My colleague, public health writer Don Sapatkin, reports the following developments from a major study released this afternoon at a medical conference in Orlando, Fla.:
Tantalizing evidence that America's epidemic of childhood obesity may be starting to subside was presented Sunday by researchers who also found that the trend could be speeded up through programs in the schools.
Several recent studies reported that rates of overweight and obese children have plateaued during this decade after rising rapidly since 1980. But this is the first major study to detect a decline – of 4 percent – and it was in a national sample dominated by low-income blacks and Hispanics, the groups at highest risk.
“These are the kids you expect least to change,” said Gary D. Foster, director of Temple University's Center for Obesity Research and Education, who chaired the study of 4,603 students in 42 middle schools around the country, including six in Philadelphia. He and others speculated that the decline might be greater in the general population.
While good news, the finding was not what the researchers were looking for. Their primary goal was to determine whether an intensive, school-based effort to decrease calories and increase physical activity could make a dent in the combined prevalence of overweight and obesity, key risk factors for type 2 diabetes.
In the fall of 2006, they divided the schools into two groups. Half the sixth graders did the program; the other half were controls. When they ended as eighth graders in the spring of 2009, the rate of overweight and obese students had dropped by nearly the same 4 percent in the schools that got the intervention and those that did not.
The researchers did, however, find notable differences among subgroups and on specific measures. For example, body-mass index scores, average insulin levels and the percentage of students with the largest waists – all risk factors for type 2 diabetes – were significantly better in the intervention schools. All the effects were even stronger among students who were overweight or obese when they began the program in the sixth grade. That group, in fact, had 21 percent lower odds of being obese at the end of eighth grade compared to the controls.
Independent researchers described the study, which was funded by the National Institutes of Health with additional support from the American Diabetes Association, as the largest examination to date of attempts to reduce obesity and other diabetes risk factors through the schools.
Foster and colleagues presented the findings Sunday at the association's annual scientific meeting in Orlando, Fla. Underscoring their significance, the results were simultaneously published online in the New England Journal of Medicine.
“The study shows that a school-based program can help lower obesity and certain risk factors for type 2 diabetes in youth at high risk for the disease,” Griffin P. Rodgers, director of the NIH's National Institute of Diabetes and Digestive and Kidney Diseases, said in a statement.
Type 2 diabetes, until recently seen only in adults, has been increasing steadily in children and teenagers. The Centers for Disease Control and Prevention projects that one of every three children born in 2000 – and one of every two children in high-risk minority groups – will develop diabetes in their lifetime. People with type 2 diabetes gradually lose the ability to produce insulin and are at risk of kidney failure, limb amputations, blindness, heart disease, and stroke.
For the new study, teams of researchers developed a program to change nutrition and physical activity in the schools, bolstered by classroom curricula and communication strategies to explain and support the changes. It was a comprehensive approach. To control nutrition, for instance, all vending machines were limited to items with 200 or fewer calories, all sugar-sweetened beverages and milk with more than 1 percent fat were removed from the school, and offerings were changed not just in the cafeteria but at fundraisers and school stores.
The wide range of the interventions – particularly targetting both energy in and energy out – may explain the significance of the findings, the researchers said, and may also have made it easier for the children who were already overweight or obese to make changes without feeling singled out.
The study's failure to show that the interventions made a difference in reducing prevalence of overweight and obesity combined is not necessarily a negative, said Nicolas Stettler, an associate professor of pediatrics and epidemiology at Children's Hospital of Philadelphia. If societal rates are truly beginning to decline, as this research suggests, then that broad trend could have masked the effects of the interventions themselves, said Stettler, an expert in childhood obesity who was not involved with the study.
“A lot of schools are starting to change,” he said. They are removing sodas, reducing fat, and adding fruits and vegetables – less intensive versions of this approach. “But we still have a problem,” Stettler said, and now there is evidence for a possible solution.
“If we consider school as an important place for education,” he said, “we may also want to consider school as an important place for health promotions.”
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