Gina Kolata in the NY Times

It has become an article of faith among some policy makers and advocates, including Michelle Obama, that poor urban neighborhoods are food deserts, bereft of fresh fruits and vegetables.

But two new studies have found something unexpected. Such neighborhoods not only have more fast food restaurants and convenience stores than more affluent ones, but more grocery stores, supermarkets and full-service restaurants, too. And there is no relationship between the type of food being sold in a neighborhood and obesity among its children and adolescents.

Within a couple of miles of almost any urban neighborhood, “you can get basically any type of food,” said Roland Sturm of the RAND Corporation, lead author of one of the studies. “Maybe we should call it a food swamp rather than a desert,” he said.

Some experts say these new findings raise questions about the effectiveness of efforts to combat the obesity epidemic simply by improving access to healthy foods. Despite campaigns to get Americans to exercise more and eat healthier foods, obesity rates have not budged over the past decade, according to recently released federal data.

“It is always easy to advocate for more grocery stores,” said Kelly D. Brownell, director of Yale University’s Rudd Center for Food Policy and Obesity, who was not involved in the studies. “But if you are looking for what you hope will change obesity, healthy food access is probably just wishful thinking.”

You can lead a man to the salad bar, but you can’t make him eat.