Retatrutide
Retatrutide is a triple hormone receptor agonist (GIP, GLP-1, and glucagon) currently in Phase III trials. Early trial data shows up to 24% body weight reduction — potentially the most powerful weight loss peptide in development.
Where to Buy
Retatrutide (LY3437943) is developed by Eli Lilly as a next-generation obesity treatment. Unlike Tirzepatide which targets two receptors, Retatrutide adds glucagon receptor agonism to create a triple-action mechanism.
Phase II trial data published in The New England Journal of Medicine showed an average 24.2% weight loss at 48 weeks with the highest dose — surpassing every approved weight loss medication currently on the market.
The glucagon component increases energy expenditure directly, adding a thermogenic effect on top of the appetite suppression from GIP and GLP-1 agonism. This triple mechanism explains the superior efficacy.
Dosing Reference
| Beginner Dose | 1 mg/week |
| Standard Dose | 4–8 mg/week |
| Advanced Dose | 12 mg/week |
| Frequency | Once weekly subcutaneous injection |
| Cycle Duration | 24–72+ weeks |
Note: Research compound — not FDA approved. Dosing protocols based on Phase II/III trial data. Exercise caution and start conservatively.
Mechanism of Action
Retatrutide activates three complementary pathways: GLP-1 receptors suppress appetite and slow gastric emptying; GIP receptors enhance insulin response and complement GLP-1 signaling; glucagon receptors directly stimulate energy expenditure by increasing thermogenesis in adipose and liver tissue.
The net effect is a powerful reduction in caloric intake combined with an increase in caloric expenditure — addressing both sides of the energy balance equation simultaneously.
Side Effects
| Effect | Severity |
|---|---|
| Nausea | moderate |
| Vomiting | mild |
| Diarrhea | mild |
| Decreased appetite | mild |
| Heart rate increase | mild |
Research use only. All content on The Peptide Primer is provided for educational and informational purposes only. Nothing on this site constitutes medical advice. Peptides discussed are not FDA-approved for human use unless otherwise noted. Always consult a qualified healthcare professional before making health-related decisions.