Over the Counter Alli diet pill, showing uncomfortable side effects

Most people who shed pounds using weight-loss alli diet pill will not be able to keep the weight off. Unlike other prescription weight-loss diet drugs such as Phentermine, adipex and meridia, Alli diet pill doesn't make you feel full, reduce cravings or curb your appetite. Instead, it prevents the body from breaking down and absorbing fat.

The active ingredient in Alli diet pill is orlistat, which is found in a higher dose in the prescription diet drug Xenical. Alli diet pill blocks about 25 percent of the fat you eat; Xenical blocks one-third of the fat you ingest. For instance, a half-cup serving of Haagen-Dazs ice cream has about 320 calories and 19 grams of fat.

Alli diet pill, which is taken with meals, would prevent the body from absorbing about 4.75 fat grams or about 43 calories. If you consume about 2,000 calories a day and eat about 30 percent fat, the fat-blocking benefits of Alli diet pill would translate to about 150 calories a day. A pound of weight loss equals 3,500 calories.

To avoid the side effects, limiting fat intake to 15 grams a meal. Many Americans consume 80 to 100 grams of fat every day. Glaxo officials concede that many people would lose weight on their own with a diet that's moderate in fat, but that the pill helps them lose more weight. If you would lose 10 pounds on a diet, you'll lose 15 pounds by adding Alli diet pill to your diet.

If someone is consuming a diet already low in fat and high in carbohydrates, they likely would not get much benefit from Alli diet pill. However, doctors say most people are eating far more fat than they realize.

Orlistat has been used by an estimated 28 million people worldwide and studied in 30,000 subjects in about 100 trials. In a 1999 Journal of the American Medical Association report, 1,187 dieters, who weighed an average of 220 pounds, took either a placebo or 120 mg of orlistat (twice the dose of Alli diet pill). After one year, individuals in the orlistat group lost an average of 19.27 pounds, about 50 percent more than the 12.8-pound average weight loss in the placebo group.

But as with most diets, the dieters couldn't keep the weight off. During the second year of the study, the orlistat users were given either the 120 mg dose or switched to 60 mg, the same dose in Alli diet pill. After a year, the 120 mg users gained back seven pounds, the 60 mg users gained 9.4 pounds and the placebo group gained 11.3 pounds. So after two years on the drug, the dieters lost an average of between 10 and 12 pounds — or about 5 percent of their body weight. The placebo dieters lost 1.5 pounds.

Some dieters lost far more weight. About 50 percent of the people who use orlistat. lose at least 5 percent of their body weight. One out of five people who take the drug lose at least 10 percent of their body weight.