Junk Food Not To Blame For Childhood Obesity

by Heidi Green
February 21, 2012

It seems counter-intuitive for schools to offer up “junk food” like soft drinks, candy bars, and chips alongside “brain food” like math, reading, and science, but that’s what happens in the vast majority of schools nationwide, where such foods are readily available in vending machines and snack bars. Given widespread attention to the problem of childhood obesity and recent efforts to improve the nutritional value of school lunches, eliminating such foods from school campuses seems like a natural next step.

However, a recent study suggests that banning junk foods from schools wouldn’t have a significant effect on students’ health.

Research
Sociologists Jennifer Van Hook and Claire Altman from Penn State University’s Population Research Institute conducted a longitudinal study to investigate the influence of what they call “competitive foods” (that is, those sold at school that compete with the lunch and breakfast programs) on children’s weight. They drew their data from a nationally representative sample known as the Early Childhood Longitudinal Study, Kindergarten Class of 1998–1999. Van Hook and Altman limited their analysis to the 19,450 children who attended school in the same county in both fifth and eighth grades, the years during which the survey collected data on competitive food sales in the schools.

The researchers looked at:

• children’s age and body mass index (calculated from children’s height and weight)
• competitive food sales venues at school, with data provided by school administrators
• types of competitive foods sold
• school characteristics (e.g., amenities, free and reduced-price lunch recipients, school size)
• family characteristics (e.g., parental marital status, maternal employment, family socioeconomic status, school involvement, and school choice)

Results
The researchers 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,” Van Hook explains. In fact, they found no such connection. Although the percentage of overweight and obese children in the U.S. has quadrupled during the past 25 years, and the availability of junk foods in schools has increased as well, there appears to be no association between the two.

For example, 59.2 percent of fifth graders in this study attended schools where competitive foods were sold; by eighth grade, that figure rose to 86.3 percent. In spite of the significant increase in the availability of competitive foods, Van Hook and Altman found no rise in the percentage of students who were overweight or obese. In fact, the percentage of students who were overweight or obese actually decreased during this timeframe, from 39.1 percent to 35.4 percent.

According to Van Hook, these findings seem to suggest that controlling access to junk foods at school is not an effective way of reducing childhood obesity. Rather, efforts to reduce childhood obesity should focus elsewhere, such as children’s homes, families, and neighborhoods.

This research does have some limitations. First, study tools did not collect specific information about school food sales, such as locations, hours, or rules and policies. It is possible that specific types of policies (i.e., aggressive marketing, sales at events) may be associated with student weight gain. Second, this study is particular to middle school students and cannot be generalized to high school students. Third, it is a report of population-level findings; individual students may gain weight when they have the opportunity to buy competitive foods at school. Finally, this study is not a randomized controlled trial and cannot prove cause and effect.

Recommendations
Although this study fails to find a connection between junk food at schools and children’s weight gain, parents should continue to pay attention to promoting healthy eating habits at home.

Parents of young children should pay close attention to their children’s eating habits. Research supports that children “develop eating habits and tastes for certain types of foods when they are of preschool age,” Van Hook explains, “and that those habits and tastes may stay with them for their whole lives.” Many researchers believe taste develops even in infancy, through the flavors babies experience in their mother’s milk, or even during pregnancy. In other words, the die may be cast long before middle school.

As Van Hook explains, “[s]chools represent a small portion of children’s food environment.… 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… [and] have certain fixed times when they can eat.” School, then, doesn’t provide ‘a lot of opportunity for children to eat’ or ‘eat endlessly, compared to when they’re at home.’”

Parents should provide healthy snack foods at home instead of junk foods. With more free time at home—and more time to eat—children might very well be prone to eating unhealthy snacks and bigger portions if they are readily available. Make it easy for children to grab something healthy by having fruit and vegetables (carrot sticks, green peppers, apples, etc.) washed, sliced, and plated in the fridge.

And lead by example. Display healthy habits at home that the whole family can model.