I always find this statement (and the similar one about thirst) illogical.
I don't have any science to back it up - but my take is in a normal environment, you're hungry or thirst when your body needs those things. When you are working at a high intensity, it's better to fuel up appropriate ahead of time than to try to make up for it when your body realizes it needs more - because it is harder to then catch up w/ physical requirements.