I'd like to look at this another way. Based on a case study of 1, my belly is clearly built in personal protective equipment.
In the past year I broke a femur, parted with my ACL and MCL, tore my calf, and mistreated my shoulder. The day after a race my neck, arms, and legs ache.
Never has my belly been injured, hurt, sore, or complained the next day - not once! I feed it a beer and a burger after a race and it is always ready for more.... I meant racing not beer..... OK well that too.
Evindence clearly shows without my belly that I would likely have ruptured my spleen, bruised a liver, perforated an intestine or something else awful.
Then there is the stealth factor. Nobody worries about me beating them when we are at the starting gate and if I do they have this excuse, "clearly had a really bad race, even the fat guy beat me."