Pharmacotherapy for obesity: a quantitative analysis of four decades of published randomized clinical trials

AIM: This article provides the first comprehensive meta-analysis of randomized clinical trials of medications for obesity. METHOD: Based on stringent inclusionary criteria, a total of 108 studies were included in the final database. Outcomes are presented for comparisons of single and combination drugs to placebo and for comparisons of medications to one another. RESULT: Overall, the medications studied produced medium effect sizes. Four drugs produced large effect sizes (ie d > 0.80; amphetamine, benzphetamine, fenfluramine and sibutramine). The placebo-subtracted weight losses for single drugs vs placebo included in the meta-analysis never exceeded 4.0 kg. No drug, or class of drugs, demonstrated clear superiority as an obesity medication. Effects of methodological factors are also presented along with suggestions for future research.