I don't know how this has happened because Buttons only eats the same as the other three. In the last two or three weeks Buttons has put so much weight on I have become a bit concerned. She is only small and she is waddling. Her little legs are too small to carry excess weight. I am taking her to the vet Monday morning to make sure she is OK. Could there be some illness causing this? If she has to go on a diet how do I manage this with three other cats eating? I am thinking all sorts of things could be wrong. She is the sweetest little thing and the joy of my life.