I saw an opinion on this maybe a few weeks ago it kinda went like this: Fatties will buy healthy food, but instead of supplanting the shit food they buy with the healthy food they end up buying the shitty food AND the healthy food. The reason is because fats don't realize that eating a healthy diet is not like a crash diet, it's a lifestyle change. They aren't actually eating healthy. They are just eating more, and they don't realize it because they eat like shit in the first place.