Retatrutide is a fully synthetic investigational peptide that is currently being studied for its effects on body weight regulation, energy metabolism, and glucose control. It is produced entirely through laboratory-based solid-phase peptide synthesis (SPPS) and is not derived from human, animal, or plant tissue. In research, retatrutide has been shown to activate the GLP-1, GIP, and glucagon receptors, which play important roles in regulating appetite, insulin secretion, energy expenditure, and fat metabolism. By targeting these three pathways simultaneously, it is being investigated for its potential to reduce food intake, increase calorie burning, and improve overall metabolic function.