My stepson is also obsessed with food, bread and apples are his staple backups! After a massive bowl of cereal he asks for another, and after that one he will happily eay an apple. He literally eats us out of house and home. He too eats too fast, doesn't chew enough, just throws it down his throat.
However, because of his ADHD meds he loses all appetite! So we are having the opposite issue at the moment, he isn't gaining enough weight or growing as fast as he should be.