Orlistat is a drug designed to treat obesity. It is marketed as Xenical (Roche, orlistat 120mg) or Alli (GlaxoSmithKline, orlistat 60mg). Its primary function is preventing the absorption of fats from meals, thereby reducing the energetic intake. It is intended for use in conjunction with reduced-calorie diet.
How it works
Xenical
Orlistat works by inhibiting gastric and pancreatic lipases, the enzymes that break down triglycerides (fats) in the intestine. When lipase activity is blocked, triglycerides from the meal are not hydrolyzed into absorbable free fatty acids, and are excreted undigested. The route of elimination of the undigested fats is through the feces. 120 mg three times daily before meals, orlistat prevents approximately 30% of dietary fat from being absorbed, and about 25% at the standard over-the-counter dose of 60 mg (Alli).
The effectiveness of orlistat in promoting weight loss is definite, though modest. Data from clinical trials suggest that people given orlistat in addition to lifestyle modifications, such as diet and exercise, lose about 2–3 kilograms more than those not taking the drug over the course of a year.
Side effects
The primary side effects of the drug are gastrointestinal-related, and include steatorrhea (oily, loose stools with excessive flatus due to unabsorbed fats reaching the large intestine), fecal incontinence and frequent or urgent bowel movements. To minimize these effects, foods with high fat content should be avoided; the manufacturer advises consumers to follow a low-fat, reduced-calorie diet. Oily stools and flatulence can be controlled by reducing the dietary fat content to somewhere in the region of 15 grams per meal.
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