A common assumption of anti-fat crusaders, ranging from Super Size Me director Morgan Spurlock to the backers of restaurant restrictions in South L.A., is that poor people are especially apt to be overweight largely because they eat so much fast food, which supposedly is cheaper than healthier options. But a recent study led by J. Paul Leigh, a professor of public health sciences at U.C.-Davis, finds that poor people eat in fast food restaurants less often than the middle class. Looking at data from the Continuing Survey of Food Intakes by Individuals and the Diet and Health Knowledge Survey, Leigh and co-author DaeHwan Kim found an inverse relationship between income and fast food consumption up to an annual household income of $60,000. Beyond that point, people were less likely to eat fast food. "There is a correlation between obesity and lower income, but it cannot be solely attributed to restaurant choice," says Leigh. "Fast-food dining is most popular among the middle class, who are less likely to be obese."
Addendum: Jesse Taylor argues that Leigh's study is flawed because the data he uses come from the mid-1990s, prior to the introduction of the McDonald's Dollar Menu and similar price-cutting moves by the chain's competitors. Maybe, although the upward trend in Americans' BMIs, especially visible among people of modest means, was well under way by then.