Obesity and the Availability of Fast-Food : An Instrumental Variables Approach

This paper addresses the simultaneous determination of fast-food availability on obesity rates through the use of instrumental variables, specifically the number of interstate exits in the county of residence. Using the 2005 Behavioral Risk Factor Surveillance Survey and self-collected data on the density of various fast-food restaurants in US counties, I find that a ten percent increase in the number of restaurants from the mean would increase BMI by .33 points, roughly 1.05kg for a male 1.78 meters tall and .88kg for a female 1.64 meters tall. The results are robust to the selection criteria for counties and the method yields results comparable to previous work looking at rural counties, though the sample employed here is much more generalizable