I have a female 8 year old mixed breed cat. She has always been a little stocky, but now she is getting obese. She was a rescue cat, and she's very skittish. She doesn't let us pick her up, and runs away if we approach her too quickly. It would be almost impossible to bring her to a vet. She also lives with another 5 year old male cat. Is there a way I can safely put her on a diet without it affecting my other cat?