Why Is My Cat Skinny?

sad grey tabby cat

As responsible cat owners, we strive to provide our pets with the best care possible. So, when we notice that our cat is looking skinny or losing weight, it’s only natural to feel concerned and wonder, “Why is my cat skinny?”

While some cats naturally have a slender build, unexplained weight loss can be a sign of underlying health issues that require attention. Medical conditions like hyperthyroidism, kidney disease, and cancer can cause weight loss, as can parasites, stress, dental problems, and gastrointestinal disorders.

Early detection and intervention are key in addressing feline weight loss. By understanding the underlying causes, you’ll be better equipped to recognize the signs, seek timely veterinary care, and provide the necessary interventions to help your cat regain a healthy weight.

So, let’s dive into the fascinating world of feline health and uncover the reasons behind your cat’s thin appearance.

Why A Healthy Weight Is Important For Cats

Cats need to maintain a healthy weight just like humans, as being overweight or underweight can cause health issues and lower their quality of life (see our article “Is My Cat Overweight” for information on fat cats).

Cats that maintain a healthy weight are less likely to experience chronic health issues such as diabetes, heart disease, arthritis, and respiratory problems. Moreover, they have a more robust immune system, which enables them to combat illnesses more effectively.

Maintaining a healthy weight can increase a cat’s chances of living a longer and healthier life. Regular veterinary check-ups, a balanced diet, and regular exercise are key factors for keeping your cat at a healthy weight.

When Is A Cat Considered Skinny?

A cat is generally considered skinny when its body condition indicates a lack of adequate body fat and muscle mass. While individual cats may have variations in body size and shape, there are some general things to look for to help determine if a cat is skinny:

  1. Visible ribs and spine: When looking at a cat from the side, you should be able to feel its ribs with your fingertips but should not be able to see them through its fur and skin. Similarly, the spine should be felt but not visibly protruding.
  2. Obvious waistline: When viewing the cat from above, a cat that is not overweight will have a visible waistline behind the rib cage. But if the area appears excessively narrow or the abdomen looks sunken, it may suggest that the cat is underweight.
  3. Lack of muscle definition: Healthy cats typically have well-defined muscles, particularly in the shoulders, hips, and thighs. If a cat lacks muscle tone and appears bony or frail, it may be an indication of being too skinny.
  4. Overall body shape: A cat at a healthy weight has a balanced body shape, with a proportional head, neck, and body. If the cat appears to have a disproportionately small body compared to its head or has a gaunt, skeletal appearance, it could signify that the cat is skinny.

We recommend checking out our explanation of cat body condition scores for more information on what to look for.

It’s important to consider factors such as the cat’s breed, age, and individual metabolism when assessing its body condition. Young cats and some breeds naturally have a leaner build, while older cats may lose some muscle mass with age.

However, significant weight loss, prominent bones, a lack of muscle tone, and a visibly skinny appearance are indicators that a cat is skinny. Cats that are too skinny or those who have had rapid weight loss need veterinary medical attention.

Potential Reasons Why Your Cat Is Skinny

There are several common reasons why your cat may lose weight, such as medical issues like hyperthyroidism and chronic kidney disease, parasitic infestations, stress, and dental disease. To better understand how each of these factors can impact weight loss in cats, let’s take a closer look.

Medical Conditions


Hyperthyroidism is a common endocrine disorder in cats that results from an overactive thyroid gland. The thyroid gland produces an excess amount of thyroid hormones, primarily thyroxine (T4).

The elevated thyroid hormones speed up the cat’s metabolism, causing them to burn calories rapidly. As a result, the cat’s body utilizes its fat stores and muscle mass for energy, leading to gradual weight loss over time.

The increased metabolic rate also creates an increased demand for nutrients, which further contributes to weight loss despite a seemingly ravenous appetite.

Chronic kidney disease

Chronic kidney disease (CKD) is a progressive and irreversible condition that affects the kidneys’ ability to function properly. It is a common condition in older cats and some breeds such as Persians.

One of the primary reasons why cats with CKD experience weight loss is due to the loss of muscle mass. The kidneys play a crucial role in protein metabolism, and when they are compromised, protein metabolism is impaired. This leads to muscle wasting and weight loss in affected cats.

