Study Questions Alleged Link Between Junk Food in Schools and Childhood Obesity
A recent study attempting “to isolate the causal effect of junk food availability
on children’s food consumption and body mass index (BMI)” has concluded
that access to competitive foods in schools “does not significantly increase
BMI or obesity among this fifth-grade cohort despite the increased likelihood
of in-school junk food purchases.” Ashlesha Datar and Nancy Nicosia, “Junk
Food in Schools and Childhood Obesity,” Journal of Policy Analysis and
Management, Spring 2012. According to the researchers, who used data from
the Early Childhood Longitudinal Study—Kindergarten Class as well as an
instrumental variables (IV) approach leveraging “the well-documented fact
that junk foods are significantly more prevalent in middle and high schools
relative to elementary schools,” the results evidently revealed that where
previous models had identified “any small positive associations” between junk
food availability and obesity, those associations became insignificant “when
controls for BMI at school entry and fixed state effects are added.”
In particular, the statistical models used by the study authors not only
suggested that “the caloric contributions of in-school junk food purchases are
likely to be small,” but that “the total amount of soda and fast food consumed
in- and out-of-school is not significantly higher among those children with
greater exposure to junk food in school (i.e., attending a combined school).” In
addition, they also found little support “for the notion that children substitute
calories from healthy foods or increase their physical activity to compensate
for increased junk food intake.”
As a result, the authors questioned legislation and regulation designed to curb the availability of competitive foods in schools while noting that further research was needed to determine whether school contracts with food and beverage companies “influence students’ food choices in the longer run through product or brand recognition.” Nevertheless, they concluded, “In light of our findings, certain policy measures, such as outright bans on competitive food sales (at least among elementary school children), might appear premature given that they remove a key source of discretionary funds.”
