People's consumption of fast-food becomes more common as their earnings increase from low to middle incomes, U.S. researchers suggest. Senior author J. Paul Leigh, a professor of public health sciences at University of California, Davis, said the findings weaken the popular notion that fast-food is responsible for higher rates of obesity among the poor. "There is a correlation between obesity and lower income, but it cannot be solely attributed to restaurant choice," Leigh said in a statement. "Fast-food dining is most popular among the middle class, who are less likely to be obese." Leigh and co-author DaeHwan Kim, specialists in health economics, used data from the 1994 to 1996 involving nearly 5,000 people, which included data about food consumption patterns, including restaurant visits. The researchers found eating at full-service restaurants followed an expected pattern -- as income rose, visits increased. In contrast, the study, published in Population Health Management, found eating at fast-food restaurants followed a different pattern -- fast-food restaurant visits rose along with annual household income up to $60,000. However, as income increased beyond $60,000, fast-food visits decreased, the survey said. Leigh noted that the fast-food industry attracts the middle class by locating restaurants right off freeways in middle-income areas. "Low prices, convenience and free toys target the middle class -- especially budget-conscious, hurried parents -- very well," Leigh said.