If it is in the winter, you can plan for woollen clothes that will definitely keep him warm and avoid his catching of the colds or the flu.
Made in USA Clothing for Kids
This includes Caffeine, Green Tea and Glucomannan (a fiber that can reduce appetite). However, the results are usually weak and inconsistent and certainly nothing to get excited about. At the end of the day, the only thing that is really proven to help you lose weight is changing your diet. Exercise can help too, but what you eat is by far the most important.
For a proven way to lose weight without hunger, check out this article.