we are among the first generations in the first civilization where obesity has been correlated with poverty instead of wealth.
part of that is to lack of education and information, part of it is that people are just enticed by sugar-laden foods. but another part of it is that processed food is simply cheaper. when you load it with preservatives, etc, you can extend the shelf life. meanwhile, foods that go bad (such as produce) are more expensive. produce is far more expensive in the US - relatively speaking - than in many other places.