Retatrutide
An investigational triple agonist (GIP, GLP-1 and glucagon receptors) in clinical trials for obesity and type 2 diabetes. Early human data look striking, but it is not approved.
Quick take
- What it is: an investigational peptide that activates three receptors at once: GIP, GLP-1 and glucagon.
- What it is being studied for: obesity and type 2 diabetes.
- What we actually know: early- and mid-stage human trials report large weight reductions, but pivotal results and approval are still pending.
- Status: investigational — in clinical trials, not approved by the FDA for any use.
What it is
Retatrutide is an investigational triple receptor agonist — a peptide engineered to activate three receptors at once: GIP, GLP-1 and glucagon. It is sometimes called a “triple agonist” or “triple G.” It is being studied for obesity and type 2 diabetes and is not approved by the FDA for any use.1
It builds conceptually on GLP-1 drugs (one receptor) and dual GIP/GLP-1 agonists like tirzepatide (two receptors), adding glucagon-receptor activity.
How it works
GLP-1 and GIP are incretin hormones that influence insulin, appetite and gastric emptying. Glucagon acts on the liver and on energy metabolism and may increase energy expenditure. Retatrutide is designed to combine all three signals in a single molecule, with the theory that adding glucagon activity could enhance fat loss beyond what incretin action alone achieves.1,2 Whether this mechanism translates into a durable net benefit, and at what safety cost, is still being established in trials.
What the evidence shows
Animal studies
Preclinical work on multi-receptor agonists suggested that adding glucagon-receptor activity to incretin signaling could increase energy expenditure and weight loss, supporting progression to human studies.2
Human studies
Early- and mid-stage human trials of retatrutide have reported large reductions in body weight over the study periods, among the most pronounced reported for this drug class.3 These results are encouraging but preliminary: they come from earlier-phase trials, and pivotal long-term outcome data are still pending. Until those complete, conclusions about durable benefit and safety remain provisional.
Dosages reported in the literature
Informational only. Retatrutide is an investigational drug. The figures below describe doses used in studies; they are not a recommendation or a prescription. This compound is not approved and should only be received within a regulated clinical trial.
| Setting | Route | Reported range |
|---|---|---|
| Clinical trials (titrated) | Subcutaneous, weekly | Escalating doses studied across a range; set by trial protocol |
Because retatrutide is investigational, no dose here should be read as established as safe or effective for general use.
Safety & side effects
In trials, the most commonly reported side effects have been gastrointestinal — nausea, vomiting and diarrhea — typical of this drug class, often dose-related. Effects related to glucagon activity (for example on heart rate) are also under study.3 Because there are no long-term, real-world safety data yet, the full risk profile is genuinely unknown.
A practical concern in the unregulated market is product quality. “Research” retatrutide sold outside of clinical trials does not carry the quality, purity or dose assurances of an approved medicine.
Legal & regulatory status
Retatrutide is not approved by the FDA for any use. It is investigational and being evaluated in clinical trials. Marketing or selling it as a finished drug product would fall outside its regulatory status. Rules differ by country and change over time.1
References
- Coskun T, Urva S, Roell WC, et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: from discovery to clinical proof of concept. Cell Metabolism. 2022;34(9):1234-1247.e9. [PMID 35985340, doi:10.1016/j.cmet.2022.07.013]
- Coskun T, Urva S, Roell WC, et al. LY3437943, a novel triple glucagon, GIP, and GLP-1 receptor agonist for glycemic control and weight loss: from discovery to clinical proof of concept. Cell Metabolism. 2022;34(9):1234-1247.e9. [PMID 35985340, doi:10.1016/j.cmet.2022.07.013]
- Jastreboff AM, Kaplan LM, Frias JP, et al. Triple-Hormone-Receptor Agonist Retatrutide for Obesity — A Phase 2 Trial. New England Journal of Medicine. 2023;389(6):514-526. [PMID 37366315, doi:10.1056/NEJMoa2301972]