Philadelphia schools that cut out soda, revamped snack selections and took other measures to prevent childhood obesity were able to halve the odds of students becoming overweight by sixth grade, a study has found.

Among fourth-graders at five schools that instituted the new nutrition policy, 7.5 percent became overweight over the next 2 years, compared with 15 percent of students at five city schools that did not make the changes, researchers report in the journal Pediatrics.

The findings show that a comprehensive approach to battling childhood obesity in schools can make a significant difference, according to lead researcher Dr. Gary D. Foster of Temple University.

Schools have been at the center of the controversy over what to do about U.S. children’s rising rates of overweight and obesity. Critics have pointed to vending machines, sugary “a la carte” items in school cafeterias, and reductions in gym class as part of the problem.

At the same time, schools are considered the ideal place for children to learn healthy eating and exercise habits, and various school-based programs have been developed with that aim. The results have been mixed, however.

For their study, Foster and his colleagues evaluated a program developed by a non-profit community group called the Food Trust. Ten schools enrolled in the study; half were randomly assigned to adopt the nutrition program, while the other half served as a comparison group.

Schools in the program made an array of changes. They replaced soda with water, low-fat milk and 100-percent fruit juice, and rid vending machines and cafeterias of snacks that did not meet certain nutrition criteria. They educated students on how diet and exercise affect their health, and gave them raffle tickets for bikes and other prizes to reward them for choosing healthy snacks.

The schools also got parents involved through meetings and nutrition workshops that encouraged them to give their kids more fruits, vegetables and other healthy foods.

Among the 1,349 students Foster’s team followed from fourth to sixth grade. As mentioned, there was about a 50 percent reduction in the incidence (new cases) of overweight at the end of 2 years among the children attending the program schools, while no changes were seen among the children attending the schools without a program.

The prevalence (total number) of overweight children also declined during the study period in the program group. However, no differences in the prevalence of obesity were seen between the program group and the comparison group.

The results, Foster told Reuters Health, underscore the benefits of schools having a comprehensive nutrition program, rather than taking only individual measures - like removing vending machines, for instance.

He and his colleagues also stress that the urban schools in this study had largely low-income, minority student populations - children who are at particularly high risk of obesity. Black children appeared to particularly benefit from the nutrition policy.

In the sixth grade, the study found, African-American children in these schools were 41 percent less likely to be overweight than African Americans in the comparison schools.

Despite the success, Foster’s team writes, the fact that 7.5 percent of children in the program schools still became overweight shows that even more needs to be done.

They say that obesity-prevention programs should start before fourth grade, and possibly include a broader range of measures - such as devoting more time to gym class and enlisting the corner stores near schools to offer healthier snack options.

SOURCE: Pediatrics, April 2008.