Its funny because Meat Loaf is or was a vegetarian. And Jim has been a vegetarian for several years now.
I am vegetarian (converted after reading interviews with Paul McCartney) but I don't find the name "Meat Loaf" to be at all offensive. To me its humurous. I think his dad started to call him Meat when he was a boy. Its part of his charm that he can make fun of himself.