dont forget that while the elf can get mind over body, toughness and toughness to be a fat-ass, a dwarf can get toughness-toughness-toughness, and you will have received more hp the first 15 lvls, so if a dwarf wants to be fat, h will alweys be the fattest.
Now everyone can chose the feats they want, so if the dwarf player doesent place a single toughness, and the elf player buts all feats for hp, its only fair he gets fat (and even FattER then the dwarf). besides, elves cost 20%xp more anyway.