How to help my little brother eat better?

He has to eat something, or else he won't have enough energy to preform his best. Tell him that. Your body needs food to perform, if you don't eat, you won't do as well. Also tell him if he doesn't eat, he won't grow, which is true. If the school lunch is bad, choose something healthier, like instead of the cheeseburger, have a whole wheat sandwich, any small changes.