The authors found that 59.2 percent of fifth graders and 86.3 percent of eighth graders in their study attended schools that sold junk food. But, while there was a significant increase in the percentage of students who attended schools that sold junk food between fifth and eighth grades, there was no rise in the percentage of students who were overweight or obese. In fact, despite the increased availability of junk food, the percentage of students who were overweight or obese actually decreased from fifth grade to eighth grade, from 39.1 percent to 35.4 percent.
“There has been a great deal of focus in the media on how schools make a lot of money from the sale of junk food to students, and on how schools have the ability to help reduce childhood obesity,” Van Hook said. “In that light, we expected to find a definitive connection between the sale of junk food in middle schools and weight gain among children between fifth and eighth grades. But, our study suggests that—when it comes to weight issues—we need to be looking far beyond schools and, more specifically, junk food sales in schools, to make a difference.”
According to Van Hook, policies that aim to reduce childhood obesity and prevent unhealthy weight gain need to concentrate more on the home and family environments as well as the broader environments outside of school.
“Schools only represent a small portion of children’s food environment,” Van Hook said. “They can get food at home, they can get food in their neighborhoods, and they can go across the street from the school to buy food. Additionally, kids are actually very busy at school. When they’re not in class, they have to get from one class to another and they have certain fixed times when they can eat. So, there really isn’t a lot of opportunity for children to eat while they’re in school, or at least eat endlessly, compared to when they’re at home. As a result, whether or not junk food is available to them at school may not have much bearing on how much junk food they eat.”
This study has a big sample of nearly 20,000 students and the findings were so counterintuitive that the authors waited two years to publish the results.
While this study suggests schools don’t contribute to weight gain, it doesn’t necessarily mean that schools should suddenly revert to selling all kinds of junk. At first glance, this could be the sort of study that people worried about the “nanny state” could jump on. For example, see the response of the Center for Consumer Freedom: “Maybe it’s time for the “food police” to educate themselves. All the attempts to limit choices apparently won’t do the students any good.” At the same time, schools can be part of a larger package of social forces pushing for better eating and exercise but they aren’t likely to solve the problems by themselves or by operating in simplistic ways.
I wonder if this points to a bigger issue: Americans expect that schools will be able to even a lot of social ills. In this case, being obese and overweight is a complex issue that schools themselves can’t overcome. As the authors note, there are a lot of other factors at play and by the time students reach middle school, they have already been shaped in significant ways. While education is one of the best ways to promote upward mobility and the opportunity to compete in a rapidly-changing world economy, it is not a silver bullet for all problems. Of course, public policy is limited in what it can feasibly or popularly change and politicians and advocates only have so many levers they can move.
Another thing to note: I wonder how some might see an admission from one of the authors. One author said, “We were really surprised by that result and, in fact, we held back from publishing our study for roughly two years because we kept looking for a connection that just wasn’t there.” Some might be suspicious and wonder if there is an ethical issue: did the authors data mine looking for other connections? Were the authors afraid of how some might respond to their findings? At the same time, scientists can also be surprised by their findings and I would guess they were simply being thorough before exposing their work to the public.