There used to be seven basic food groups that everyone was supposed to eat every day. Let's see if I can remember what they were. Protein foods, green vegetables, yellow, and orange vegetables, fruits, dairy foods (which included eggs,) and carbohydrate foods are all I can think of. That list was replaced by five basic foods and now there's a food pyramid. Who knows what basic food lists will be created in the future?
Of course there are lots of other ways some people think we should eat in order to be healthy including the Cave Man, vegetarian, and vegan diets.
So how should we feed our kids?
While we don't all agree on the best way to eat, we do know obesity is unhealthy and has caused lots of people to have serious health problems. Most people agree that a lot of fast food is unhealthy, but busy people often don't think they have time to cook from scratch.
My advice is to listen to Aristotle and have moderation in all things. Unless there's a medical reason to avoid certain foods, we should be sure our children get as varied a diet as possible and try not to overdo any one kind of food.