 If the dog is eating a good amount of food and their weight is good, or the cat is eating an amount of food and the weight is good, chances are everything is okay. If they start gaining weight or losing weight, the first thing always you want to do is make sure there's no physiological reason for it. And therefore, once you get a clean bill of health, you understand that the way to keep a dog's weight good is no different than yours or mine.