The percentage of food shoppers who are obese is almost 10 times higher at low-cost grocery stores compared with upscale markets, a small new study shows. Researchers say the striking findings underscore poverty as a key factor in America's growing girth. An upcoming government effort called the Healthy Food Financing Initiative will spend $400 million starting next year to bring supermarkets to low-income areas. Some researchers have suggested that simply making nutritious foods available in so-called "food deserts" is the key. But it might not be so simple, said Gary Foster, director of the Center for Obesity Research and Education at Temple. "We can't assume that access is sufficient," Foster said. "Access alone probably won't do it."