GLP1R and obesity due to melanocortin 4 receptor deficiency: Alternatively, the monomeric compound, tirzepatide (ZepboundTM), targets both GLP-1R and glucose-dependent insulinotropic polypeptide receptor (GIPR), and was recently reported to elicit 20.9% and 25.3% weight loss in humans with obesity over 72- (10) and 88-week trials (11).