Tehran University Medical Journal

Background: Trying to find a drug with more clinical efficacy in treating obesity is one of the priorities. The aim of this study was to evaluate the efficacy of orlistat, sibutramine, lorcaserin and metformin on weight loss in obese people.
Methods: The databases of PubMed, Scopus, Google Scholar and Cochran Library were searched up to November 2016. In present study search strategy was performed by using selected keywords. Two independent investigators scanned and extracted the relevant data. The pairwise method was used to compare the difference between the mean difference weight loss for orlistat, sibutramine, lorcaserin and metformin in two direct methods (comparison of orlistat, sibutramine, lorcaserin and metformin with the control group) and non-direct (Compare orlistat, sibutramine, lorcaserin and metformin together). We assessed the quality of included trials using the quantitative 5-point Jadad scale. The heterogeneity across studies was assessed by using Cochrane’s Q and I2 tests. Publication bias was reported by means of funnel plots and Egger’s tests. 
Results: The present study performed on 36 clinical studies with a population of 3672. Our study results did show that sibutramine (mean difference -4.97 kg, 95% confidence interval -6.70 to -3.23), metformin (mean difference -4.45 kg, 95% confidence interval -9.27 to 0.38), orlistat (mean difference -2.37 kg, 95% confidence interval -3.45 to -1.30), lorcaserin (mean difference -2.36 kg, 95% confidence interval -4.58 to -0.15), respectively, had the most effect on weight loss compared with the placebo group. In addition, orlistat compared to lorcaserin (mean difference -0.01 kg, 95% confidence interval -2.47 to 2.45) resulted in more weight loss, but compared to metformin (mean difference 2.07 kg, 95% confidence interval -2.78 to 7.02) and sibutramine (mean difference 0.52 kg, 95% confidence interval -4.46 to 5.50) lead to less weight loss.
Conclusion: The present study indicated that orlistat had a greater effect on weight loss compared with lorcaserin, and had lower effect on weight loss compared with sibutramine and metformin in apparently healthy obese individuals.