controlling a child's weight is a big challenge, as you cant cut down on his calorie intake during the growth phase . all we can do is mind the source of calories, its important to mentor the fast food calories , and avoid them as much as possible, but exercise is a good way of burning the calories away. hence get the child's ionterest in any activy that he may like, which will burn good amount of calorie. like swimming, skatting, running, dancing, martial arts .