Retatrutide is an investigational peptide that activates three hormone receptors: glucose-dependent insulinotropic polypeptide (GIP), glucagon-like peptide-1 (GLP-1), and glucagon receptors. Clinical research has studied retatrutide primarily for weight management and obesity, with a Phase 2 trial reporting a mean 24.2% reduction in body weight after 48 weeks at the 12 mg dose.