Does Fast Food Contribute to Obesity?

Peter G. Klein, in his excellent, Organizations and Markets, cites a new paper that says, perhaps not.

The paper is an empirical study published in the July 2010 issue of American Journal of Agricultural Economics. Klein has this to say about the paper:

Previous research finds links between the number and density of fast-food restaurants and health problems, but has difficulty identifying cause and effect (fast food could make people overweight, but fast food restaurants could be put in areas where people are overweight anyway). Dunn uses the number of interstate exits as an instrument for restaurant location to tease out the causal relations, and finds little overall effect of fast food on obesity — none at all in rural areas, a bit in medium-density areas, and only among women and minorities.