I think the main problem is that kids eat the way other people in their environment eat. You usually see overweight kids with overweight parents. Young children have no way of getting themselves to McDonald's. Someone takes them or brings the food into the home. If they are hungry, they will eat what's in the home. The exception is those with true glandular/metabolic medical conditions.

When I was growing up, I can't really recall many overweight kids in my neighborhood or school. In my family, the only time we ate was at mealtime...nothing in between or in the evening. There was no snack food in our house. Everything was whole food, cooked from scratch. We had cake when it was someone's birthday. It just didn't enter our minds to eat at any other time. And we ran and played all day out side.