Efficacy of exercise for treating overweight in children and adolescents: a systematic review

Background: Overweight prevalence among children/adolescents is increasing, while adult obesity may potentially cause a decline in life expectancy. More exercise is uniformly recommended, although treatment efficacy remains unclear. Objective: To determine the efficacy of exercise alone for treating overweight in children/adolescents. Design: A systematic review and meta-analysis of randomized trials published in English were completed following multiple database searches performed on December 10, 2004. Studies of isolated or adjunctive exercise/physical activity treatment in overweight/obese children or adolescents which reported any overweight outcome were included. Literature searches identified 645 papers which were manually searched, of which 45 were considered for inclusion, of which 13 papers which reported 14 studies were included (N = 481 overweight boys and girls, aged similar to 12 years). Two reviewers independently identified relevant papers for potential inclusion and assessed methodological quality. Principal measures of effects included the mean difference (MD) (between treatment and control groups), the weighted MD (WMD), and the standardized MD (SMD). Results: Few studies were of robust design. The pooled SMD was -0.4 (-0.7, -0.1, P = 0.006) for percent body fat, and -0.2 (-0.6, 0.1, P = 0.07) for central obesity outcomes, whereas the pooled WMD was -2.7 kg (-6.1 kg, 0.8 kg, P = 0.07) for body weight, all of which favored exercise. Pooled effects on body weight were significant and larger for studies of higher doses, whereas nonsignificant and smaller effects were seen for studies of lower doses of exercise (155-180 min/weeks vs 120-150 min/weeks). Conclusions: Based on the small number of short-term randomized trials currently available, an aerobic exercise prescription of 155-180 min/weeks at moderate-to-high intensity is effective for reducing body fat in overweight children/adolescents, but effects on body weight and central obesity are inconclusive. Recommendations for future study designs are discussed.