While 30 pounds is large for a cat, I have also seen very large cats at cat shows that are Maine Coons, although I don't think any of them were 30lbs!

Some people think its "cute" or try to have the "biggest" or whatever IMHO 30 pounds for ANY cat is a little too much. She really needs to put him/her on a diet, for the cats health and well being.....but sadly you can't tell people what to do