It's back-to-school time — time to buy clothes and school supplies and get ready to spend seven or eight hours a day out of the house. Many students will be participating in government-funded school breakfast and lunch programs. The intention of these programs — to make sure children have enough food to eat so they can learn — is good. Unfortunately, their impact on children’s health may not be so positive.

Researchers found something disturbing when they looked at both long- and short-term participation in school meal programs to determine their effect on the body mass index (BMI) of students. They tended to make kids fat. The longer the children participated in the programs, the greater was their risk of being overweight.

Extra policy support may be needed to fund chef-to-school and farm-to-school programs, as well as culinary training for cafeteria workers, so students will actually eat what is prepared for them.

The Virginia Tech researchers followed over 21,000 children from kindergarten to eighth grade and found that the students who consistently took part in both the school breakfast and lunch programs during their elementary and middle school years were the children most likely to be overweight.

These kids ate one-third to one-half of their meals at school. Children in the South, the Northeast, and rural parts of the country showed the most negative effects of the programs, especially fifth graders in the South and eighth graders in the Northeast. The longer the children participated in the programs, the higher their risk of being overweight.

It’s especially concerning that this study comes on the heels of new legislation for school meals because the nutritional goals of the previous standards were not producing satisfactory results. The Healthy Hunger-Free Kids Act of 2010 increased nutrition quality standards for government-funded school programs beginning with the 2014-2015 school year, and the Community Eligibility Provision of the act provides free meals to all students who attend schools in high-poverty areas. This means millions more students will be receiving free meals at school.

“The question now is what to do in order to not just fill bellies, but make sure those children consume healthy and nutritious food — or at least not contribute to the obesity epidemic,” Wen You, one of the study authors, said in a statement.

Providing food is a good and necessary first step, but policymakers need to look at all aspects of school meal programs, from their availability and affordability to their nutritional quality and appeal to students, the researchers believe. Extra policy support may be needed to fund programs such as chef-to-school, farm-to-school and culinary training for cafeteria workers so students will actually eat what is prepared for them, according to You.

This study shows there is still a need to improve the effectiveness of school meal programs and promote better nutrition among children, but something also has to be done beyond that so schools to do more than just meet arbitrary government standards.

Schools are the perfect place to make some progress in the battle against childhood obesity. With millions of students eating up to half of their meals at school, they offer an opportunity to find a way to balance providing nutritious food with the taste preferences of school children. It's not easy, but the more schools take healthy nutrition seriously, the more likely it is that tasty and healthy solutions will be on the menu.

The study is published in the journal, Health Economics.