As an over-the-counter weight-loss aid, Alli has a claim to fame no other similar product can make: it's approved by the United States Food and Drug Administration. That's because Alli is a reduced dose of a prescription medication called orlistat, sold as Xenical. While Xenical contains 120 mg of orlistat per capsule, Alli contains only 60 mg. Orlistat works by blocking fat absorption, which decreases the number of fat calories absorbed. The manufacturer of Alli, GlaxoSmithKline, suggests following a reduced calorie diet and exercise plan to lose weight while taking Alli.
Mechanism
Alli, a lipase inhibitor, works by blocking fat absorption in the intestine. Between 25 and 33 percent of all fat ingested will not be absorbed when you take this medication, Drugs.com reports. If you're following a reduced calorie diet of 1,500 calories per day, about 33 percent, or 500 calories, should come from fat. If 25 percent of the fat you eat is not absorbed, that means 125 calories per day are not absorbed; this is less than the calories contained in many candy bars. While blocking 125 calories assists with weight loss, it won't cause dramatic weight loss. It takes a 3,500 calorie deficit to lose 1 lb. of body weight.
Side Effects
Alli has a number of unpleasant side effects for those who choose to increase their fat intake above the 30 percent per meal recommended by the Alli literature, which equals 15 g of fat. While it might seem logical that you could eat more fat since it won't be absorbed, orlistat eliminates undigested fat in a sometimes dramatic fashion, in the form of loose, oily stools. Sudden, uncontrolled passage of oil globules or very loose stool can occur when you exceed the dietary fat limits. Other side effects include abdominal pain, headache and anxiety.
Studies
A study conducted by GlaxoSmithKline published in "The Annals of Pharmacotherapy" reported that people who took 60 mg of orlistat three times a day in addition to following a reduced-calorie diet for 16 weeks lost on average 4.8 kg of weight, or 10.5 lb. compared to 3.1 kg lost, or 6.8 lb. by those taking placebo. In addition to the 3.5 lb. weight-loss difference, people taking orlistat also had a reduction in cholesterol levels and blood pressure.
Serious Risks
Alli may cause liver damage in some people; while the FDA has not found a definite connection, the Mayo Clinic website suggests that people at risk for liver disease do not take the drug. People who take immunosuppressant drugs should not take Alli, which could interfere with medication absorption. The Public Citizen's Health Research group has expressed concern over a link between Alli and breast and colon cancers, but the FDA has not found a causal relationship, Fox News reported in 2007.
References
- Drugs.com: Alli
- "The Annals of Pharmacology"'; Low-Dose Orlistat Effects on Body Weight of Mildly to Moderately Overweight Individuals: A 16 Week, Double-Blind, Placebo-Controlled Trial ; James Anderson, M.D.; Susan M Schwartz, Ph.D.; Jonathan Hauptman, M.D., et al; August 29, 2006
- Mayo Clinic.com: Alli Weight-Loss Pill: Does it Work?
- Fox News: Group: Diet Drug Alli Linked to Colon Cancer
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