OBJECTIVE: To assess the safety and efficacy of short-term meal replacement therapy followed by topiramate for body mass index (BMI) reduction in adolescents with severe obesity. METHODS: Adolescents (ages 12-18 years) with severe obesity (BMI >/=1.2 times the 95th percentile or BMI >/=35 kg/m2) were recruited for this double-blind, randomized, placebo-controlled trial. Participants completed 4 weeks of meal replacement therapy followed by randomization (1:1) to either 24 weeks of topiramate 75 mg/day or placebo. Mean changes were compared between groups. RESULTS: Thirty adolescents (mean age 15.2 +/- 1.7 years, mean BMI 40.3 +/- 4.6 kg/m2 ) completed the meal replacement phase and were randomized; 21 completed the study. The difference in mean percent change in BMI between the topiramate and placebo groups was not significant (-1.9%; 95% CI: -5.2% to +1.5%; P = 0.291). Significant improvements in visceral fat and very-low-density lipoprotein cholesterol were observed in the topiramate compared with the placebo group. There were no concerning changes in neurocognitive function or bone health. CONCLUSIONS: In this pilot study, 4 weeks of meal replacement therapy followed by 24 weeks of low-dose topiramate compared with meal replacement therapy alone did not result in significant BMI reduction for adolescents with severe obesity.