Our cat, Brutus, weighs about 14 lbs. and is 20 months old. He's not fat, he's just a long, big kitty. We switched him to an all canned-diet about 2 weeks ago. We feed him 3 times a day on brands such as Wellness and Nutro Natural Choice, and he eats at most half of a 5.5 ounce can a day. He just doesn't eat that much at one sitting, although he has gotten better at that since we first switched him from free-feeding dry food.
Any cause for concern here? How many calories a day should a cat like Brutus get? He clearly prefers dry food as he gets extremely excited at the mere sound of our kitten's bag of dry food crinckling. He'll come running across our apartment, even if he was asleep! He doesn't do anything remotely like that at the sound of us opening up a can, or the microwave ringing, etc. I would hope that by now he's not holding out for dry food as we haven't given him a single meal of dry in over 2 weeks.
Thankfully Kit (our 4 month old kitten) has a much heartier appetite. She gets through most of the wet food that we give her (about every 4 hours when we're home), and finishes most of her dry when we're gone at work and overnight (about 1/2 cup of Nutro Natural Choice Kitten, beginning to transition to Wellness all-stages dry).