, and Current Evidence
Retatrutide (LY3437943) is an investigational triple agonist that activates the glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), and glucagon receptors. In Phase 2 trials it produced large reductions in body weight and liver fat. It is a clinical-stage drug that is not approved by any regulatory agency and remains under investigation. Because it is a clinical-stage drug, the framing here is research-use only. The information below summarizes published research for educational and research purposes only. It is not medical advice and is not guidance for use in humans.
Retatrutide is an investigational, clinical-stage drug. Available for research use from our preferred vendor, Project Zero. For laboratory research use only.
How It Works (Preclinical Mechanisms)
Retatrutide acts on three metabolic hormone receptors at once, an approach reported to combine appetite, glucose, and energy-expenditure effects.
- Activates GIP, GLP-1, and glucagon receptors in a single molecule.
- The GLP-1 and GIP activity is reported to reduce appetite and improve glucose handling.
- The glucagon component is reported to increase energy expenditure, which may add to weight loss.
- Studied for large reductions in body weight and liver fat in Phase 2 trials.
Areas of Research Interest
Published studies have examined retatrutide in early-phase trials of obesity and related metabolic conditions.
Obesity
Studied in a Phase 2 trial reporting weight reductions that approached those seen with bariatric surgery.
Liver fat (MASLD)
Investigated in a Phase 2a substudy for reducing liver fat in metabolic dysfunction-associated steatotic liver disease.
Cardiometabolic comorbidities
Examined for effects on metabolic measures linked to insulin sensitivity and lipid metabolism.
Multi-agonist pharmacology
Studied as an example of engineering one peptide to act on several metabolic receptors.
Reported Study Parameters
For laboratory research use only. The table below reports the doses and routes used in published clinical trials, with sources. It describes what was administered in those studies and is not a protocol, recommendation, or guidance for use in humans or animals. Because retatrutide is an investigational, clinical-stage drug, this information is provided for research context only.
| Research Model | Dose and Route Reported | Source |
|---|---|---|
| Adults with obesity (Phase 2 RCT) | Once-weekly subcutaneous retatrutide 1, 4, 8, or 12 mg for 48 weeks (with lower starting doses) | Jastreboff 2023·DOI |
| MASLD (liver fat) substudy (Phase 2a RCT) | Once-weekly subcutaneous retatrutide 1, 4, 8, or 12 mg for 48 weeks | Sanyal 2024·DOI |
| Human research (regulatory status) | Investigational triple agonist in clinical development; not approved by any regulatory agency; provided here for research use only | Ganamurali 2026·DOI |
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Latest Research (2023 to 2026)
Recent peer-reviewed literature indexed on PubMed reports striking early-phase results for retatrutide alongside reminders that it remains investigational.
Phase 2 obesity trial
A 2023 Phase 2 trial in 338 adults with obesity reported mean weight reductions at 48 weeks of up to 24.2% with retatrutide 12 mg once weekly, versus 2.1% with placebo, with dose-related, mostly mild to moderate gastrointestinal side effects. PubMed·DOI
Liver fat in MASLD (Phase 2a)
A 2024 substudy reported that retatrutide reduced liver fat by up to 82.4% at 24 weeks in participants with metabolic dysfunction-associated steatotic liver disease, with most participants in the higher-dose groups reaching normal liver fat. PubMed·DOI
Triple-agonist pharmacology (review)
A 2026 review described retatrutide as a triple agonist representing a potential paradigm shift in obesity pharmacotherapy, while emphasizing that the evidence is from Phase 2 trials and that it remains in development. PubMed·DOI
Research Questions
What is retatrutide?
Retatrutide is an investigational triple agonist that activates GIP, GLP-1, and glucagon receptors. It is studied for obesity and related metabolic conditions and is not an approved drug.
What is the current state of human evidence?
Phase 2 trials report large reductions in body weight and liver fat. Phase 3 development is ongoing, and no regulatory agency has approved retatrutide.
What does the available safety literature suggest?
Phase 2 trials reported dose-related, mostly mild to moderate gastrointestinal side effects and transient increases in heart rate. Long-term safety has not been established, and the drug remains experimental.
Referenced Citations
Literature indexed on PubMed.
- Jastreboff, A.M., et al. (2023). Triple-hormone-receptor agonist retatrutide for obesity: a phase 2 trial. N. Engl. J. Med., 389(6), 514-526. PubMed·DOI
- Sanyal, A.J., et al. (2024). Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial. Nat. Med., 30(7), 2037-2048. PubMed·DOI
- Ganamurali, N., & Sabarathinam, S. (2026). The triple-agonist revolution: retatrutide and the paradigm shift in multi-hormonal pharmacotherapy for obesity and cardiometabolic comorbidities. Clin. Pharmacol. Drug Dev., 15(1), e70001. PubMed·DOI
PeptideInfo.org provides information strictly for educational and research purposes. All referenced products are intended for laboratory and research use only and are not approved for human consumption, medical use, or self-administration. Nothing on this page constitutes medical advice. Research summaries reference literature indexed on PubMed.