✔ This article was written by a licensed veterinarian.
As a veterinarian, I’ve often heard from pet parents that their cat is starting to get a bit large. But, a question that comes in more than people realize, is: “Why is my cat so skinny?”
We’ve recently read over a topic where someone stated: “My cat is so skinny I can feel her bones.” I’ve seen many skinny cats before, and I can feel the stress of the owners who wrote about their experiences.
There are plenty of potential causes of weight loss in cats. The causes can range from old age, owner neglect, stress, internal parasites, feline cancer, or other internal diseases and health issues.
Your cat’s weight will drastically change as it grows from a young kitten to an adult cat. Much like humans, a cat’s adult weight will not remain the same throughout its life. It can go up or down depending on certain factors, such as lifestyle, age, diet, and gender.
Weight loss can occur even when your cat has a normal appetite and no health concerns. Unfortunately, that isn’t as common for your mother-in-law who just can’t shed the winter weight.
If your cat has lost weight and you start feeling its bones, it is clear that something is wrong. Take your cat to the vet because it may have some health problems that can require immediate attention.
We cover the following items in this post:
- How Skinny is Too Skinny With Cats?
- The Top 18 Reasons Why Cats Lose Weight
- Restoration To A Healthy Size: How Can I Help My Cat Gain Weight?
So, How Skinny is Too Skinny With Cats?
Determining if your cat is too skinny or not can be a real challenge. So what do you have to do?
There are two primary tools you can use when you want to determine if your little feline has the right weight:
- The Body Condition Score
- The Hand Test
The Body Condition Score
The body condition score is used to assess a cat’s weight and is similar to the body mass index for humans.
It contains two separate scales:
- One contains scores from 1-9
- One contains scores from 1-5
For simplicity purposes, we will use the 1-9 scale for this overview.
- A score of 1: The ribs are visible and obvious, there is no palpable fat on the body, the abdomen is tucked severely, and the pelvic bones and lumbar vertebrae are pronounced and noticeable. The cat is dangerously skinny.
- A score of 9: The ribs are not visible and obvious, there is palpable fat on the body, especially on the abdomen, lumbar area, and face. The abdomen has no waist. The cat is very overweight.
The ideal weight of a cat is between scores 4 and 5. Cats below these numbers are considered skinny, and cats above these numbers are considered overweight or even obese.
The Hand Test
If it is difficult to determine the body condition score for your cat, then you can try the hand test. Take your hand as a reference and feel your cat’s ribs, behind the hind legs.
- Your cat has the right weight if its ribs feel like the back of your hand.
- Your cat is too skinny if its ribs feel like your knuckles.
- Your cat is too fat if you cannot feel its ribs at all. I.e., it feels like your palm.
Remember that these tests can be used as a best guess by a cat owner, but the only way to determine a true diagnosis regarding your cat’s weight and health is to visit your veterinarian.
Why Is My Cat So Skinny? The Top 18 Reasons Why
It can be difficult to notice that your cat is losing weight if:
- The weight loss is gradual
- Your cat has lots of hair or long hair
- You have an outdoor cat that you don’t spend as much time around
- Your cat was so overweight that small changes in weight don’t stand out
In many cases, cats lose weight when they don’t eat enough. However, some diseases can cause weight loss, despite adequate food intake. Depending on the cause, it may or may not be accompanied by other signs of illness.
Here are the top 18 reasons which may explain why your cat is so skinny:
1. Their Age
Excessive weight loss in older cats is usually associated with certain diseases such as kidney or thyroid disease.
Other cats, due to their advanced age, may have musculoskeletal problems and may find it difficult to bend to the food bowl because of the pain.
Some cats may experience dental problems such as periodontitis and tooth loss, which can stop them from eating solid food due to the potential for pain while eating.
2. Intestinal Parasitic Infection (Internal Parasites)
Infestations with intestinal parasites most often occur in kittens, which are in the greatest danger. Kittens can die from intestinal worms if not treated in time.
Common intestinal worms in cats are:
- Toxocara cati
- Toxascaris leonina
- Dipylidium caninum (tapeworms)
Another intestinal parasite that can make a cat lose a lot of weight is Giardia.
In massive infestations, intestinal parasites cause nutritional disorders. They will decrease the volume of food your cat ingests, which leads to malabsorption (the body can’t take nutrients from the food your cat consumes) and malnutrition.
