Reasons for a Cat Losing Weight

Weight loss can be caused by a wide assortment of conditions, but the essential underlying cause is that your cat is taking in less calories than he needs to maintain his current weight. If you notice weight loss in your cat, work with your veterinarian to determine why your cat has lost weight, and take steps to treat the problem.

Dog and cat eating food from a bowl
Large cat and small dog eating from same food bowl.
credit: humonia/iStock/Getty Images

Understanding Weight Loss

The Koret Shelter Medicine Program at the University of California at Davis reports that a normal adult cat who weighs between 8 and 10 pounds needs to consume between 180 and 220 calories daily to maintain weight. If the average-size cat takes in fewer calories, he will lose weight. If he takes in more calories, he will gain weight. Some exceptions apply -- illness could cause a cat to eat plenty but still lose weight.

Identifying Significant Weight Loss

Cats are not large animals, so it's easy for you to underestimate the gravity of weight loss: If you think losing 1 pound is no big deal, consider that a typical 10-pound cat who loses a pound has effectively lost 10 percent of his total body weight. A cat who is losing weight may appear bony or have visible ribs. His coat may be in poor condition. Take your cat to the veterinarian immediately if you see your pet dropping weight with no explanation, especially if the weight loss has occurred during a short period of time. Various medical problems can cause weight loss, and those conditions will need to be treated.

Veterinary Problems Linked to Weight Loss

Feline weight loss can be linked to any medical condition that causes a cat to lose his appetite, that prevents his body from processing and absorbing nutrients adequately, or that prevents your cat from eating. Weight loss is often a symptom of a medical condition rather than a health issue itself. Health problems that can cause weight loss include various types of cancer, feline leukemia, heart disease, kidney disease, hyperthyroidism and parasite infestation. Allergies can keep a cat from eating the way he needs to. Missing teeth, an abscess or other problems that affect a cat's mouth can cause weight loss by making it physically painful for the cat to eat. Pay attention to signs such as increased appetite, hair loss or stomach distention. Report symptoms to you veterinarian to aid his ability to determine the precise cause of the weight loss.

Other Possible Reasons for Weight Loss

Some cats refuse to eat because they've become bored with their food. Some active cats may lose weight because they simply aren't getting enough nutrients in their diet to maintain a healthy weight. Older cats often lose weight due a combination of different health conditions; some require specialized food designed to meet the needs of senior cats. Your cat may be reluctant to eat because of the way you are feeding him. If you are concerned that your cat is being chased away from his food by other pets, try feeding him separately.