The study says that both food deserts and food swamps contribute to obesity. Also: > The present study has limitations. First, as noted by Dunn, highw

The study says that both food deserts and food swamps contribute to obesity. Also: > The present study has limitations. First, as noted by Dunn, highways are an imperfect instrument. There were 1672 counties with no highway exits, so this IV approach did not provide information about counties where the food environment is not associated with the number of highway exits. 1672 counties is more than half the country. I recommend reading the rest of the Limitations section as well.