School-based obesity prevention programs: A meta-analysis of randomized controlled trials.

Obesity (Silver Spring). 2013 Jun 22. doi: 10.1002/oby.20515. [Epub ahead of print].  PMID: 23794226

Attempts have been made to reduce childhood obesity through school-based programs. Systematic reviews of studies until 2006 reported a lack of consistency about effectiveness of such programs. Presented is an updated systematic review and meta-analysis. 
Design and Methods: 
Replication of methodology used in previous comprehensive systematic review and meta-analysis of randomized controlled trials of school based obesity prevention programs covering studies until 2006 to review studies thru January 2012. 
Results: Based on 32 studies (n=52,109), programs were mildly effective in reducing BMI relative to controls not receiving intervention. Studies of children had significant intervention effects, those of teenagers did not, though the difference between the two groups was not statistically significant. Meta-regression showed a significant linear hierarchy of studies with the largest effects for comprehensive programs more than 1 year-long that aimed to provide information on nutrition and physical activity, change attitudes, monitor behavior, modify environment, involve parents, increase physical activity and improve diet, particularly among children. 
Conclusions: Unlike earlier studies, more recent studies showed convincing evidence that school-based prevention interventions are at least mildly effective in reducing BMI in children, possibly because these newer studies tended to be longer, more comprehensive and included parental support.