OBJECTIVES:  Randomized controlled trials (RCTs) on the effectiveness of the three common bariatric surgery procedures: Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG), and laparoscopic adjustable gastric band (LAGB) in obese patients reported inconsistent results. We undertook a systematic review and meta-analysis to assess the effects of these bariatric procedures on weight loss. METHODS:  This was a systematic review and network meta-analysis of RCTs. All RCTs must include 18 years or older patients with body mass index (BMI) ≥ 35, report at least one outcome of interest, compares two of the three bariatric procedures, and follow-up of at least 1 year. Primary outcome was weight loss, expressed as BMI reduction and percentage excess weight loss (%EWL) following 1 year after the surgery. Bayesian framework with Markov Chain Monte Carlo simulation method was used for the network meta-analysis.  RESULTS:  A total of 11 unique trials were included in the analysis (8 RYGB vs. SG; 2 RYGB vs. LAGB; 1 SG vs LAGB). Nine trials (n=765) reported BMI, and the mean difference of BMI reduction for SG relative to RYGB was -0.76 (95%CI -3.1 to 1.6), LAGB vs. RYGB was -5.8 (95%CI -9.2 to -2.4), and LAGB vs. SG was -5.0 (95%CI -9.0 to -1.0). Eight trials (n=656) included results for %EWL, and the differences in means for SG vs. RYGB, LAGB vs. RYGB, and LAGB vs. SG were 3.8 (95%CI -8.5 to 13.8), -22.2 (95%CI -34.7 to -6.5), and -26.0 (95%CI -40.6 to -6.4), respectively. The node splitting analysis of inconsistency showed that the studies were consistent between direct and indirect comparisons (p>0.05). CONCLUSIONS:  There was no clear difference in effect of weight loss between RYGB and SG, although they were both superior to LAGB. Between RYGB and SG, other factors such as complications should be the primarily focus during surgical consultations.