Diet Pill Sells Despite Its Side Effects

Alli (pronounced AL-eye) is a low-dose version of the prescription drug Xenical and contains orlistat, which blocks an enzyme that digests fat, so it prevents the body from absorbing about 25 percent of the fat consumed. That unabsorbed fat is then excreted through the stool.

Assuming the user follows the rules and eats no more than 15 grams of fat per meal, the side effects are supposed to be manageable. Still, they're extreme and include increased flatulence with an oily discharge, diarrhea and uncontrollable bowel movements.