The vet said that the rule of thumb is a cup of food for every 30 pounds. Which means 1/3 cup of food for 10 pounds. Which means kitties had a rude awakening coming to them when they no longer had access to 4+ cups of food at any point in time and instead were rationed 1/3 cup of food every night, to be fed to each of them in separate rooms lest Fat Hobbit eat any of The Skinny One's food. Poor, fat kitty.
A couple pages of cat layouts from a while ago: