MODEL RELEASED. Xenical anti-obesity drug. Obese woman holds a bubble pack of Xenical (orlistat) anti-obesity capsules, for use in weight loss. Released in the USA in 1998, it is a non-systemic lipase inhibitor drug or fat blocker. Unlike many other diet drugs, this drug does not achieve its effect by acting on the brain. It acts on the gastro-intestinal tract to prevent the absorption of fat by about 30 percent. In a one-year clinical trial, the average patient weighing 220 pounds lost 20 pounds (10% body weight) taking Xenical on a moderately reduced calorie diet. Xenical also reduces LDL cholesterol in the blood. Obese people weigh 20% or more of their desirable body weight.