Increases in overweight and obesity rates among young children occur during summer vacations, not during the school year, according to new research from the LBJ School of Public Affairs at The University of Texas at Austin.
Paul von Hippel, an associate professor of public affairs at the LBJ School, examined body mass index (BMI) and obesity prevalence in a nationally representative sample of 18,170 children from the start of kindergarten in 2010 through the end of second grade in 2013. The results, published in the journal Obesity, provide insight into whether the causes of childhood obesity lie primarily inside or outside of schools.
Between the start of kindergarten and the end of second grade, all of the increases in overweight and obesity prevalence occurred during the two summer vacations, not during the three school years.
This study is the second nationally representative analysis of seasonal BMI gain. The first, which was co-authored by von Hippel and published in 2007 in the American Journal of Public Health, found that children gained weight faster during summer vacation than during the kindergarten and first-grade school years. However, that earlier study only followed children through first grade, and the results of the earlier study are outdated since the children who participated are now in their early 20s.
"I wish I could say that changes schools have made over the last decade are helping to reduce obesity, but they're not," von Hippel said. "Schools have never been a big part of the obesity problem. What we're seeing in elementary schools today is the same thing that we saw in 1998-2000; kids are gaining BMI at healthy rates during the school year, and then becoming overweight when school lets out. We can't make a dent in this problem if we continue to focus on school food and physical education programs that affect children only when they're at school."
Von Hippel said that school-based programs should try to change children's behaviors not only when they are in school, but also when school is out. In addition, we need to work outside schools to limit child-directed food marketing, promote out-of-school activities such as summer schools and summer camps, reduce screen time and educate parents about nutrition.
Study findings include:
- Between the start of kindergarten and the end of second grade, the prevalence of obesity increased from 8.9 percent to 11.5 percent, and the prevalence of overweight children increased from 23.3 percent to 28.7 percent.
- All of the increase occurred during summer vacactions. During the school years, overweight prevalence did not change, and obesity prevalence slightly declined.
- Because prevalence increases during the summer, it appears that major risk factors lie outside of schools.
Funding for this research was supported by the Russell Sage Foundation.