Yes they do, balanced with lots of activity and exercise. They need more protein,(good) fat, calcium, potassium, proper levels of sodium, and vitamin D from the sun. These help build a strong mind and body, and exercising hones that strong mind and body and it must be done consistantly from age 3 and onward.   If I ever adopt a child, ill make time day or night to indulge their thirst for athletics, to do it with them even if its a sport or activity i dont like. Why? To keep them engaged in it and keep them sharp in body and mind. Unhealthy foods will be a celebration thing(rare), not a reward because kids will want too much of it. Soda to me is like asbestos and i dont allow it in the house or around me. Im sorry something that can dissolve a iron crankcase bolt from a V8 is dangerous not just unhealthy.