People tend to like food that is harmful. And they tend to dislike diets that are potentially useful: most people fail to diet through failure of will, i.e. because the diet is not fun. So the evolutionary heuristic seems not to hold for food.

There are different theories why people like harmful food, but all of them try to explain the fact that they do like it. E.g., it is a purposely designed superstimulus due to competition between food sellers. Or, people evolved to want energy rich food that was rare in the ancestral environment, and when it is plentiful they actually overeat. Etc.