About Orlistat Anti-obese drug. Saturated derivative of lipstatin. Mechanism of Action of Orlistat Its primary function is preventing the absorption of fats from the human diet, thereby reducing caloric intake.Orlistat works by inhibiting gastric and pancreatic lipases, the enzymes that break down triglycerides in the intestine. When lipase activity is blocked, triglycerides from the diet are not hydrolyzed into absorbable free fatty acids, and are excreted undigested instead.