School Interventions Effective For Childhood Obesity Prevention, Control

DERBY — A team of researchers at the Yale-Griffin Prevention Research Center (PRC), publishing in the current issue the International Journal of Obesity, have shown that interventions in school for obesity prevention and reversal do, in general, exert a beneficial effect. Over recent years, health professionals have questioned the utility of school-based intervention for obesity control, and the topic has been actively debated at the meetings of The Obesity Society.

“Schools can conceivably play an important role in reducing obesity levels. However, as pointed out in two recent systematic reviews of school-based interventions, the ability to draw conclusions regarding the efficacy of school-based interventions continues to be limited given the small number of published studies and issues with methodology,” noted Dr David Allison of the Clinical Nutrition Research Center of the University of Alabama at Birmingham, and formerly president of The Obesity Society, writing in an editorial that accompanied the research paper.

“While it may seem intuitive that interventions in school are vital to turning the tide of epidemic childhood obesity, there has been lack of consensus among experts, partly because clear evidence of effectiveness just wasn’t there,” acknowledged Dr David L. Katz, lead investigator of the current study, and director of the Yale-Griffin PRC.

To learn how effective school-based strategies can be in preventing or controlling obesity, the Yale researchers conducted a systematic review and meta-analysis of studies published on the topic. A meta-analysis combines the data from separate but related studies to evaluate the pooled results.

The research team considered school-based intervention studies published in peer-reviewed journals between 1966 and 2004. They searched for studies that tried to help children manage their weight or prevent unnecessary weight gain, and that used strategies involving nutrition, physical activity, reduced TV watching, or some combination of these strategies.

Dr Katz’s team considered 64 studies for inclusion. After eliminating studies that failed to meet criteria for inclusion or for quality standards, they whittled their list down to 19 studies involving students in elementary, middle, or high schools. Of these, eight had enough data to include in the meta-analysis.

Based on the meta-analysis, the Yale research team found that combined nutrition and physical activity interventions led to significant reductions in body weight. When looked at individually, the nutrition interventions and TV reduction were also effective; programs based on physical activity alone generally did not lead to a reduction in body weight.

“Everyone should recognize the urgency of the obesity epidemic in children,” said Dr Katz. “We are watching children develop what was, not long ago, ‘adult onset’ diabetes, now called type 2. We are seeing signs of heart disease risk in ever younger people. The need to fix this is extreme, but the means of doing so have proven elusive.

“Our paper shows that schools can, indeed, be part of the solution — and therefore should be, because the only alternative is to be part of the problem! However,” Dr Katz noted, “it is unreasonable to expect that schools can be the entire solution. There is a flood of obesity-causing influences into our daily lives every day from every direction, in the form of tempting calories and barriers to physical activity. Interventions in schools are like one sandbag in a levee to hold back these flood waters; we will need to stack a lot of sandbags before we find ourselves back in comfort on dry land.

“We do share the common a priori intuition that schools can play an important role in promoting healthy body weights, but new out-of-the-box ideas are needed to try and develop approaches whose results will support that intuition. Thus, for future school-based interventions, we advocate novel approaches and use of smaller efficacy studies rather than larger effectiveness trials,” wrote Dr Allison.

The Yale-Griffin PRC has developed two such “out-of-the-box” programs, one for nutrition education, called Nutrition Detectives (www.davidkatzmd.com/nutritiondetectives.aspx), and one for physical activity, called ABC for Fitness (www.davidkatzmd.com/abcforfitness.aspx). Initial evaluation of both programs, available to all schools for free, suggest both health and academic benefits.

Dr Katz advises that future studies should examine different combination of intervention components to determine the optimal way to blend different intervention approaches.

“While this study does not provide definitive clarification of the optimal school-based strategies for obesity prevention and control, it does provide guidance toward rational guidelines, along with hopeful evidence that we’re making real progress. No single intervention, in school or elsewhere, is likely to be enough to reverse the childhood obesity trend,” Dr Katz concluded. “Since the obesity epidemic has been created by an array of factors in modern society, combating obesity will require an array of solutions. Schools can be one vital part of this solution.”