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Cat Weight Loss: Why Your Cat May Be Losing Weight & How To Help

By Bridget Reed


Many feline parents know to watch their furry friend’s body weight. However, you normally look for a few extra pounds or a rounder belly. That said, even though most pet parents are attentive to weight gain, it’s just as important to keep an eye out for weight loss. Many pet parents think it’s normal for their senior cats to lose weight, but that’s often inaccurate.

There are several reasons your cat may be losing. It might be something as simple as not getting enough food, but weight loss can also be a sign of more serious health issues in felines. 

If you are worried that your four-legged friend is losing a lot of body weight, it’s important to determine the cause of the weight loss with a veterinarian and devise a treatment plan. 

How Can You Tell If Your Cat Is Losing Weight?

Before taking a close look at all the different causes of feline weight loss, it is important to understand how you can tell if your cat is losing weight in the first place. Since weight loss tends to happen gradually over time, it can be difficult to determine when your cat is losing weight. It can also be difficult to tell if your cat is losing weight if they have lots of fur or used to be overweight. 

There are two simple ways to tell if your cat has lost weight. The first and perhaps the most obvious is to go based on feel. You pick your furry friend up all the time. 

If you notice that they seem lighter in your arms, it is best to bring them to the vet as soon as possible for a check-up, where they can consult their records and determine if your cat is losing weight. 

Another easy way to tell if your feline is shedding pounds is to look at old photos of them and compare their past body shape to their present body shape. Most pet parents can’t take enough photos of their feline. Those photos can serve as a helpful guide when you want to track your cat’s weight over time. 

When you look down at your cat, you should ideally see a tuck-in at the waist that is noticeable but not extreme. You should also be able to feel your cat's ribs under a thin layer of fat. If your four-legged friend’s ribs are extremely visible and prominent, they may be underweight. 

Why Does It Matter If Your Cat Is Losing Weight?

Minimizing your feline’s weight fluctuations is easy because they are negligible based on human standards. If your cat loses a couple of pounds, it might not seem worrying to you because it is only two pounds. However, losing two pounds is a big deal if your cat should only weigh 10 pounds. 

The best way to determine the seriousness of your cat’s weight loss is to think proportionally. For example, if your 10-pound cat loses two pounds, it’s equivalent to a 150-pound person losing 30 pounds. The smaller your cat, the harder it can be to detect weight loss, but even slight changes are important to note.

Why Is Your Cat Losing Weight?

Now that you know more about how to tell if your cat is losing weight and why it matters, let’s dive into some of the reasons your feline may be shedding pounds. This section will outline 11 common reasons your cat may be losing weight. 

Anxiety, Stress, Depression

Much like humans, anxiety, stress, and depression can cause your cat to lose their appetite. Your cat may become upset if there are loud noises in your home or other animals are in their feeding area. 

Cats are creatures of habit, so if there is a significant change in their routine, they may go off their food. Cats are also extremely clean, so a dirty food or water bowl or proximity of their food bowl to the litter box may also upset them. 

Toothache and Dental Problems 

If you’ve ever had a toothache, you know that eating is the last thing you want to do when your mouth is hurting. Similarly, if your feline has a toothache or another oral issue causing extreme pain, they may be less likely to eat their food which can cause weight loss. 

Felines are prone to periodontal disease, tooth fractures, and resorptive lesions. In severe cases, felines can develop stomatitis which causes intense inflammation in their mouth and gums. 

You might be able to tell if your cat has dental issues if their breath smells bad, they drool excessively, or they paw at or rub their mouth. In the worst cases, dental issues can also cause oral bleeding. 

When you bring your cat with dental issues to the vet, they will likely suggest anesthetizing them so they can do a proper dental exam. During the dental exam, they will clean your cat’s teeth and perform any necessary surgeries or tooth extractions.


