A study on supermarket location vs supermarket prices and obesity rates was published in the Journal of Public Health this week.  The lead author was Adam Drewnowski (citation and link below).
   I want to make a comment about the findings because I think one of the outcomes should be explored further.
   Without going into much detail here, the researchers reviewed shopping habits of study participants in one county in Washington state.  They asked people (during telephone interviews) where they shop for groceries (as well as their education, income, height, weight, gender, race, etc).  They used geocoding to determine the distance from the persons home to the store that they named as their primary grocery store.  They were also able to determine if the store the person chose was the one closest to their home.  Most people lived within one mile of a supermarket but chose to go to one that was about 2 miles away.
   The findings:  The distance to the store did not increase or decrease the rate of obesity. The priciness of the store where they shopped did.  
   The more expensive the store, like Whole Foods, the less likely the person was to be obese.  With statistics, a researcher can make it "as if" all the people were of the same education, race or income level and then see if shopping at a higher priced store still decreases the risk of obesity.  They did that and it did.
   So - the inverse of this is also true.  The cheaper the store the more likely it was that the shopper would be obese.  I have a theory about that and believe a second study to explore it would be quite informative. (to be clear, this one does not show cause - it is just a preliminary study that shows an interesting association)
   I believe we should review the product inventory, floor plans and promotional displays at each type of store.  Follow up research could compare the proportion of calorically dense foods sold and the number of junk food displays between low, middle and high priced stores. 
   If Walmart were studied, certainly the lowest priced grocer of all, we would see that shoppers are having to navigate a toxic food environment to get to healthier items.  They face aisle after aisle of candy and junk food displays and a fast food franchise at the store entrance.  I shop at Walmart, but I have a certain immunity to these promotions.  In my memory, nothing tastes as good as being fat felt bad.. but that is me and my history.
   See the study summary here
Adam Drewnowski, Anju Aggarwal, Philip M. Hurvitz, Pablo Monsivais, and Anne V. Moudon.  Obesity and Supermarket Access: Proximity or Price? American Journal of Public Health August 2012: Vol. 102, No. 8, pp. e74-e80.