Reasons why your cat might be losing weight

Cats are somewhat lethargic creatures. They take long naps, lay out in sunny areas and curl up in blankets for large portions of the day. This is perhaps why most people worry about their cats getting fat. A problem that many cat owners don’t always consider, though, is their feline friend rapidly losing weight.

It’s not always easy to detect weight loss in your cat. The fluff or fur covering most cats can serve as camouflage for weight loss until there is a big change.

The causes of unintentional weight loss in cats range from simple lifestyle changes to serious illness.

Sudden, unintentional weight loss in cats is usually indicative of a larger problem and warrants a visit to your vet to rule out serious health conditions. They will be able to run the necessary tests to determine what might be at the root of the problem.

Some of the most common causes of rapid weight loss in cats are:

Gastrointestinal problems


These are directly related to your cat’s nourishment, as problems in the gastrointestinal tract may cause your cat to lose weight. These problems may stem from inflammatory bowel disease, food allergies or other issues.



Diabetes is caused by a failure to produce insulin or an impaired ability to respond to it and can also cause rapid weight loss in cats. Other signs of diabetes include a change of appetite, excessively drinking water and excessive urination.



This is caused by a benign tumour on the thyroid, which can also lead to increased drinking and urination. This condition can lead to more severe heart problems or death if untreated.

Organ failure


Elderly cats in particular are susceptible to weight loss as a side effect of organ failure. This condition can be identified through blood and urine tests.

Stress and depression

Similarly to humans, cats can experience severe anxiety, stress and depression. These psychological problems may cause cats to stop eating, resulting in sudden weight loss. Try to identify situations in your home that may cause your cat distress, such as loud noises.



Cancer is one of the scariest and sadly one of the most common causes of rapid weight loss in cats. Often, cancer-related weight loss is accompanied by a loss of appetite, lethargy and hiding from people.

Intestinal parasites


Intestinal parasites, or worms, may also be the cause of weight loss. Worms also cause diarrhoea, bloating and vomiting. Pregnant mothers can give their kittens parasites, and they can also pass parasites through their milk when they are nursing. Cats can also get parasites from hunting and eating prey, or even by walking through contaminated grass and dirt and then grooming.

Dental problems


If your cat has inflamed gums, bad breath and signs of decay on its teeth, it may have a painful dental disease that is causing it to not want to eat. Inspect your cat’s mouth for dental problems if you notice it dropping food, chewing strangely or drooling.

Feline Viral Disease


FIP, FeLV and FIV are viral diseases in cats. These viruses have different causes and possible therapies, but weight loss is a common symptom of all three. If your vet suspects that a virus is the cause of your cat’s weight loss, they may perform tests to determine if one of these viruses is the cause.

Not getting enough food


Sometimes, your cat is eating less than you think. Do you have another cat or dog in the house? Additional pets in your home could be eating your cat’s food or obstructing your cat’s access to their food bowl. Is the food dish up high on a counter? Your cat could be experiencing pain from arthritis that is making it difficult to jump up to where the food dish is.

Dislike of a certain food


If none of the above apply, it may be that your cat is just fussy or doesn’t like a certain food. In this case, you might want to consider switching cat food brands. The Claude & Clarence complete range of healthy, natural and balanced cat foods provides optimum nutrition for your cat at any life stage.

Note: Always discuss cat weight loss with your vet. They will take a thorough history and do a complete physical exam. If a diagnosis is made, management and treatment will be based on the symptoms your cat is showing. Treatment may include prescription food, medicine and even sterile fluids that your vet can teach you to administer at home on a regular basis. The diagnosis and treatment plan will vary depending on the diagnosis.