Diet pills are big business, but Canadian researchers have found that they result in only modest weight loss. In placebo-controlled trials, patients taking anti-obesity drugs orlistat, sibutramine and rimonabant lost more weight than those taking dummy pills, but barely. And the average weight loss was 5%, which experts say is not enough to justify the use of slimming pills.
The Canadian researchers reviewed the results of 30 placebo-controlled trials, involving nearly 20,000 obese adults who took one of the three drugs for a year or longer. The drugs did lower the risks of heart disease and diabetes in some patients, but also produced negative side effects in some, including high blood pressure and psychiatric problems.