Why Is My Cat So Skinny?

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As a proud cat owner, I often see new cat owners wondering: “Why is my cat so skinny?”

The most straightforward answer is: It is difficult to tell why your cat looks skinny by just looking. 

There could be several reasons your cat is too slim — ranging from inadequate food to underlying health issues.

In this article, I’ll cover the following topics:

Reasons Why Your Cat is So Skinny

There are many possible reasons why your cat is so skinny. However, we want only to focus on the most probable ones.

Not Enough Food

Getting skinny occurs when your cat consumes too few calories than it burns. Your cat might too thin because it’s not be eating enough to maintain a healthy body weight. 

Some of the reasons why your food intake might not be enough include:

  • Food competition at the bowl with other cats or a sneaky dog if she’s living in a multi-pet household
  • Dental disease or pain in the mouth
  • Anxiety or stress due to environmental changes or the introduction of a new human into their lives
  • Disinterest in the type of food you’re serving it

When your cat doesn’t eat enough, it’ll start losing weight because it uses its fat reserve to provide energy. If your cat doesn’t have enough fat reserve, the body will break down muscle tissue to provide energy. The muscles loss will induce weight loss and bony, slim appearance.

Digestive Tract Issues

Digestive tract issues can interrupt normal digestion and food absorption, inducing drastic weight loss. Your cat’s digestive tract breaks down food, extracts nutrients, and eliminates waste. When the gut system has defect, it can cause:

  • Impaired nutrient absorption: Digestive problems such as inflammatory bowel disease (IBD), parasites, food allergies, and pancreatitis can damage the lining of the intestine. The damage reduces the surface area available for nutrient absorption. As a result, even if your cat is eating, it might not absorb enough nutrients to maintain a healthy weight.
  • Inability to break down nutrients: Conditions like pancreatitis can lead to a lack of digestive enzymes necessary for nutrient breakdown. Without the right enzyme, your cat’s body may not be able to effectively absorb nutrients from food resulting in nutrient deficiencies and weight loss.
  • Diarrhea and fluid loss: Tummy issues can cause diarrhea, which leads to bodily fluid loss. Water loss can lead to dehydration and electrolyte imbalances, contributing to weight loss.

If you suspect your cat is getting skinny because of digestive tract issues, consult your vet.

The vet will perform a diagnostic test to identify the problem and administer an appropriate treatment plan.


Most old cats develop hyperthyroidism. The defect can cause your cat’s thyroid glands to produce an excess of thyroid hormone. Excess thyroid hormone causes:

  • Increased metabolism: The thyroid hormone’s main function is regulating the body’s metabolism. When in excess, the thyroid hormone increases metabolic rate forcing your cat to burn more calories, leading to weight loss.
  • Muscle wasting: If your cat’s source of calories is limited, the excess thyroid hormone will force the body to break down muscle tissues as an energy source. As the muscle mass of your cat reduces, it will look skinny.
  • Caloric demand exceeds intake: The increased metabolic rate caused by hyperthyroidism can create a situation where your cat’s body requires more calories than it can take in through food. This can lead to a negative calorie balance, where the body uses up more calories than it’s getting from the diet, resulting in weight loss.

While hyperthyroidism has various symptoms, the common one is weight loss.

Organ Failure

Organ failure, such as kidney or liver failure, could be the reason for your cat’s weight loss and skinny appearance. Organs are critical in maintaining overall health, and when they fail, they can affect  various body functions such as:

  • Metabolism
  • Digestion
  • Nutrient absorption

Kidney Failure

When your cat’s kidney fails, it won’t effectively filter waste products and toxins from the blood. The substances will accumulate in your cat’s body, leading to nausea, loss of appetite, and general discomfort, reducing your cat’s food intake and reducing weight loss.

Liver Failure

The liver involves numerous metabolic processes. When it fails, the processes can be disrupted, leading to changes in how the body uses and store energy, which can contribute to weight loss.

