The only exercise needed in most households is for parents to exercise their thumb by turning off the TV and sending the kids outside to play.
Consistant video games/TV + junkfood = fat kid.
I disagree. The main problem is nutrition. Kids are fed crap because its economical and it tastes good. The breakfast cereals are pure sugar, the "lunch packs" are processed and empty calories. Visits to McDonalds, Cold Stone, etc really add up. The calorie content is significant. It took me 80 minutes in the gym of high intensity cardio to burn off 1 pint of Ben and Jerry's ice cream - I'm an adult, weigh ~2-3x as much as an average kid, so I'm not convinced that some simple outdoor recreation is enough to combat the empty nutrition they encounter on a daily basis. Hell, even the schools provide pure crap: french fries at lunch, ice cream sandwiches, fruitopias.
My parents were stationed in Germany for 3 years. I was forced to spend most of my time outside of school in a daycare. There wasn't much food, and they basically kept me confined in a small arts and crafts room. I was sedentary, yet did not gain weight because I didn't eat an excess amount of food. As soon as we moved back to the states (age 11), I took up soccer, basketball, and baseball in middle school. Long practices, plenty of activity, but I put on a ton of weight: I attribute it to egg/sausage biscuits and cheese danishes at McDonald's.
I think, in general, people grossly overestimate the number of calories they burn daily.
Exercise is never a substitute for portion control.