Orlistat (Alli/Xenical)

Orlistat works by forming a covalent bond with the active site of gastric and pancreatic lipases in the stomach and small intestine. These enzymes are responsible for breaking down dietary fat (triglycerides) into smaller, absorbable units (free fatty acids and monoglycerides). By inhibiting lipase activity, Orlistat prevents approximately 30% of the dietary fat from being absorbed into the body. This unabsorbed fat is then passed out of the body in the stool, leading to a caloric deficit and potentially aiding in weight loss.