Exercise and BMI in Overweight and Obese Children and Adolescents: A Systematic Review and Trial Sequential Meta-Analysis

Objective. Determine the effects of exercise on body mass index (BMI in kg.m(-2)) among overweight and obese children and adolescents. Methods. Trial sequential meta-analysis of randomized controlled exercise intervention trials >= 4 weeks and published up to November 11, 2014. Results. Of the 5,436 citations screened, 20 studies representing 971 boys and girls were included. Average length, frequency, and duration of training were 13 weeks, 3 times per week, for 46 minutes per session. Overall, random-effects models showed that exercise decreased BMI by 3.6% (mean: -1.08; 95% CI: -0.52 to -1.64; Q = 231.4; p < 0.001; I-2 = 90.9 %; 95% CI: 87.6% to 93.4%; D-2 = 91.5 %). Trial sequential meta-analysis showed that changes in BMI crossed the monitoring boundary for a type 1 error in 2010, remaining stable thereafter. The number needed to treat was 5 while the percentile improvement was 26.9. It was estimated that approximately 2.5 million overweight and obese children in the US and 22.0 million overweight and obese children worldwide could reduce their BMI by participating in a regular exercise program. Overall quality of evidence was rated as moderate. Conclusions. Exercise is associated with improvements in BMI among overweight and obese children and adolescents.