Hyperthyroidism is a condition that causes your cat’s thyroid gland to become enlarged and produce too much of the thyroid hormone. It is most common in cats over seven and usually leads to weight loss accompanied by an increased appetite. 

If your furry friend is struggling with hyperthyroidism, you may also notice that they drink more, urinate more, and their coat appears ungroomed. Hyperthyroidism in cats can be treated with iodine, oral medications, changes to your cat’s diet, or surgery. 

Feline Diabetes

Feline diabetes is another common ailment that can cause your feline to lose weight. If you suspect your cat has diabetes, you need to get them medical treatment as soon as possible. Diabetes can be treated and managed with the help of a veterinarian, but without ongoing treatment, it can be fatal.

Cats with diabetes may experience weight loss and a heightened consumption of water. Usually, when cats have diabetes, they drink far more water than normal and urinate more than normal. 

Once you bring your cat to the vet, they will take blood and urine samples to determine whether or not your feline has diabetes. If they have diabetes, your vet will likely prescribe your furry friend insulin and suggest dietary changes. 

Gastrointestinal Problems 

Another explanation for your cat’s weight loss may be gastrointestinal problems. All issues concerning the GI tract will affect your cat’s weight. Cats with gastrointestinal problems often experience a reduced appetite and weight loss. 

Given that GI issues prevent your cat’s body from absorbing nutrients and digesting food properly, you may notice a more dramatic decline in your cat’s weight. 

Common gastrointestinal problems include inflammatory bowel disease, pancreatitis, and cancers of the GI tract. Along with the loss of appetite and weight loss, your cat may experience vomiting, diarrhea, and lethargy. Most GI issues require medicine and frequent treatment. 


Unfortunately, another common cause of weight loss in cats is cancer. Older felines are more prone to cancer, and cats can develop many different types of cancer. Like humans, cats can develop cancer in any part of their body. The most common type of cancer for felines is lymphoma. 

Cats with cancer often appear lethargic and are prone to hiding from their pet parents. A loss of appetite often causes weight loss associated with cancer. 

Depending on the type of cancer, the treatment plans vary. Your vet may do your feline’s blood work, test their urine, and take X-rays or an Ultrasound to determine the best course of treatment.

Feline Infectious Peritonitis

Feline Infectious Peritonitis, also known as FIP, is a virus that may be causing your cat’s weight loss. Along with weight loss, FIP will cause your cat to feel generally sick and may lead to a fever. Usually, the fever associated with FIP cannot be treated by antibiotics. 

Other feline viruses that can cause weight loss include FelV and FIV. If you bring your cat to the vet and they suspect that your feline is struggling to fight off one of these viruses, they may perform blood tests to determine if they have a virus. Depending on the symptoms your cat is experiencing, the vet will work with you to devise a treatment plan. 

Organ Failure

Another common cause of unexplained weight loss in cats is organ failure. Like cancer, organ failure is more common in older cats. If your elderly feline is inexplicably losing weight, the vet may test their organ functioning to determine if organ failure is the reason for their weight loss. 

Intestinal Parasites

Untreated intestinal parasites can also cause your feline to lose weight. Unfortunately, parasites are super common in felines. If a pregnant cat has kittens, she can pass the parasite on to her kittens. Cats also pick up parasites when they are hunting and eating prey outdoors.

Feline Kidney Disease

Another explanation for your cat’s weight loss may be chronic kidney disease, one of the most common diseases found in senior cats. Your cat’s kidneys remove waste from the blood, produce hormones, help their body regulate blood pressure, and allow for the creation of new red blood cells. 

Given that your feline’s kidneys are integral to their overall functioning, kidney disease can cause several issues. You may notice that your cat starts to drink and urinate more at first. Then, they may lose their appetite, lose weight, and become extremely sleepy and apathetic. Although kidney disease cannot be cured, your vet can help you find ways to manage the side effects on your cat. 

