Cats often develop large fat pads on the abdominal wall between the hind legs, which are sometimes confused by owners for tumors. Animals become obese for the same reasons people do. That is, they take in more calories than they burn. Metabolic diseases occasionally result in obesity, but this is a very uncommon problem in Veterinary medicine. Obesity is almost always due to a combination of too much food and not enough exercise.
Treatment of obesity consists of a combination of diet and exercise.
A number of reduced calorie foods are available and may be recommended for different situations. When a change in diet is made, it's important to remember that the animal did not gain the weight in a short period of time, so it's unrealistic to expect it to lose it all in a short period of time. Reduced calorie diets should be gradually introduced into the animal's normal diet over about a week's time. This slow transition makes it easier for the pet to adjust to the new diet without going off food, which can be particularly dangerous for cats. The day's total food should also be divided into three or four meals to help sustain the weight loss and decrease the amount of begging.