Dietary fat, an essential nutrient, is important in the feeling of satiety, but it is entirely missing from these kids diet. And we are still amazed that kids are getting fatter and fatter. So we put them on a diet (even less food or fat) and tell them to exercise, which will not have a major effect on their motivation to do even more exercise, as this article points it out. They will have less energy, as their energy is blocked by high insulin levels. After exercise, which burns up the little energy they have available, kids will be even more hungry, but we will blame their lack of willpower when they cannot resist a big mac served with french fries and fizzy drinks.
Children need dietary fat, and all isolated populations fed, especially fatty food to children. And they did not become obese, as fat is not making people fat. Refined carbohydrates and sugar do!
With a low carbohydrate diet (higher in fat), energy is not blocked by insulin, it is available in our bloodstream, so our brain will tell us to go and consume that extra energy in the form of physical activity. We do not need to tell a healthy toddler to do some exercise, his brain tells him to run around when energy is available in his body, and to rest or eat when there is no energy available.
Eating and exercising is not a question of willpower and behaviour, it is the result of underlying hormonal regulations.