Besides, your cat’s liver produces important salts to digest proteins necessary for various functions. Liver failure can impair protein digestion, affecting muscle maintenance and overall body condition.

Diabetes Mellitus

A diabetic kitty often appears thin despite a voracious appetite. The problem is that the cat can’t properly process and utilize the calories it consumes due to insufficient insulin production or the body’s inability to regulate blood sugar.

When a cat has diabetes mellitus, it can show several effects that can induce weight loss, such as:

  • Insufficient glucose utilization: A kitty with diabetes mellitus has difficulty taking in glucose, the primary energy source. This can lead to a situation where your cat’s cells are starving for energy even though glucose is available in the bloodstream. As a result, your feline friend starts breaking down fat and muscle tissues to use as alternative energy sources, leading to weight loss and muscle wasting.
  • Chronic hunger: Despite the high glucose levels in the blood, diabetic cat cells don’t get enough energy. This triggers hunger feeling and increased appetite. While your cat may be eating more, the inability of the cells to use glucose effectively means that the weight loss continues.
  • Glucose loss through urine: Diabetes mellitus causes excess glucose in the bloodstream to spill into the urine. The spill can increase urination because the body is trying to eliminate excess glucose. The increased urination contributes to dehydration, which can further contribute to weight loss.

Untreated diabetes can have other serious consequences for your cat’s health.


Benign or malignant tumors are a notorious cause of weight loss in cats. Cancer cells consume lots of calories, robbing your cat of the nutrition it requires.

The cancer cells compete with your cat’s normal cells for nutrients. As a result, healthy tissues may not receive enough nutrients to function properly, leading to weight loss and general weakness.

Some tumors can produce substances that affect appetite-regulating function in your cat’s body.  The substances may suppress your kitty’s appetite, making your cat consume fewer calories and lose weight.

What Can You Do When Your Cat is So Skinny?

The first step to remedy weight loss is to find out why your cat is losing weight. Then from there, you’ll decide on a plan of action that includes a diet to help your feline friend safely gain healthy weight.

After addressing the underlying healthy issues, select the right food, and figure out how much to feed your cat for weight gain. Some tips for getting your cat to eat reliably and gain weight safely include:

  • Rule out medical conditions that might be making your cat so thin
  • Examine and improve the quality of your cat’s diet
  • Get your cat fresh or wet food instead of dry food
  • Increase your cat’s portion gradually
  • Feed small frequent meals instead of two smaller meals
  • Offer healthy snacks between meals 
  • Consult your vet about appetite-stimulating medicine
  • Serve warm food to entice your cat with an aroma to eat

Your feline friend can remove the skinny status with proper dietary habits, regular checkups, and routine pampering.


Why is my cat so skinny but eats?

Your cat can be skinny but eats for several reasons, including:
Digestive issues
Consult a vet to identify the underlying cause.

How do you fatten up a skinny cat?

Fattening a skinny cat requires you to identify the underlying cause of weight loss. After ruling out medical issues, you can gradually increase high-quality calorie-dense food.

Is it normal for a cat to be very skinny?

No. It isn’t normal if your cat has sudden weight loss. Cats should maintain a healthy weight for their size and breed.

Is my cat too skinny if I can feel her spine?

Feeling the spine is normal for most cats. But a prominent spine may indicate weight loss or other issues.

Why is my cat so skinny all of a sudden?

Sudden weight loss can be due to various factors, such as illness, stress, or dietary changes.
Consult your vet if your cat is losing weight drastically.

How do I know if my cat is too skinny?

You cat tell your cat is skinny by feeling their ribs and spine. If they’re too prominent, your cat might be underweight. Consult your vet for an accurate assessment.

About Laura Martin

I'm Laura Martin. I get excited about all things cat related. I love my two cats - Dom and Kitty. When I'm not playing with my two feline friends, you can probably find me hiking. And yes, I have a 9 to 5 job. Although if you asked me I'd rather spend my time blogging and educating other cat moms and dads about what it takes to raise a healthy cat.

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