Even though many schools fall short when it comes to offering daily physical education and balanced meals, children are more likely to pack on pounds during summer break than during the school year.

A study based on twice-yearly body mass index (BMI) measurements from 5,380 children in 310 schools found that BMI gains were faster and more variable during summer vacation than during the kindergarten and first grade school years. In addition, the difference between school and summer gain rates was highest among three subgroups at high risk for obesity: black children, Hispanic children and children who were already overweight at the beginning of kindergarten.

"Do schools contribute to childhood obesity? They may, to some degree, but it appears that other factors are more to blame," the study's authors said. They suggested that school-based interventions aimed at helping kids learn healthy habits should "target children's behavior not only during school hours, but also, and most importantly, after the bell rings." [From: "Changes in Children's Body Mass Index During the School Year and During Summer Vacation" Contact: Paul T. von Hippel, MAS, PhD, Ohio State University, Columbus, Ohio; Brian Powell, Indiana University; Doug Downey, Ohio State University]

The American Journal of Public Health is the monthly journal of the American Public Health Association (APHA), the oldest organization of public health professionals in the world. APHA is a leading publisher of books and periodicals promoting sound scientific standards, action programs and public policy to enhance health. More information is available at http://www.apha.org.