Um... wow. That's kinda silly.
It could have a racial bonus to Jump maybe, but even so, an obese giant jumping around (in a cave, even) is a weird idea.
That reminds me! We should give them some cavey powers. Things like getting racial bonuses when underground, squeezing without penalties, etc.
Of course the cave lords are also rumored to hoard treasure, and this tempatation might prove too great for some.