Growing up my family always used to have just the front claws of our cats removed, that way they still had the back ones for defense if they ever got out. One of our cats always used to sneak out and even without his front claws he would regularly hunt down birds and moles and bring them home as "presents."
One of my cats got out this past year on Christmas day and was gone for a week. When she came back she ate like crazy and gained alot of weight. We thought she was just getting bigger because she was still very young and growing. Then one day my girlfriend heard tiny meows coming from under our bed. Two kittens!
Hope your cat has been spayed!