If you think about it, this has evolutionary advantages as well. No time to feel pain when your life itself may be in peril due to starvation. Finding food for sustenance easily supercedes recovery.
Especially if you haven't done this before, you start experiencing very strong hunger about 8-12 hours after your last meal. This is very, very much in advance of any kind of threat to your life or health from starvation. In fact, the sensation of hunger typically dulls after another 12h or so, so that if you make it past 24h of not eating, you'll typically feel less hunger than you did your first night of skipping dinner.
