The Effect of Fast Food Restaurants on Obesity and Weight Gain

We investigate the health consequences of changes in the supply of fast food using the exact geographical location of fast food restaurants. Specifically, we ask how the supply of fast food affects the obesity rates of 3 million school children and the weight gain of over 3 million pregnant women. We find that among 9th grade children, a fast food restaurant within a tenth of a mile of a school is associated with at least a 5.2 percent increase in obesity rates. There is no discernable effect at .25 miles and at .5 miles. Among pregnant women, models with mother fixed effects indicate that a fast food restaurant within a half mile of her residence results in a 1.6 percent increase in the probability of gaining over 20 kilos, with a larger effect at .1 miles. The effect is significantly larger for African-American and less educated women. For both school children and mothers, the presence of non-fast food restaurants is uncorrelated with weight outcomes. Moreover, proximity to future fast food restaurants is uncorrelated with current obesity and weight gain, conditional on current proximity to fast food. The implied effects of fast-food on caloric intake are at least one order of magnitude larger for students than for mothers, consistent with smaller travel cost for adults.