What about Alli?

Alli: The only FDA-approved OTC diet pill

Alli is the first and only FDA-approved diet pill available without a prescription. Alli contains orlistat, the same active ingredient in the prescription weight-loss drug Xenical, although at only half strength. Though it is not intended for people under 18, and is meant to be used in conjunction with a reduced-calorie diet and exercise regimen, the age recommendation doesn't appear to be monitored.

With the less-than-stellar clinical performance of Xenical in the eyes of many health experts, it's not surprising that much of the reaction to Alli's approval by the FDA was negative. Public Citizen called Alli's approval "reckless," and ConsumerAffairs.com's health advisors counsel caution. Alli's unpleasant gastrointestinal side effects have been well publicized, including uncontrollable diarrhea and oily spotting. Some critics question the usefulness of a diet drug that can be tolerated by most users only in conjunction with a low-fat diet. GlaxoSmithKline gets around the issue by marketing Alli as part of a complete weight-loss system incorporating the drug, a user-support forum and an online program called "myalliplan." Because of Alli's side effects (referred to as "treatment effects"), potential customers are warned to assess their level of commitment to a low-fat diet before they decide to use the drug. Those who do are encouraged to buy an Alli starter kit which includes a bottle of capsules, a carrying case, six information booklets and a code to access myalliplan.

Users posting to Amazon.com and Drugstore.com give Alli mixed reviews. While some dieters say the drug helps with weight loss, others find it ineffective. Even many of the most positive reviews mention the drug's unpleasant side effects. Several users say that the potential for oily spotting or other bowel issues helps them remember to keep the fat content of meals within the recommended limit of 15 grams. Others say they find the side effects inconvenient, embarrassing and even physically painful. These side effects are pretty uncomfortable for what can best be described as modest weight loss.

According to Dr. Donald Hensrud with the Mayo Clinic, the average weight loss after a year's use of prescription-strength Xenical is six pounds more than with diet and exercise alone. Since Alli is only half the strength of Xenical, Dr. Hensrud estimates that it could lead to an annual weight loss of three pounds more than what you get with diet and exercise. This modest weight loss hardly seems worth the side effects many users describe. Still, Alli is an over-the-counter weight-loss aid for which we do have clinical data. Its known side effects have at least been documented. However, Public Citizen has petitioned the FDA to remove both Xenical and Alli from the market, insisting that these drugs can be potentially harmful.