The conventional wisdom is that since obesity rates are so high among the poorest Americans, that fast food is the grease-and-ketchup-soaked engine driving them upwards. But a new study on food consumption from UC Davis medical school got surprising results: It found that middle- and upper-middle income earners are the ones gobbling up the most Big Macs, Whoppers, and that artisanal pork log known as the McRib.

[Paul Leigh,] professor of health economics, said the study of the dining habits of about 5,000 Americans found that as a household's income increased, so did visits to chain fast-food restaurants such as McDonald's.

The obesity culprit amongst the poor is more likely soda, as well as packaged junk foods found in "supermarkets, convenience stores and mom-and-pop markets in impoverished neighborhoods." But a steady diet of fast food, while advertised as a recession-buster, would actually be financially out of reach for families living at or below the poverty line.

So, yeah: You're the one driving cheeseburger sales, fatty. [LA Times, Photo via thisisrobert/Flickr]