Our Cindy cat is a real chubbs butterball and I began restricting her food intake. She, too, would feast on a portion of canned food and then her dry food all day and as I observed her, she would eat much more dry food than Lucy. Lucy, by contrast, is sleek and as fast as lightning. So, this is sad, but our vet recommended putting Cindy on an adult maintenance or adult lite diet and she's just about a year old! Now I give them a portion of canned food in the morning followed by some dry food in a dish, but I take the food away during naptime and when they go in for the night. No more all you can eat around here!
Our vet said that cat food is loaded with calories (kitten food is probably worse). After thinking about cheaper brands of cat food, the Friskies canned food has probably less calories because it is composed of more water and if you know anything about diet programs, they often advise you to drink 6-8 glasses of water a day.