More than a third of American six-to-11-year-olds are overweight or obese. That’s one of the alarming facts that have critics calling for a ban on vending machines and a purge of unhealthy cafeteria offerings in American schools. But a new study suggests that these temptations don’t necessarily put extra pounds on kids. In combating childhood obesity, a child’s home environment may be the more pivotal battleground, say Pennsylvania State University sociologists and demographers Jennifer Van Hook and Claire E. Altman.

 

Van Hook and Altman analyzed a nationwide study that tracked almost 20,000 children, homing in on the period between 2003 and 2007, when the kids passed from fifth grade to eighth. As they climbed the academic ladder, they were confronted with more vending machines and unhealthy snack bars. When the children were in the fifth grade, 59 percent of them attended schools with such temptations; by eighth grade, the exposure rate had risen to 86 percent. But the prevalence of unhealthy body weight did not increase. In fact, the percentage of students who were overweight or obese dropped slightly, from 39 to 35 percent.

 

One reason things don’t get worse may be that students simply don’t have much time to eat. Middle schoolers are herded from class to class, with few opportunities to pick up a sugary energy drink. It is also possible that students’ diets are already set by the time they enter middle school. Kids with unhealthy dietary habits will make poor food choices whether they are at home, in the classroom, or at the mall.

 

The authors caution that high school students, who were not included in their study, may be more susceptible to the siren song of the vending machine than middle school kids. High schoolers have more money, and more freedom to spend it.

Schools certainly have a role in promoting healthy eating and physical activity—it just may not translate into slimmer waistlines for kids, Van Hook and Altman conclude. The contents of a child’s household refrigerator seem a more promising target.