Children at greater risk of unhealthy weight gain during summer holidays, study shows

Obesity SocietyNov 2 2016

Children are at greater risk of gaining unhealthy amounts of weight during summer vacation than during the school year, according to a new study published in the Obesity journal. Researchers studied more than 18,000 kindergartners over two years and found that obesity increased only during the two summer vacations, and not at all during the school years. The results are being unveiled at the Obesity journal symposium at ObesityWeek℠, the annual conference of The Obesity Society (TOS), Oct. 31 - Nov. 4, 2016.

"Educators have long worried that summer break leads to knowledge loss, and now we know that it is also a time of excessive weight gain for our youngest school children," said Paul von Hippel of the LBJ School of Public Affairs at the University of Texas, Austin, who conducted the research with Joseph Workman of the University of Oxford. "Our findings raise questions for parents and policymakers about how to help children adopt healthy behaviors during the long summer vacation to stop unhealthy weight gain. Our results also suggest that we cannot reverse the obesity epidemic if we focus only on what children are doing and eating while they are in school."

Between the start of kindergarten and the end of 2nd grade, obesity increased from 8.9 percent to 11.5 percent of children, and overweight increased from 23.3 percent to 28.7 percent. None of the increase happened during the school years; all of it happened during the two summer breaks.

"Now that we have solid data pointing to summer vacation as a time for potential weight gain in young children, the next step is to work together to shape out-of-school behaviors," said Amanda Staiano, PhD spokesperson for The Obesity Society and Assistant Professor at LSU's Pennington Biomedical Research Center in Baton Rouge, Louisiana. "Parents can take some simple steps to help their children like sticking to a school-year sleep schedule and reducing screen time."

But parents cannot solve the problem alone. The study authors suggest that to reduce the increase in childhood obesity and overweight, school-based programs should try to shape out-of-school behaviors as well as preserve improvements made to school meals and physical activity during the school year. They suggest testing additional interventions outside of school to see what works best, but could include:
-Limited child-directed food marketing
-Promotion of out of school activities like summer school
-Increased attendance at summer camp
-Parental nutrition education.

"We hope these findings galvanize efforts by parents, educators, public health advocates and officials to make sure that summer does not set back efforts made during the school year to not just teach our children, but to keep them healthy," said Dr. Staiano.

Funded by the Russell Sage Foundation, this study used nationally representative data to objectively measure height and weight over a three-year period. Researchers used the Early Childhood Longitudinal Study to follow a national, complex random sample of 18,170 children from kindergarten in 2010 through second grade in 2013. Weight and height were measured in the schools each fall and spring, and the authors estimated growth in mean BMI, overweight prevalence and obesity prevalence during each summer and school year. The purpose of the study was to assess the importance of risk factors for weight gain both in and out of the school setting.​

Background
To assess the relative importance of school and nonschool risk factors, we estimated whether overweight and obesity prevalence grow faster during the school year or during summer vacation.

Methods
In the Early Childhood Longitudinal Study, Kindergarten cohort of 2010-2011, a nationally representative complex random sample of 18,170 U.S. children was followed from the fall of kindergarten in 2010 through the spring of second grade in 2013. Children's weight and heights were measured in schools each fall and spring. We used a multilevel growth model to estimate growth in mean BMI, overweight prevalence, and obesity prevalence during each summer and each school year.

Results
From the fall of kindergarten to the spring of second grade, the prevalence of obesity increased from 8.9% to 11.5%, and the prevalence of overweight increased from 23.3% to 28.7%. All of the increase in prevalence occurred during the two summer vacations; no increase occurred during any of
the 3 school years.

Conclusions
The risk of obesity is higher when children are out of school than when they are in.