GLP-1 (glucagon-like peptide-1) is a hormone your gut releases after eating. It tells your pancreas to produce insulin, slows stomach emptying, and signals your brain that you're full. Drugs like semaglutide and tirzepatide mimic this hormone but last much longer—days instead of minutes. Tirzepatide also activates GIP receptors, which may enhance fat burning and insulin sensitivity. The net effect is reduced appetite, slower digestion, and improved blood sugar control, leading to significant weight loss.