A next-generation weight loss drug from Eli Lilly that hits three gut hormone receptors at once (GLP-1, GIP, and glucagon) -- currently in Phase 2/3 clinical trials. At low doses (2 mg), it optimizes metabolism and protects the brain WITHOUT major weight loss. At higher doses (8-12 mg), it can produce up to 24% body weight loss. The GLP-1 pathway also provides significant brain protection, with positive results seen in 175+ disease models.
What to Expect
Week 1–2
Appetite suppression with possible GI adjustment. Nausea during titration similar to GLP-1 agonists. Start low and titrate slowly over weeks.
Week 3–6
Accelerated weight loss exceeding dual-agonist compounds. Increased thermogenesis (feeling warmer). Improved energy from glucagon-mediated fat oxidation.
Week 8+
Potentially the most aggressive weight loss of any incretin agonist (20-24% body weight). Significant metabolic improvement. Hepatic fat reduction.
Common Side Effects
Scientific Overview
Retatrutide (LY3437943) is a triple agonist peptide targeting GIP, GLP-1, and glucagon receptors simultaneously. The glucagon receptor component adds thermogenic and lipolytic effects beyond dual-agonist approaches. Phase 2 data demonstrated up to 24.2% body weight reduction at 48 weeks (12mg dose), representing the most potent weight loss observed in an obesity pharmacotherapy trial. The triple agonist mechanism produces synergistic effects on energy expenditure, appetite suppression, and hepatic lipid metabolism.
Dosing
For health optimization: 2 mg per week (start at 1 mg for the first 4 weeks). For weight loss: gradually increase from 1 to 4 to 8 to 12 mg over months. Its long half-life (4-7 days) means you only inject once a week.
Practical Guide
Reconstitution
Clinical trial format — follow prescriber instructions. Compounded versions: follow pharmacy reconstitution guide.
Storage
Refrigerate. Follow prescriber/pharmacy storage guidance.
Injection Sites
Subcutaneous injection. Titrate slowly to minimize GI side effects. Follow prescriber's titration schedule.
Timing
Once weekly injection. Same day each week. Any time of day.
Food
No food timing requirement. Smaller, more frequent meals reduce nausea.
Benefit Profile
Medical Considerations
Contraindications
- ✕Personal or family history of medullary thyroid carcinoma
- ✕MEN2 syndrome
- ✕Pregnancy/nursing
- ✕History of pancreatitis
- ✕Severe gastroparesis
- ✕Uncontrolled hyperthyroidism
Drug Interactions
Recommended Monitoring
- →HbA1c every 3 months
- →Liver enzymes (ALT, AST)
- →Lipase/amylase
- →Heart rate and blood pressure
- →Thyroid function
This information is for educational purposes only. Always consult a qualified healthcare provider before starting any peptide protocol.
Published Research
Efficacy and Safety of GLP-1 Receptor Agonists, Dual Agonists, and Retatrutide for Weight Loss in Adults With Overweight or Obesity: A Bayesian NMA.
Efficacy and safety of triple hormone receptor agonist retatrutide for the management of obesity: a systematic review and meta-analysis.
Comparative Meta-Analysis of Retatrutide Versus Placebo and Dulaglutide for Weight Loss and Diabetes Management: Insights From Clinical Trials.
Effects of retatrutide on body composition in people with type 2 diabetes: a substudy of a phase 2, double-blind, parallel-group, placebo-controlled, randomised trial.
Triple hormone receptor agonist retatrutide for metabolic dysfunction-associated steatotic liver disease: a randomized phase 2a trial.
Triple-Hormone-Receptor Agonist Retatrutide for Obesity - A Phase 2 Trial.
Retatrutide, a GIP, GLP-1 and glucagon receptor agonist, for people with type 2 diabetes: a randomised, double-blind, placebo and active-controlled, parallel-group, phase 2 trial conducted in the USA.
Retatrutide in type 2 diabetes mellitus and obesity: an overview.
Retatrutide-A Game Changer in Obesity Pharmacotherapy.
Efficacy and safety of retatrutide, a novel GLP-1, GIP, and glucagon receptor agonist for obesity treatment: a systematic review and meta-analysis of randomized controlled trials.