NCPA - National Center for Policy Analysis


September 9, 2005

Researchers and public health officials are currently at a loss to explain the rapid rise in weight problems among children and adolescents that began in the 1980s. Concerns about the long-term health consequences of being overweight have ignited a debate about school policies that make junk food available to students in school, say researchers with the National Bureau of Economic Research (NBER).

While the revenues generated by in-school junk food sales fund a wide variety of discretionary school programs, some school district officials consider the link between junk food and overweight intuitively plausible. They have instituted policies to ban or reduce access to junk food despite the fact that little is known about whether access to junk foods in school really does contribute to obesity.

The researchers found:

  • It is the availability of junk food -- rather than advertising or pouring rights -- that is associated with weight gain.
  • In general, a 10 percentage point increase in the proportion of schools with junk food is correlated with about a 1 percent higher body mass index (BMI) for the average student.

These results, however, do not imply that every student who can buy junk food at school will become overweight. The effect of junk food availability is statistically different for adolescents whose parents are overweight, say the researchers:

  • Access to junk food in school has no effect on the 44 percent of students whose parents have normal weights.
  • For those with an overweight parent (who may have a genetic susceptibility to weight gain), a 10 percent increase in the proportion of schools that make junk food available increases BMI by more than 2 percent.

Regardless of the effect, eliminating junk food may not mitigate childhood obesity, say the researchers.

Source: Linda Gorman, "Junk Food Availability in Schools Raises Obesity," National Bureau of Economic Research, NBER Digest, September 2005. Based on: Patricia Anderson and Kristin Butcher, "Reading, Writing and Raisinets: Are Schools Finances Contributing to Children's Obesity?" National Bureau of Economic Research, Working Paper, No. 11177, March 2005.

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