What Are the Causes of Weight Gain in Cats?

A portly feline may be eating too much.
i A cat eats from a dark blue bowl on a white background image by Kapu from Fotolia.com

While a cat's weight gain is usually the result of overeating, a medical issue could actually be the cause. If your furbaby has recently put on weight, a variety of issues could be behind it. A consultation with your veterinarian may be in order to help trim down your kitty.

Caloric Intake

According to PetPlace.com, at least 25 percent of all domestic cats are obese, primarily due to the ingestion of too many calories. Avoid free-feeding your cat with a brimming bowl of food. Instead, follow the manufacturer's guidelines for his daily recommended caloric allowance. The average 10-pound cat needs only about 280 calories per day or 240 calories if obese, the National Research Council of the National Academies asserts. Measure out your cat's dry food portion and allow your cat to nibble on it throughout the day; otherwise give him several feedings of canned or dry food each day. Avoid feeding your cat food that's filled with carbohydrates and opt instead for those higher in protein to maintain him at a healthy weight, the Feline Nutrition Awareness Effort advises.

Lack of Exercise

A cat that ingests more calories than he burns through exercise will become overweight. A sedentary feline free-fed food all day will easily gain weight if not engaged in some kind of physical activity. According to the International Veterinary Information Service, cats that were encouraged to play for at least 10 minutes per day lost as much weight as a cat placed on a calorie-restricted diet. Interactive toys like laser lights and cat toys on a string entice your cat to play with you. Environmental enrichment can also help provide your cat with fun ways for him to exercise, such as the addition of a cat condo to climb, cat toys to play with and scratching posts to run his claws over. In addition, consider creating an enclosed outdoor area, such as a screened-in patio, to create a cat-friendly space in which your kitty can safely observe the outdoors.


Cats that suffer from hypothyroidism gain weight, become lethargic and have dull coats. Your kitty's thyroid gland controls his metabolism through the production of hormones; an impairment of the thyroid gland reduces these hormones, resulting in a slowing of the metabolism and therefore weight gain. Feline hyperadrenocorticism or Cushing's disease can also lead to weight gain due to increase in the production of cortisol by the adrenal glands. This condition results from a tumor or the continued use of corticosteroids to treat another illness can result in Cushing's disease. In addition, several other health issues, such as an intestinal disease or diabetes can also cause weight gain. To properly diagnose and treat your cat, bring him to a veterinarian for an exam. Plus, your vet can give you some tips on weight loss if your cat receives a clean bill of health.

Pregnancy or Swelling

If your cat is a female over 6 months old that hasn't been spayed, a possible cause of her weight gain is pregnancy. A momentary rendezvous outdoors can easily result in your cat becoming pregnant. A distended belly, a decrease in physical activity and an increase in appetite could mean your young cat is expecting kittens.

In some cases, weight gain may come not from extra body fat but from swelling or inflammation due to an internal parasite. Fluid retention in the stomach due to feline infectious peritonitis or a heart condition can mimic weight gain in cats. The growth of an internal tumor could also cause distention of the stomach.

No matter what, a visit to the vet is in order to determine the cause for your cat's weight gain or stomach distension.

Weight Loss

To avoid developing obesity-related problems and illnesses, like diabetes, your cat needs to lose weight but must do so safely. A cat that loses weight too rapidly can develop a condition known as hepatic lipidosis, a potentially fatal condition that may result in liver failure. Ideally, a cat should lose no more than around 1 percent of his body weight per week, recommends the IVIS. Reduce your cat's current food intake by about 20 percent or switch your cat to a diet cat food. Diet foods either have lower amounts of carbohydrates and higher amounts of protein or they simply have higher amounts of fiber. Eliminate snacks or treats that may have large amounts of calories and can easily sabotage your kitty's diet. Instead, replace them with healthy snacks like carrots or popcorn, recommends PetPlace.com.

Always check with your veterinarian before changing your pet’s diet, medication, or physical activity routines. This information is not a substitute for a vet’s opinion.

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