I hope this replies to the right message because my computer is acting a bit funny. If you don't mind you should probably "diet" with him. If he's eating fruit and veggies while everyone else is eating sweets and crisps then you should eat fruit and veggies too. Do fun and active stuff with him too, like going and playing fribee or football at the park. It will make it easier on him to lose weight and stay motivated knowing that you are there for him.