We updated the search of a previous review. We searched 4 databases up to August 2013. We included randomized trials of primary care–relevant behavioural (diet, exercise, lifestyle) and pharmacological (orlistat) interventions for treating overweight and obesity in children and youth aged 2–18 years if 6-month post-baseline data were provided for BMI, BMI z-score or prevalence of overweight and obesity. In addition, we examined secondary health outcomes such as lipid and glucose levels, blood pressure, quality of life and physical fitness. We included any study reporting harms. We performed meta-analyses when possible, and we examined the features of interventions that showed benefits.