In this age range, systemic disease as a cause for unusual weight gain is possible, but far less commonly as is the case with dogs. Below are possible systemic causes for unusual weight gain in cats, but bear in mind that in cases when there is obesity even at this age, it most commonly is simply the result of the cat taking in more calories than it needs for its level of exercise and rate of metabolism. If your cat is obese, be sure to restrict table food to a minimum, moderate the feeding of treats, increase exercise (buy a laser pointer, install a “cat tree”, engage with cat toys, etc.), and stick to the general feeding guideline of feeding no more than one quarter of an 8 oz cup of food per 5 pounds of body weight per day. If these life style changes do not get weight off the cat within 30-60 days, then consider feeding a prescription weightloss diet, available for purchase at most veterinary clinics. If you still seek further information, please visit our Ask The Vet page to submit a one on one consultation with a licensed veterinarian 24 hours a day, 7 days a week.