J.K.
My daughter went through the exact same thing, and it was very frustrating :) I agree with the other posters, when he is done, remove the food. Once I moved my daughter out of her high chair and into a booster chair at the table, this behavior pretty much stopped altoghether. I think it must have been more fun for her to throw when she could see down from all sides, but the table seems to provide more room for her so that she isn't able to see as much as what hits the floor, therefore much less fun!