It's true, kids will eat when they're hungry. But there are some things to do to make sure he eats. Is he drinking milk all day long? If so, he may be getting too full for food. Limit milk to meal times, even then try to get some food in him before giving him his milk. If he seems thirsty between meals, give him a little water, but try to limit that too. Also, try letting him feed himself, put some finger foods on his high chair tray and let him do it himself. You may also want to limit his between meal snacks, so when he does sit down to eat, he'll really be hungry. Sit down with him at meals and eat too, and let him eat what you are eating. Good luck!