Cat Losing Weight? [13 Causes & Solutions To Weight Loss In Cats]

As a cat owner, you’ve probably been told to constantly look out for your cat gaining weight. And while it’s pretty common for cats to become overweight, sudden weight loss is also a rather serious issue that many cats suffer from, especially if there’s no obvious reason.

If your cat went from being a passionate munching fur ball to a minimalist pet that avoids food, or if your feline friend is getting suspiciously thin despite its normal eating habits, then it’s time you stop scratching your head and solve the mystery!

Unexplained weight loss can be a result of several problems, ranging from medical conditions all the way to emotional stress. In this article, we’ll be discussing 13 possible reasons your cat is slimming down.

Cat Losing Weight? 13 Reasons Why

  • Owners’ personality and lifestyle
  • Your cat’s diet
  • Depression and stress
  • Old age
  • Toothache
  • Cancer
  • Diabetes
  • Gastrointestinal complications
  • Hyperthyroidism
  • Intestinal parasites
  • FIP (Feline Infectious Peritonitis)
  • Organ failure
  • Vitamin deficiency

Now we’ll discuss each of these in more depth.

Owners’ Personality and Lifestyle

The first thing you may need to consider is your own behavior and personality since they play a vital role in the quality of care your cat is receiving. In a recent study published by the PLOS ONE journal, researchers explored the relationship between owners’ personalities and the lifestyles to which cats are exposed to, as well as how the behavior of owners affects the wellbeing of their pets.

It was found that cats often mirror their owners’ behavioral patterns such as weight-related issues. In fact, 7% of about 3000 participants had their cats rated as underweight or very underweight. These results corresponded to the owners’ struggles with weight.

Consequently, you can think of your purring pet as a little kid whose health, typically, mimics yours.

Your Cat’s Diet

Believe it or not, your pet feline does have its own preferences and requirements when it comes to food. Neglecting these needs could be the very reason your cat is losing weight.

(check out our guide on what cats can eat)

Generally, you should be keeping your cat’s food as fresh as possible to ensure that it’s palatable enough for the cat. If your pet leans towards dry food, make sure to store the stash inside an airtight container so it doesn’t turn stale. Similarly, if your cat prefers wet food, you want to keep it refrigerated since it may spoil without your notice causing your cat to avoid eating.

kitten eating

Cats can also be quite picky regarding how their food is served, taking after humans in this department. For example, if you present your cat its food in a dirty dish, chances are it won’t be happy about it to the point of actually not eating.

So if you’ve been slouching on presentation lately, try to pay more attention to the cleanliness of your cat’s food and water bowls. When serving wet food, be sure to wash the bowl before or after each meal, however, if your cat enjoys dry food, cleaning the food bowl weekly can probably slide.

As for water, the ASPCA (American Society for the Prevention of Cruelty to Animals) advises that you clean your cat’s water bowl every day to avoid hair and debris build-up.

If your cat isn’t eating often, check out our guide on how long cats can go without eating.

Depression, Anxiety, and Stress

Cats can demonstrate certain behaviors that vets associate with depression. Granted, you can’t just ask your cat if it’s anxious, sad, or depressed, or even notice evident “emotional” changes like those in humans; however, signs of depression exhibited by cats is often represented in loss of appetite.

Anorexia, which is the scientific term for losing one’s appetite and refusing to eat, can also be a result of anxiety and stress caused by your cat’s surroundings leading to weight loss. Such stressful and upsetting situations include too much noise during feeding time, the presence of other animals while trying to eat, and even the absence of another pet or routine change.

(check out our guide on why your cat won’t eat)

Your cat may also get into fasting mode if you place its food bowl close to the litter box, I mean, would you be put off if you had to eat next to your bathroom too?

Additionally, some cats may go on a hunger strike if their owner is gone for extended periods, so if you’re planning a vacation without your feline pet, it’s best if you ask a close friend to do you the favor of cat-sitting.

Old Age

Your cat may be just showing a normal change in weight that’s attributed to aging. Some old cats will fatten up, while other senior felines will simply skinny down.

According to some recent studies from Dr. David Williams, a professor in the Department of Veterinary Clinical Medicine at the University of Illinois, aging cats starting from 8 years can suffer from a decline in intestinal functions along with associated weight loss.

