Summer is a welcome respite from the rigor and routine of the school year for many children but unfortunately it can often lead to weight gain.

A study led by Dr. Jennette Moreno of the USDA/ARS Children’s Nutrition Research Center at Baylor College of Medicine showed that children gained weight during the summer but lost weight during the school year.  The research was included in a recent issue of the Journal of School Health.

“Kids tended to see an improvement in their weight during the school year but during the three short months of summer, we saw a dramatic increase,” said Moreno, an instructor of pediatrics – nutrition. “There was a particularly pronounced summer weight gain in children who were already overweight or obese.”

The study included more than 3,700 children in a Southeast Texas school district. They were enrolled in the study upon starting kindergarten in 2005 and followed throughout elementary school. The children were classified into one of four weight categories at the beginning of the study based on initial body mass index percentiles – underweight, normal weight, overweight, or obese.

Their heights and weights were measured in the fall and spring of each school year. Children in all weight categories gained weight over the summer; however, it was most significant among overweight and obese children. Only the overweight and obese children lost weight during the school year, with children in the other categories remaining the same.

There are several possible explanations for increased weight gain during summer  compared to the school year, Moreno notes. One is that some of the policies that have been enacted like national school lunch and breakfast programs as well as requirements for physical activity during the school day are in fact beneficial to kids. Also, the school day provides more structure, and children do not have unlimited access to food during the day. Although not directly studied, these factors may help to promote healthy lifestyles, she said.

During the summer, however, there is potentially less structure for children. They likely have more access to food throughout the day while at home and may be engaging in more sedentary behavior, like watching television and playing video games, while having less structured physical activity.

“This study points to the fact that during the summer, more attention needs to be paid to a child’s eating and physical activity habits,” Moreno said. “It also indicates that not just a select group of severely obese kids but all kids need something in the summer in terms of intervention to prevent this slide toward obesity.”

Future research will evaluate the weight gain from one year to the next to try determine if it is a pattern that takes place over time, or if the weight gain is happening at a specific point during elementary school.

“The suggestion so far is that it’s happening right after kindergarten but additional research will offer more direction,” Moreno said.

Others who contributed to the study included Dr. Craig Johnston of the CNRC and Deborah Woehler of the Oliver Foundation. Funding for the study was provided by the Oliver Foundation.

The CNRC is committed to increasing consumer awareness of the role of childhood nutrition on health and life-long well-being and of the contributions of center scientists. This information is provided as a community service. Content is presented as an educational resource and should not take the place of advice and recommendations of your personal physician. If you suspect you have (or your child has) a health problem, visit your health care professional. Links to other web sites are considered an extended service but are not controlled or endorsed by the CNRC or Baylor College of Medicine.