GIP and obesity due to melanocortin 4 receptor deficiency: Originally developed to treat muscle atrophy (Amato et al., 2014), it is now being investigated in two phase 2 clinical trials in individuals with overweight and obesity: One in combination with the GLP-1 receptor agonist semaglutide (NCT05616013), and the other in combination with tirzepatide (NCT06643728), a combined GLP-1 receptor agonist and gastric inhibitory polypeptide (GIP) analogue.