Final answer:
Orlistat reduces the absorption of dietary fat by inhibiting lipase enzymes, which are essential for breaking down fats into absorbable molecules.
Step-by-step explanation:
The question How does orlistat reduce absorption of dietary fat? is best answered by understanding the role of lipase enzymes in fat digestion. Lipid metabolism in the small intestine relies on pancreatic lipases to break down fats after their emulsification by bile salts, which are released from the gallbladder and produced by the liver. Orlistat works by inhibiting lipase enzymes, which are necessary for the breakdown of fats. Without the action of these enzymes, triglycerides from the diet are not hydrolyzed into absorbable free fatty acids and are excreted undigested.