A meta-analytic review of obesity prevention in the schools: 1997-2008

A meta-analysis was conducted on school-based interventions to reduce obesity in children. Sixtysix (k = 66, N = 31,059) comparisons from 40 published studies from 1997 through 2008 were included in analyses. Results indicated a significant effect for school-based interventions with an overall weighted effect size of r =. 05. Several moderating factors were examined to explain the heterogeneity in study outcomes. Interventions that were universal (k = 37, r = .07), conducted in elementary schools (k = 41, r = .06), implemented collaboratively (k = 19, r = .12), primarily included children of Asian ethnicity (k = 5, r = .30), encouraged nutritional change (k = 28, r = .13), and sought to reduce sedentary behaviors (k = 17, r = .15) were identified as more successful in reducing students' obesity-related outcomes. Factors that resulted in negative effects for school-based programs included interventions of short duration (k = 11, r =-.04) and those that implemented system-wide changes in nutrition (k = 15, r =-.03). The variability in study effect sizes is discussed, and recommendations are made for future school-based interventions targeting children.