Not Getting Enough Food

Although it might sound too simple to be true, your furry friend may be losing weight because they are not getting enough food. Cats are sneaky eaters, so you may not always be around to watch them consume their meals. This can make it difficult to know if your feline is eating enough. 

If you have other pets in your house, they may be eating your cat’s meals or making it difficult for your cat to eat. If you recently transitioned from wet to dry food or changed kibble brand, your cat may be negatively responding to the switch by not eating enough. 

Another reason your cat may not be getting enough food is that they cannot access the bowl. Senior cats often struggle with arthritis which can make jumping and leaping difficult. If your cat’s bowl is elevated and they are older than seven, they may have difficulty accessing their food. 

What Should You Do If Your Cat Is Losing Weight?

How you treat your cat’s weight loss greatly depends on the cause of their weight loss. As soon as you detect that your cat is losing weight, you should schedule an appointment with your vet. At the vet, a physical exam and other tests will be performed to decide the root cause of your feline’s weight loss. 

If your vet determines that your cat is perfectly healthy, your cat is likely losing weight as a result of inadequate food intake. If that is the case, you may want to consider switching them from kibble to wet food or vice versa to make their meals more intriguing. 

Another undetectable condition that may be causing your cat’s weight loss is stress. If your vet agrees that your feline appears stressed, try to remove any potential stressors from their environment. 

Make sure to monitor your four-legged friend after they visit the vet, even if given a clean health bill. Sometimes, your cat’s weight loss may continue despite the changes you make to their diet and lifestyle. If this occurs, you can follow up with a visit to a veterinary specialist to get more information.

Can You Switch Your Cats Food At Any Time?

If your vet determines that your cat is losing weight due to inadequate food intake, they may suggest that you switch their food to get them to a healthy weight. Before doing so, it’s smart to consult your vet about what food you will switch your feline to so that they still get all the vitamins and nutrients that they need. 

Because cats are such particular creatures, you will need to slowly transition them from their old food to their new food. You should make the transition over the course of a week or 10 days and follow your feline’s lead. If they are extremely hesitant to try the new food, try sprinkling a little bit of their favorite treat on top to entice them. 

Regardless of how you go about switching your cat’s food, make sure you do so gradually, starting with just a bite of the new food and progressing from there to get your cat to an ideal weight. 

When Should You See a Vet About Cat Weight Loss?

As this list shows, a wide variety of illnesses and symptoms can lead to weight loss in felines. Given that the causes of weight loss range from something as simple as a pesky toothache to something as severe as cancer, it is important to bring your cat to the veterinarian as soon as you notice them losing weight. 

At the vet, they will be able to look at your cat’s medical record and determine how dramatic their weight loss is. From there, they will help you determine the cause of their weight loss and devise a treatment plan. Remember that, in many cases, your cat can be treated, and there is likely a solution to their ailment. 

Can You Prevent Weight Loss In Cats?

There is not one simple way to prevent weight loss in your feline because so many different illnesses and ailments can cause weight loss. You should regularly monitor your cat’s overall wellness and ensure routine vet visits. 

Unlike dogs, cats tend to hide injuries and illnesses extremely well. However, your vet may be able to find your cat’s health issues far sooner than they exhibit symptoms. If you notice your cat displaying any abnormal activity, bring them to the vet immediately. Treating your cat before their condition develops and worsens is always easier. 


You can tell if your cat is underweight if you can see their ribs, and there is a dramatic tuck in at their belly when you look down at them from above. Although many pet parents often worry about obesity, you should monitor if your cat loses weight because it may indicate a more serious issue. 

Kidney disease, parasites, cancer, and inadequate food are a few of the many medical conditions and lifestyle habits that can cause weight loss in cats. Regardless of what is causing your cat to lose weight, ensure you take them to the vet as soon as possible to receive care.


Feline Hyperthyroidism | Cornell University College of Veterinary Medicine

Diabetes in Cats | Symptoms and Medication | Blue Cross

Feline gastrointestinal microbiota | NIH

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