Study finds National School Lunch Program contributes to weight gain

May 06, 2011

University Park, Pa. -- A team of researchers at Penn State has found that participation in the National School Lunch Program (NSLP) is associated with rapid weight gain in low-income girls. According to Daphne Hernandez, an assistant professor of human development and family studies and the study’s lead author, the results suggest that low-income girls who participate in the NSLP may be at greater risk of becoming overweight or obese than low-income girls who do not participate in the program.

The results, which are published in the April 2011 issue of the Archives of Pediatrics & Adolescent Medicine, lend support to the recent movement to create healthier lunch options for children.

“When obesity starts at a young age, it can have devastating long-term effects,” said Hernandez. “For example, pediatric obesity is associated with type 2 diabetes, cardiovascular disease, several types of cancer, and hypertension. The NSLP is intended to be a nutritional safety net for children from low-income families, but if it is contributing to obesity and, ultimately, to long-term health problems, it is not doing its job.”

To conduct their analysis, Hernandez and her colleagues used data collected by the National Center for Education Statistics, which assessed 21,260 children from 1,280 public and private schools in the fall and spring of kindergarten (1998-1999), in the fall and spring of first grade (1999-2000), in the spring of third grade (2002), in fifth grade (2004), and in eighth grade (2007). Of those students, Hernandez’s team looked at those 1,140 students whose schools participated in the NSLP and who were eligible to participate in the program based on their families’ income, which must be less than 185% of the federal poverty level or around $40,000 per year for a family of four.

“Our results tap into the larger issue of how poverty is related to weight,” said Hernandez, who said the team found that 82 percent of the children from low-income families participated in the NSLP at some point during kindergarten to fifth grade and that those children who participated persistently were more socioeconomically disadvantaged than the children who participated temporarily.

“Poor living conditions often are associated with more fast-food restaurants in the area, and with fewer opportunities for physical activity, both of which can contribute to obesity,” she said. “So, while our results suggest that the NSLP may contribute to low-income children gaining weight, it certainly is not the only cause.”

Hernandez said stress is another factor that often is associated with poverty and that can contribute to girls, in particular, gaining weight at an early age.

“Living in a stressful environment is associated with the early onset of puberty,” said Hernandez. “And when girls transition to puberty, they tend to lay down more body fat, whereas boys lay down more lean muscle.” This likely is the reason that the team did not document rapid weight gain among boys, she said.

In the future, Hernandez plans to investigate the actual foods that children are eating.

“Right now, we have no idea if the children in our study were eating the fruits and vegetables provided by the NSLP or just the à la carte items, such as chips and sodas, that sometimes are offered,” she said. “We also don’t have any information about the children’s physical activity levels. If we can get a better understanding of what children are consuming and how often they are consuming particular foods in relation to environmental stressors, we may be able to help create healthier lunch options for all children.”

For more information, contact Hernandez at, or the College of Health and Human Development Office of College Relations at 814-865-3831 or

  • Trajectories of body mass index (BMI) among girls aged 5 to 13 years from low-income families, stratified by participation in the National School Lunch Program. Click on the image above for a larger version.

    IMAGE: Daphne Hernandez

(Media Contacts)

Last Updated May 11, 2011