In other words, the intestinal parasites will consume the nutrients in the cat’s food, and your pet, although consuming food (perhaps even more than before), will continue to lose weight.
In addition to excessive weight loss, in massive infestations, your cat may have the following symptoms:
- Vomiting (with worms)
- Diarrhea (with or without worms)
- Anemia
- Swollen abdomen
3. Anorexia Nervosa (Lack of Appetite)
Anorexia Nervosa (also referred to as anorexia) is a medical condition in which cats lack an appetite, or have a decreased appetite.
The appetite of animals (and humans) is controlled by a variety of neurotransmitters and involves numerous nerve centers in the brain.
The feeling of satiety occurs during the absorption phase after the food was ingested when nutrients become available in the digestive system.
The feeling of hunger appears in the post-absorption phase.
True anorexia occurs when the animal is not interested in food. This can be a consequence of systemic illness, pain, cancer, neurological disorders, or trauma. Anorexia can also occur as an adverse reaction to certain medications, such as chemotherapeutics or opioids.
Pseudo-anorexia occurs as a result of several factors that do not directly influence the hunger center. The cat is hungry but is unable to eat due to environmental stress (fear, anxiety), diet, breathing problems, swallowing problems, dental problems, pain, etc.
In both types of anorexia nervosa, the cat will lose weight.
4. Dental Issues (Dental Disease)
The most common dental diseases in cats are the accumulation of tartar, periodontitis, and tooth loss. Some cats can also develop stomatitis, a painful inflammation of the mouth and gums.
Most of these conditions cause pain, which can make your cat stop eating, even though it has an appetite. Due to the inability to pick up, chew, or swallow food, the cat will lose weight until it becomes very skinny, or the issue is remediated.
In addition to lack of appetite and weight loss, you may also notice:
- Excessive salivation
- Oral bleeding
- Smelly breath
- Pawing at the face
5. Feline Diabetes
Diabetes is a complex, long-lasting chronic disease. It is caused by improper functioning of the pancreas.
When the pancreas does not function properly, it no longer produces insulin (type I diabetes). In type II diabetes, the body has an inadequate insulin response.
Symptoms of diabetes in cats include:
- Excessive thirst
- Frequent urination
- Vomiting
- Acetone or a fruity breath
- Sudden weight gain (E.g., Your cat may eat 3 times more food than usual)
- Appetite loss
Decreased appetite as an initial symptom is less common as cats tend to gain weight in the first stage and veterinarians actually recommend a weight loss plan.
Significant weight loss often occurs in the final stage of diabetes when the cat is in critical condition. The cat may go into a coma and die if not treated in time.
6. Hyperthyroidism (An Overactive Thyroid)
Hyperthyroidism is characterized by an overproduction of thyroid hormones and an increase in metabolic rate – the daily energy requirement of a resting body.
This disease is common in older cats, but can also occur when there are tumors on the thyroid gland in younger cats.
The symptoms of hyperthyroidism include:
- Loss of appetite
- Weight loss (due to increased metabolic rate)
- Excessive appetite (the cat is always hungry)
- Hyperactivity
- Irascibility
- Aggressivity
- Excessive vocalization (especially at night)
- Excess water intake
- Excessive urination
- Diarrhea
- Vomiting
7. Feline Anxiety
An anxious cat may look strange or funny to its owner at first. It may jump when it hears the doorbell, hide under the bed at the slightest noise, always seems to be on the alert, and so on.
Anxiety can be a medical condition and can occur as a result of stress or fear, or it can be an associated symptom of other illnesses such as ADHD or depression.
Cats can be very sensitive to changes in the home. Because they are excellent at hiding external signs of stress, you may notice severe symptoms later on, but overlook some of the early signs.
Any environmental factor change can lead to anxiety. A cat with a reduced appetite is a common sign of stress and will eventually lead to weight loss.
An anxious cat may show the following clinical signs:
- Decreased or lack of appetite
- Weight loss
- Urinating or defecating outside the litter box
- Vomiting
- Excess vocalization
- Increased time alone
8. Heat Cycle (Aka Hormones)
Heat cycles can begin as early as four or five months in a female cat and are repeated every two to three weeks. If you spay your cat or it gets pregnant, the heat cycle will no longer happen.
It is very easy to notice a cat in heat, especially after the position it adopts – known as lordosis behavior. A female adopts the following position: chest towards the ground, bent legs, raised rear quarters, tail off to the side, and an exposed vulva.
