MONDAY, Aug. 13 (HealthDay News) -- States with strong laws about what foods can be sold at school outside breakfast and lunch programs appear to have more students who stay at healthier weights, new research suggests.

These laws, known as competitive food laws, regulate the foods that can be sold at schools outside the school meal programs in an attempt to reduce childhood obesity. The laws cover food from vending machines, for instance, and those sold a la carte in the cafeteria, or in fundraising projects for school teams or organizations.

Few studies have gauged how successful the laws are, so Dr. Daniel Taber, a postdoctoral research associate at the University of Illinois at Chicago, decided to evaluate their effects.

He found that they do work.

"Competitive food laws in schools reduce weight gain if they are strong and consistent," Taber said.

Students exposed to strong laws gained less than those not, and they were less likely to remain overweight or obese over time compared to students in states with no such laws.

The study is published online Aug. 13 and in the September print issue of Pediatrics.

Childhood obesity has tripled over the past three decades, according to the U.S. Centers for Disease Control and Prevention. In 2008, 20 percent of children aged 6 to 11 were obese.

The study looked at data from 40 states. Of those, 11 had competitive food laws that were consistently strong or became stronger over the time period studied, from 2003 to 2006.

Taber and colleagues classified the laws as strong if they required schools to sell only foods that met specific nutrition standards. The laws were weak if they recommended but did not require sales of healthy foods, or if they used general language such as ''healthy foods'' without issuing guidelines for what qualified as healthy.

The investigators obtained health and weight data on 6,300 students in 40 states. They compared the body mass index (or BMI, a measure of weight relative to height) of students in fifth grade and then again in eighth grade.

Students who went to a school with strong laws in fifth grade gained, on average, 0.25 fewer BMI units over the three years than students in schools with no such laws.

It is difficult to translate that to pounds, Taber said. Roughly, it would be 1.25 fewer pounds for a 5-foot-tall child who started out at 100 pounds in 2003.

That was just an average, so many students gained less and some gained more, he noted.

Children who went to schools with strong laws throughout the study period gained an average of 0.44 fewer BMI units compared to those who did not. That would be about 2.25 fewer pounds for the same 5-foot-tall, 100-pound child.

The number of state laws regulating these foods has increased in recent years. A federal standard passed in 1979 prevents schools from selling candy and gum, for instance, in the cafeteria during lunch. The U.S. Department of Agriculture is in the process of updating this standard to coincide with the provisions of the 2010 Dietary Guidelines, but has not issued it yet.

The study results show that "competitive food rules are incredibly important," said Dr. Marlene Schwartz, deputy director of the Rudd Center for Food Policy and Obesity at Yale University.

"We have found that kids eat less junk food when there is less junk food in schools," she said. However, "this is the first big national study that looked at the laws."

Taber's team does not claim cause-and-effect, Schwartz noted, but they do show the importance of state laws. The study took into account many factors linked with obesity, such as income and race, she added.

Some food industry groups have lobbied against such laws, she pointed out, saying competitive foods don't make a difference in the obesity epidemic. The study, Schwartz said, suggests otherwise.

Other groups, such as the American Beverage Association, have launched programs such as their voluntary effort to reduce calories in beverages shipped to schools.

Parents who live in states without strong laws have options, Schwartz said. School districts involved in the school food program must have a committee that writes school wellness policy. Parents can ask to be on that committee.

Talk to your school administrators about your concerns, Taber suggested. Parents involved in fundraising for school teams or other projects can also suggest healthier alternatives than candy, he said.

More information

To learn more about competitive foods and how to regulate them in schools, visit the Rudd Roots Parents.

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