hi, are you sure he's NW due to hunger... or is it something else?
If he does eat/drink overnight, perhaps you could slowly reduce that down to encourage day eating/drinking. So if hunger at night is waking him, if he takes a bottle overnight, water it down, or gradually reduce. His day hunger should increase. Don't worry about his food intake while you adjust from day/night eating, think of the overall.
Food wise, he will eat when he is hungry (I know that's all good in theory but what about practise and for your child!!). But he may not be a big eater, he may be getting more overnight than in the day and so encouraging food in the day is an uphill battle.
If he's throwing food over the high chair, he could be not hungry, overwhelmed by too much food on the chair, or doesn't like that food. It might be a game he's playing right now, but I know DS manages to chuck all the things he doesn't want to eat or is too full for when I'm not looking. I put it back on once in case he slipped or some such, but then it comes off if he doesn't eat it. I'll try something else then get him down if he doesn't eat it. As soon as he starts to fuss he's out of the chair, I know he won't eat anymore and I respect that he doesn't want to. (I think in the long run that will work wonders).
I would resist the urge to feed him while he plays and crawls, it won't solve anything in the long run. It won't allow him to learn to eat when he feels like it, they know when they want to eat. It allows him to control his intake. Some people on here mention that kids can grazers so he eats a little frequently. I have a friend with a fiesty active boy and she allowed him to eat anywhere and it was absolutely painful. You couldn't just sit down and eat, she was forever running around after him, instead my DD new that you ate at the table and once she had her fill she was off.
Another idea, watch him for a few days, write it down if you want (that makes a huge difference to me, to see it on paper) and perhaps his hungry times don't match eating times. Actually even if you write it down, you may see he eats quite a bit overall or that your idea of how much should fill him is different than his needs. So hard to tell when they can't speak to you about it LOL
When my DD was little and I wanted her to try something new, I'd make it a game for her to help out cooking while she was hungry and she was keen to try it out (especially with no pressure to 'eat this now', she felt it was on her terms) or leave it within reach and she'd come by and try it out. It was a good way to introduce new foods, but not a long term plan.
Some things to think about.