Cats spend a lot of energy during this period and lose weight. Other symptoms encountered in females in heat are:
- Vocalization
- Adopting a mating position
- Discomfort
- Pain
A pregnant cat requires more calories to account for the kitten(s) and excess caloric output due to the pregnancy.
We recommend spaying your cat to improve its health and reduce risks!
9. Inflammatory Bowel Disease (IBD)
The most common form of IBD in cats is the idiopathic form, which unfortunately has no known cause to date. In this condition, inflammatory cells infiltrate the intestinal mucosa.
Cats suffering from IBD are usually middle-aged to older, but even very young cats can be affected.
Affected cats show chronic gastrointestinal signs, such as:
- Anorexia
- Excessive weight loss
- Vomiting
- Diarrhea
- Lethargy
Some cats may have a normal or increased appetite.
The diagnosis cannot be made solely based on the clinical signs, as they are associated with several conditions. For a definite diagnosis, abdominal ultrasound is required.
10. Pancreatitis
In cats, pancreatitis can be acute or chronic. Potential causes of pancreatitis in cats include:
- Liver disease
- Diabetes
- Toxoplasmosis or feline distemper
- Abdominal trauma
- Exposure to insecticides
Pancreatitis can lead to loss of appetite and excessive weight loss. Other clinical signs include:
- Vomiting
- Lethargy
- Abdominal pain
- Dehydration
- Yellow diarrhea or stools
- Decreased body temperature or fever
- Jaundice
11. Gastrointestinal Obstruction
Gastrointestinal obstruction is a blockage of the digestive tract, and food and fluids can no longer pass through it. They can pass partially or not at all.
This can damage the digestive tract and lead to life-threatening consequences for your pet if not dealt with early on.
The causes of gastrointestinal obstruction include:
- Tumors
- Foreign objects (pieces of plastic, wood, fabric, etc.)
- Polyps
- Invagination
- Hernia
Depending on the degree of obstruction (partial or total) and the portion of the digestive tract obstructed, clinical signs may include:
- Vomiting
- Lethargy
- Loss of appetite or refusal to eat
- Excessive weight loss
- Diarrhea
- Abdominal pain or swelling
- Low body temperature
- Vocalization
- The inability to lay down
12. Food Allergies
Food allergies in cats can be expressed at the level of the skin (allergic dermatitis) or can cause gastrointestinal problems.
A cat with food allergies may vomit and have diarrhea. These two symptoms can lead to dehydration and severe weight loss, making a cat look skinny.
13. Cancer
Most cancers can cause a cat to lose too much weight. Weight loss usually occurs suddenly. Cat owners often say that their pet has lost weight in the last few weeks. Other symptoms associated with cancer are:
- Lethargy
- Hiding
- The presence of tumors
14. Lack of Nutrients
Nutrition deficiencies usually occur when your cat eats a poor-quality diet. Poor quality diets may contain insufficient or excess nutrients for your cat’s nutritional needs.
In addition to weight loss, a lack of nutrients can cause a cat to refuse food, be lethargic, vomit, or have diarrhea.
Do not leave your cat without food for more than two days! Cats can develop a liver problem called hepatic lipidosis. This condition leads to liver failure and can be life-threatening if left untreated.
15. Depression
As in the case of anxiety, depression can make a cat no longer want to eat food. Unsurprisingly, this lack of an appetite leads to weight loss.
A depressed cat may:
- Refuse food
- Sleep a lot
- Stare blankly
- Show a decreased interest in activities (playing or going outside)
16. High Levels of Stress
Some cats can be more stressed than others. They can startle at the slightest noise, hide under the couch for hours, or you can rarely see them around the house.
Stress in cats can occur as a result of:
- Bringing another pet into the house
- The arrival of a new member in the family (Newborns, significant other)
- Changing homes
- Car transportation
- Vet appointments (Yes, this stresses some cats out majorly!)
Stressed cats may refuse food and water, or come out of hiding only at night when it is quiet in the house. They may also vomit and behave strangely – more strangely than you’re used to.
17. Kidney Disease
Kidney failure can and often does lead to high levels of weight loss in cats.
This condition is most common in older cats, but can also be congenital. In such cases, the cat’s kidneys no longer function and can no longer filter blood.
Their blood will be full of toxins that can make the cat lose weight, stop urinating, refuse food, be apathetic, and have a strong odor. Cats with advanced renal failure are sadly usually euthanized.
