i doubt it, because you also have to consider that time is money, and that a lot of lower income people are too busy working multiple jobs to have the time to carefully plan shopping lists, scope out the best buys, and then cook those healthful meals. or for that matter, their working hours may make it difficult to get to the grocery store when it's open... but there's plenty of fast food places open 24 hours a day. it may not cost less monetarily to eat a hamburger, but when you factor in the time cost of eating a home-cooked alternative, fast food may consume less of a lower income person's available resources.