Retatrutide
Triple GIP/GLP-1/Glucagon Receptor Agonist (LY3437943)
Mechanism of Action
Triple agonist of the glucose-dependent insulinotropic polypeptide (GIP), GLP-1, and glucagon receptors. GIP/GLP-1 co-agonism suppresses appetite and improves insulin secretion; glucagon receptor agonism adds increased energy expenditure and lipolysis on top of the incretin effects, driving weight loss beyond dual agonists like tirzepatide.
Key Benefits
- Largest weight loss of any incretin-class peptide studied to date (~17–24% at 48 weeks by dose, phase 2)
- Dose-dependent, near-universal achievement of 5%+ weight loss at higher doses
- Improved glycemic parameters alongside weight loss
- Glucagon co-agonism may better preserve energy expenditure than GLP-1/GIP dual agonists
Dosing Protocol
A lower starting dose (2 mg vs 4 mg) mitigated GI side effects during titration in phase 2 data. Still investigational — not an approved or compoundable product. Note: PubMed has zero hits for "RTA" combined with retatrutide or its dev code LY3437943 — the compound itself is unambiguous, but "RTA" as vendor shorthand is unverified. Listed here under its real name.
Ideal Candidates
Adults with obesity interested in the most aggressive incretin-class weight-loss data available; appropriate only in a research context — not yet an approved therapy.
Side Effects & Safety
Dose-related GI events (nausea, vomiting, diarrhea), mostly mild-to-moderate; dose-dependent increases in heart rate that peak around 24 weeks then decline.
Regulatory Status
RestrictedInvestigational — Phase 3 (TRIUMPH program) ongoing at Eli Lilly. No FDA approval, no 503A listing. Research use only; not an approved or compoundable product.
Evidence & Citations
Frequently asked
What is Retatrutide?+
Retatrutide (Triple GIP/GLP-1/Glucagon Receptor Agonist (LY3437943)) is a peptide studied for triple receptor agonist and strongest weight loss data. Triple agonist of the glucose-dependent insulinotropic polypeptide (GIP), GLP-1, and glucagon receptors. GIP/GLP-1 co-agonism suppresses appetite and improves insulin secretion; glucagon receptor agonism adds increased energy expenditure and lipolysis on top of the incretin effects, driving weight loss beyond dual agonists like tirzepatide.
What is the dosing protocol for Retatrutide?+
Literature commonly references 2 mg/wk (low) to 8 mg/wk (maintenance) via SubQ weekly, on a ongoing cycle. Educational reference only — a licensed Stackhaus Health provider sets any personalized protocol.
What is the regulatory status of Retatrutide?+
Investigational — Phase 3 (TRIUMPH program) ongoing at Eli Lilly. No FDA approval, no 503A listing. Research use only; not an approved or compoundable product.
Where can I access Retatrutide?+
Research-grade Retatrutide is available through Stackhaus Research. For a personalized, provider-reviewed protocol, consult a licensed clinician through Stackhaus Health.
More in Weight Management
Used in these stacks
Retatrutide appears in 1 research protocol in the Stackhaus Academy library.