Peptide Encyclopedia / Retatrutide
EncyclopediaRetatrutide (LY3437943) is an Eli Lilly peptide that activates three receptors at once, GIP, GLP-1, and glucagon, and is under study for obesity and related metabolic conditions. Phase 2 trials reported strong weight loss and the Phase 3 TRIUMPH program is running, but it holds no FDA approval. Educational only, not medical advice.
| Also known as | LY3437943 |
| Class | Triple hormone-receptor agonist (GIP / GLP-1 / glucagon) |
| Developer | Eli Lilly |
| Researched for | Obesity and related metabolic conditions |
| Route | Subcutaneous, once weekly (in trials) |
| Half-life | Approximately 6 days (early-phase clinical pharmacology) |
| Regulatory status | Investigational. Phase 3 (TRIUMPH) ongoing. Not FDA-approved |
Retatrutide is a single peptide that acts on three receptors at once: GIP, GLP-1, and glucagon. The first two are the same targets behind drugs like semaglutide and tirzepatide, which reduce appetite and improve insulin response. The added glucagon-receptor activity is thought to raise energy expenditure, which is the main reason retatrutide is being watched so closely. It is developed by Eli Lilly and administered subcutaneously once a week in trials.
In a Phase 2, double-blind, randomized, placebo-controlled trial in adults with obesity (BMI 30 or higher, or 27 to under 30 with a weight-related condition), once-weekly retatrutide produced dose-dependent weight loss, among the largest reductions reported for an incretin-based agent at the highest doses studied. The specific percentages, timelines, and safety details are in the published Phase 2 results. Retatrutide has since moved into the Phase 3 TRIUMPH program. Because it is still investigational, there is no approved label and no long-term outcome data yet.
We deliberately do not print an exact "percent lost" headline number here, because single figures get quoted out of context and change between doses and trials. See the primary Phase 2 publication for the precise values.
Early-phase trials used once-weekly subcutaneous doses roughly in the 1 to 12 mg per week range, reached by gradual titration that starts low and steps up over weeks to reduce gastrointestinal side effects. This is a description of how trials were run, not an approved or recommended regimen. There is no consensus or regulatory dose because the drug is not approved.
If you are tracking a titration schedule, small dosing errors are common where people confuse syringe units with milligrams. Our dose converter makes mg, mcg, mL, and units line up, and the units vs mg explainer covers why they are not the same thing.
The side-effect profile reported in trials is consistent with the GLP-1 class: nausea, diarrhea, vomiting, and constipation, generally dose-related and most common while titrating up. Glucagon-receptor activity can also affect heart rate and other parameters, which is one reason clinical supervision matters. This is general educational information, not a complete safety profile.
If you are following a protocol under appropriate guidance, PepWise logs each weekly dose, handles the reconstitution math, tracks your titration and weight trend, and turns it into a provider PDF. See the retatrutide tracker or start free.
An Eli Lilly investigational peptide that activates three receptors (GIP, GLP-1, glucagon), in development for obesity. Not FDA-approved.
Phase 2 reported dose-dependent weight loss, among the largest for an incretin-based agent at the top doses studied. See the published Phase 2 results for exact figures.
No. It is investigational and in Phase 3 trials.
About 1 to 12 mg per week subcutaneously, reached by gradual titration. Trial doses, not an approved regimen.
PepWise is an informational and educational tracking tool, not medical advice and not a medical device. Retatrutide is investigational and not FDA-approved. Consult a licensed healthcare provider before starting, changing, or stopping any protocol. Operated by STC Consulting, Inc.
