Poor neighborhoods, Dr. Lee found, had nearly twice as many fast food restaurants and convenience stores as wealthier ones, and they had more than three times as many corner stores per square mile. But they also had nearly twice as many supermarkets and large-scale grocers per square mile. Her study, financed by the institute, was published in the March issue of Social Science and Medicine.
From another paper:
Dr. Sturm found no relationship between what type of food students said they ate, what they weighed, and the type of food within a mile and a half of their homes.
Here is much more.