According to the U.S. Department of Agriculture (USDA), about 23.5 million Americans live in “food deserts”—areas with limited access to fresh food. But a 2011 study in the Archives of Internal Medicine finds that government policies designed to eliminate food deserts by encouraging grocery stores to open in poor neighborhoods or expand their produce offerings won’t amount to a hill of beans. 

The study, led by epidemiologist Janne Boone-Heinonen, followed 5,000 young and middle-aged adults for 15 years and found that proximity to a grocery store or supermarket did not increase consumption of healthy food. Boone-Heinonen and her five co-authors say these results “suggest that adding neighborhood supermarkets may have little benefit to diet quality across the income spectrum.”

The food desert concept is in any case full of holes, as the study’s authors acknowledge. The number of farmers markets has tripled since 1994, for instance, a fact often overlooked in surveys. And the USDA reports that 93 percent of “desert” dwellers have access to a car, which suggests poor eating habits are a matter of preference for Doritos and Twinkies, not a lack of access to leafy greens.