Obesity-related behaviors increase when school's out

The research was based on data from U.S. children in grades 1-12 in the National Health and Nutrition Examination Survey 2003-2008. The sample consisted of 6453 children and adolescents, some surveyed during the school year and others during a school break.

The researchers selected three main dietary measures: total calories consumed per day, number of cups of vegetables consumed, and teaspoons of added sugar, to estimate consumption of calories. They also compared student exercise patterns and screen time and any changes over the summer vacation. Data were compared for households above and below 185% of poverty, the eligibility criteria for receiving free or reduced price school lunch.

"Although obesity-promoting behaviors are generally more common during the summer break, the differences in obesity behaviors between income groups were not exacerbated during the summer break, said Y. Claire Wang, MD, ScD, associate professor of Health Policy and Management and co-director of the Mailman School's Obesity Prevention Initiative.

Using the U.S. Department of Agriculture's recommended guidelines, overall, students at all grade and income levels throughout the year routinely did not meet the recommended levels of vegetable intake, consumption of sugary sweetened beverages, and exercise, and exceeded the recommended amount for screen time.

In the summer, youth watched an average 20 minutes more television a day and consumed an average three ounces more sugar-sweetened beverages during summer break than during the school year. Overall, exercise was basically unchanged: students were physically active five minutes more on average than they were in school.

High school students, however, exercised significantly more during the summer than during the school year, but still did not meet standard government recommendations. In particular, those from higher-income families participated in more moderate-to-vigorous activities over the break. Lower-income teenage girls exercised less over the summer, with significantly less moderate-to-vigorous exercise.

"The school environment remains essential for shaping healthy eating and active living behaviors, and schools can play a leadership role in fostering a healthy transition from the school year to summer breaks," suggested Dr. Wang. "We see from our results a need for school-based obesity prevention efforts to go beyond the school day and the school year."

The study was funded by the Robert Wood Johnson Foundation (Grant 68162). Co-authors are Seanna Vine, Amber Hsiao, Andrew Rundle, and Jeff Goldsmith--all of the Mailman School of Public Health.