Moreover, senior cats usually suffer from a declining sense of smell and dental issues that, in turn, may affect their love of munching on food.


If your cat is normally healthy and of young age, yet suddenly begins showing mysterious disinterest in its favorite meals and starts to shed too many pounds, the culprit could be right under your pet’s nose, literally!

Having a sore tooth can cause your cat enough pain and discomfort to completely desert the food bowl, similar to how you yourself would behave if your teeth hurt.

If you notice your cat excessively drooling or pawing at its mouth, make sure to quickly have it checked up. You don’t want the condition to progress into more severe mouth ulcers and gingivitis.


As scary as it is, cancer could potentially be the reason your cat is losing weight. Although not the most frequent cause of weight loss in felines, cancer remains a fairly common culprit.

Unrecognizable male veterinarian listens a sick black-white cat

Additional symptoms of cancer affecting internal organs that may also appear on your cat include loss of appetite, weakness, and lethargy.

If you happen to discover a lump on your cat’s body, you should immediately seek professional medical help for further diagnosis and treatment.


Feline diabetes, similar to diabetes in humans, is a medical condition that occurs when the body fails to produce adequate (if any) amounts of insulin hormone or develops resistance to insulin so it doesn’t efficiently respond to the hormone action.

This leads to an increase in blood glucose levels along with an inability of the body cells to uptake glucose. Since glucose is the main source of energy for living creatures, its absence from the cells requires the body to look for alternative energy sources such as fats and proteins. The breakdown of such compounds primarily causes weight loss in cats.

More symptoms of feline diabetes include repeated urination, abnormal thirst, and urinary tract infections.

Gastrointestinal Complications

When it comes to your cat’s gastrointestinal system, there’s quite a number of possible conditions and diseases that may lead to reduced appetite as well as subsequent weight loss.

Some of the common gastrointestinal problems in cats that could result in weight loss include an imbalance of gut flora, allergies, IBD (Inflammatory Bowel Disorder), and dysfunctional small intestines. Additional symptoms may appear as diarrhea or vomiting.


Also known as thyrotoxicosis, hyperthyroidism is a rather seen disease in cats, particularly those of middle age and older. This condition happens when the body produces excessive quantities of thyroid hormones (T3 and T4) due to the overactivity of an enlarged thyroid gland.

These hormones are greatly responsible for metabolism and the elevation of their levels mainly manifests itself through significant weight loss accompanied by a contradictory increase in appetite.

Intestinal Parasites

One of the most prevalent problems in cats affecting 45% of some feline populations, intestinal parasites could very well be the reason your cat is slimming down.

Symptoms of intestinal parasitism usually consist of loss of appetite along with weight loss, anemia, diarrhea, and vomiting. Examples of such parasites include hookworms as well as stomach worms.

Feline Infectious Peritonitis (FIP)

Feline infectious peritonitis is another possible reason your pet is losing weight. This viral disease is pretty common among cats in catteries as well as houses with multiple cats living together.

Sleeping cat

In a recent retrospective study of 286 cats suffering from neurological diseases, 97 cats were found to carry an infectious disease. 48% of those cats we diagnosed with FIP.

Besides neurological symptoms, FIP causes weight loss, fever, pica, and anorexia.

Organ Failure

As we’ve already established, elderly cats frequently experience changes in metabolism which could be masking other underlying problems such as kidney disease.

Such a condition develops on a chronic level and fully kicks in as the cat gets older. According to a recent study, weight loss can be detected in association with chronic kidney disease (CKD) before diagnosis, becoming more aggressive after diagnosis.

Vitamin Deficiency

Vitamins are crucial to maintaining healthy metabolic activities inside a cat’s body, which is actually incapable of synthesizing some critical vitamins on its own, and so these nutrients must be present in your cat’s diet.

For example, Niacin deficiency is proven to cause weight loss that could, unfortunately, result in death. Other vitamins linked to weight loss include vitamins A, E, and B12.

Wrap Up

Carefully studying our list of reasons for weight loss in cats, we can conclude that a proper diet along with regular check-ups and early veterinary intervention is key to a healthy life for your feline friend. If you’re looking to help your cat add some extra pounds, check out our best high-calorie cat food for weight gain.

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