If you get your cat spayed or neutered they will gain some weight. It is good yours still gets its exercise, or he could really gain weight. I have a medium size cat that is about 8 years old. He eats a full tuna size can of canned food every morning, and has dry food available at all times. He doesn't pig out once he gets his canned food in for the day, will occasionally nibble on the dry stuff. To me when I pet him, he seems skinny~ But at night when and if he decides to come in and snuggle he will walk up my side, sometimes "make bread' for a bit then settle down for a few hours. At those times he does not seem skinny at all he is a heavy little bugger!