18. Feline Infectious Peritonitis (FIP)
Feline infectious peritonitis is caused by feline coronavirus (CoVF) and is more common in environments with a high density of cats. The disease occurs often in cats less than 1-year-old.
The most prone to infection are stressed cats (adoption, castration, or accommodation in cat shelters). Not all infected cats develop FIP.
FIP in cats has two forms: wet and dry.
- The wet form can cause fluid accumulation in the abdomen or chest, leading to a potbellied appearance or difficulty breathing.
- The dry form can cause appetite loss, weight loss, lethargy, and a fever. As such, if your cat has FIP and is getting skinny, it likely has the dry form.
In addition to the reasons listed above, this YouTube video does a great job highlighting 9 of the top reasons a cat loses weight as well:
Restoration To A Healthy Size: How Can I Help My Cat Gain Weight?
1. Go To Your Veterinarian
It is recommended to talk to your veterinarian whenever you think something is wrong with your cat. At the very least, you should be going one time a year.
If your cat has suddenly lost weight, stopped eating, has difficulty moving, meows excessively, or is lethargic, go to the vet.
They will analyze your cat and then diagnose it. Following the diagnosis, the treatment will be established.
2. Remove Food Competition
Food competition can become a real problem if multiple cats live in your home or you have different types of pets. Shy cats may be left without food and lose weight, while the rest of your pets may gain weight.
Feed your pets separately, at separate hours, or in a separate room. By doing so, you can prevent food competition, and each cat gets its proper share of food.
Chase, the founder of The Cat Insider, used to put one cat in the bathroom with his food while the other was eating their food in the family room. It worked like a charm!
3. Try Different Cat Foods
There are hundreds if not thousands of different types of cat food. You can try feeding your cat other types of food if you see that it is no longer eating its usual food and is starting to lose weight.
You can try wet food or other dry food brands. If your cat only eats dry food, you can mix a little wet food with its regular meal or vice versa.
Try several foods until you find one your cat likes! But be sure to slowly transition from brand to brand. It can take cats some time to acclimate to new foods.
4. Try Different Temperatures For Cat Food
For cats that no longer eat and start to lose weight, you can try heating the food a little before serving it.
- If your cat only eats dry food. Heat some water, tuna juice, or broth and add it to its kibble. Let it sit for 5 minutes so that the dry food can absorb some of the liquid.
- If your cat only eats wet food. Mildly heat the food and serve it to your cat – room temperature or slightly over is best. Start small, and add more heat as needed. Do not confuse heat for spices here. We mean literally heating a bowl of food via the microwave or putting a can of food in a bowl of warm water prior to serving.
Be careful not to overheat it! Test the temperature on the back of your hand.
5. Feed Your Cat Smaller Portions of Food More Frequently
Cats can eat anywhere from 1-to-10 meals a day on average. Wild cats generally eat more often than domesticated cats as they need to pounce when the opportunity presents itself.
It is not always obvious how much you should feed your cat, so cat food manufacturers detail on the package the general guidelines for cat owners. Our post on how much to feed a cat can help you better understand how much food your cat should be consuming based on their age, health status, and other factors.
Remember that they are showing you recommendations, but every cat is different. Chances are your cat may be more active than the average cat, requiring additional calories to maintain a healthy weight. So don’t be afraid to try providing more food to see if it helps with weight gain.
6. Develop A Relaxing Environment At Home
This remedy works for all cats but is especially recommended for those suffering from stress, anxiety, or depression.
There are many kinds of products that can help your pet relax, from cat music to pheromone diffusers. A cat that feels relaxed and at ease will more likely have healthy, consistent eating habits.
Final Thoughts On Underweight Cats and Steps We Can Take To Help
It can be extremely concerning if your cat is losing weight and you don’t know why. Remember that your veterinarian is your best advocate for your cat, and will better understand them. We always recommend going to the vet before attempting any remedies at home.
It is always better to prevent than to treat. Take your cat to the vet for a complete set of tests at least once a year. For cats that are known to suffer from certain conditions or senior cats, it is recommended to do it twice a year or on a schedule your vet recommends.
But don’t let the stress of the events keep you from showing your cat love and care. Always remember that your cat is a part of your world, but you’re their entire world. Be patient with their symptoms, show them relentless love and affection, and throw them a few extra treats!