Somebody put that feline on the treadmill now! The weird thing about stories like this is that every cat I've ever had, or seen for that matter, only ate what it wanted to, regardless of how much food was in the bowl. These portly housecats must just keep eating even if they're not hungry.
My dog, on the other had, always eats everything presented to her. I swear if she raided the storage can of dog food she would not stop until all fifty pounds were consumed.
I have inherited my daughter's two cats (her new husband is allergic). One cat is normal size...the other one weighs almost 18 pounds and looks like a raccoon.
Both are fed the same amount, both go up and down the stairs together, and in fact, the fat cat is very quick on her feet and is always running outside when I open the door.
I can't figure out why she is so much fatter. She is healthy and agile, but she is just plain FAT!