Retatrutide
Triple Incretin Receptor AgonistinvestigationalAlso known as: LY3437943, GGG Triple Agonist
An investigational triple-agonist peptide targeting GLP-1, GIP, and glucagon receptors, producing unprecedented weight loss of up to 24% in clinical trials.
Overview
Retatrutide is a novel investigational peptide developed by Eli Lilly that simultaneously activates three incretin-related receptors: GLP-1, GIP (glucose-dependent insulinotropic polypeptide), and glucagon receptors. This triple-agonist approach represents the next frontier beyond dual agonists like tirzepatide. In Phase 2 trials, retatrutide produced remarkable weight loss of up to 24.2% at 48 weeks — the highest reported for any anti-obesity medication to date. The glucagon receptor component adds direct hepatic fat reduction and increased energy expenditure beyond what GLP-1/GIP dual agonism achieves. Retatrutide is currently in Phase 3 clinical trials for obesity and type 2 diabetes, with potential approval expected around 2026-2027.
Mechanism of Action
Retatrutide is a single molecule that activates three distinct receptors: (1) GLP-1 receptor — promotes insulin secretion, suppresses appetite, and slows gastric emptying; (2) GIP receptor — enhances insulin secretion, improves fat metabolism, and may have central weight-regulatory effects; (3) Glucagon receptor — increases hepatic glucose output (counterbalanced by GLP-1/GIP insulin effects), stimulates energy expenditure, promotes lipolysis, and reduces hepatic fat. The glucagon component uniquely drives thermogenesis and liver fat reduction, explaining the superior weight loss compared to dual agonists.
Molecular Formula
Investigational (not fully disclosed)
Molecular Weight
~4500 g/mol (estimated)
Sequence
Modified peptide with GLP-1, GIP, and glucagon receptor binding domains (proprietary)
Dosage Protocols
Dose Range
1mg – 12mg
Frequency
Once weekly
Route
subcutaneous
Cycle Length
48 weeks (trial duration)
Phase 2 trial used dose escalation to 1mg, 4mg, 8mg, or 12mg weekly. The 12mg group achieved 24.2% weight loss. Gradual titration required to manage GI side effects.
Source: Phase 2 clinical trial (Jastreboff et al., NEJM 2023)
🧮 Personalized Dosage Calculator
💰 Estimated Pricing
Typical Supply
Multi-dose vial or pen
Last Updated
2026-02
Triple agonist (GLP-1/GIP/glucagon) by Eli Lilly. Phase 3 trials. Compounded versions emerging. Strongest weight loss results in trials (~24%).
⚠️ Prices are estimates based on publicly available data and may vary significantly by vendor, location, and prescription status. This is not medical or financial advice.
Side Effects
| Effect | Severity |
|---|---|
| Nausea | moderate |
| Diarrhea | mild |
| Vomiting | moderate |
| Constipation | mild |
| Decreased appetite | mild |
| Increased heart rate | mild |
Pros & Cons
Produces the highest weight loss of any anti-obesity drug tested to date (up to 24.2% at 48 weeks)
Triple receptor agonism provides unique benefits including direct liver fat reduction via glucagon signaling
Convenient once-weekly injection
Strong HbA1c reductions for diabetes management alongside weight loss
Still investigational — not yet approved, Phase 3 trials ongoing
High rates of GI side effects typical of the incretin class
Long-term safety data not yet available
Glucagon receptor activation theoretically risks hyperglycemia, though balanced by GLP-1/GIP effects in trials
Research Studies
🩸 Blood Work
HbA1c
Triple agonist (GLP-1/GIP/Glucagon) — blood sugar essential
Fasting Blood Glucose
Glucagon component may affect glucose differently
Lipid Panel
Glucagon component significantly affects lipid metabolism
Kidney Function (BMP/CMP)
Monitor renal function
Thyroid Panel (TSH, T3, T4)
GLP-1 component carries thyroid warnings
Liver Function Panel (AST/ALT)
Glucagon receptor activation affects hepatic metabolism
Investigational triple agonist (GLP-1/GIP/Glucagon). More comprehensive monitoring recommended due to novel mechanism. Not yet FDA-approved.
Legal Status
Investigational — not yet approved by any regulatory agency. Currently in Phase 3 clinical trials (Eli Lilly). Not available for prescription or research purchase.
💬 Community Experiences
Share Your ExperienceThe triple agonist approach is next level. Lost 28 lbs in 3 months with better appetite control than semaglutide alone. GIP + GLP-1 + glucagon receptor activation is the future.
Early adopter here. Weight loss is impressive — about 4 lbs per week initially. Some GI sides but less than expected. Monitoring liver enzymes as recommended. Very promising.
Using research-grade. Metabolic markers improving rapidly — triglycerides dropped 40%, fasting glucose down 15 points. The glucagon component adds a unique thermogenic effect.
⚠️ Individual experiences may vary. These are user-submitted reports for informational purposes only. Always consult a healthcare professional before starting any peptide protocol.
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