You would be penalizing people for decisions made by the food industry. The very large and powerful food industry. In America, you already usually pay more money to get bread without corn syrup added to it (as just one example). It's in almost everything. YOu pay more money for the equivalent lower calorie/more natural food. Add on to that the fact that most Americans are no longer taught to cook whole foods (most never have a single Home Economics class in their education), and you have long term effects from decisions made by large social systems. Yet, we blame individuals, no matter their social class or individual biology.