Additionally, cats with CKD often have reduced appetite and may experience nausea or gastrointestinal disturbances, which can further contribute to weight loss. As the disease progresses, cats may also become dehydrated, exacerbating their weight loss.

The combination of muscle wasting, reduced appetite, and fluid imbalances associated with CKD can significantly impact a cat’s body weight, leading to gradual weight loss over time.


In many cases, unexplained weight loss is the first indication that cancer may be present. Overall, cancer-related weight loss in cats is multifactorial, involving metabolic changes, altered appetite, tissue breakdown, and nutrient imbalances.

The presence of tumors can disrupt normal body processes, leading to metabolic changes and nutrient imbalances. Additionally, cancer cells consume a significant amount of energy, diverting nutrients away from normal bodily functions.

Cancer-associated weight loss, known as cancer cachexia, involves a complex interplay of factors. Tumors release substances called cytokines that can increase metabolism and decrease appetite. These cytokines also contribute to the breakdown of muscle and fat tissues, leading to muscle wasting and weight loss.

Furthermore, cancer can interfere with the digestive process, impairing nutrient absorption and utilization. This can result in malnutrition and further exacerbate weight loss in affected cats. The location and type of cancer can also impact food intake and the body’s ability to derive energy from nutrients.

Gastrointestinal disorders

Conditions that disrupt normal digestion and nutrient absorption in the gut can lead to weight loss in cats. These disorders can include conditions such as inflammatory bowel disease (IBD), pancreatitis, or gastrointestinal infections.

Inflammatory bowel disease, for instance, causes chronic inflammation of the gastrointestinal tract, impairing the cat’s ability to properly digest and absorb nutrients from food. This can result in malabsorption of essential nutrients, leading to weight loss despite adequate caloric intake.

Pancreatitis, an inflammation of the pancreas, can also disrupt the digestive process. The pancreas produces enzymes that aid in food digestion, and when inflamed, it may not produce enough enzymes, leading to poor nutrient absorption and subsequent weight loss.

Gastrointestinal infections can also cause inflammation and disrupt the normal functioning of the digestive system. Additionally, gastrointestinal disorders can be accompanied by symptoms like vomiting, diarrhea, or decreased appetite, further contributing to weight loss in affected cats.


Parasites in cats, such as intestinal worms (e.g., roundworms, hookworms) or external parasites (e.g., fleas, ticks), can contribute to weight loss by affecting the cat’s overall health and nutrient absorption.

Intestinal worms compete with the cat for nutrients from the food they consume. They attach themselves to the intestinal lining, absorbing nutrients intended for the cat’s nourishment. This competition for nutrients can lead to malnutrition and subsequent weight loss.

Furthermore, the presence of worms can cause irritation and inflammation in the gastrointestinal tract, leading to symptoms such as diarrhea, vomiting, and decreased appetite. These symptoms can further contribute to weight loss.

External parasites like fleas and ticks can also lead to weight loss indirectly. These parasites feed on the cat’s blood, causing discomfort, itching, and potential blood loss. The continuous blood loss, though often small, can add up over time and contribute to anemia and weight loss.

Dental problems

Dental problems in cats can contribute to weight loss by making it painful or difficult for them to eat. Conditions such as periodontal disease, tooth decay, or oral infections can cause discomfort and inflammation in the mouth, leading to a decreased appetite and avoidance of food.

Cats with dental issues may experience pain while chewing, resulting in a reluctance to eat or a preference for softer foods. This can lead to a reduced caloric intake and subsequent weight loss over time.

Additionally, cats may develop oral sores or infections, further deterring them from consuming food. As a result of dental pain and reduced food intake, cats may not be able to consume enough nutrients to maintain a healthy weight.


When a cat is stressed, it may experience a decrease in appetite or even develop an aversion to food. Stress hormones, such as cortisol, can suppress the cat’s appetite and disrupt normal eating patterns. This can result in a reduced caloric intake and, over time, lead to weight loss.

Chronic stress also affects the cat’s overall well-being, leading to behavioral changes, anxiety, or depression. Cats that are chronically stressed may exhibit decreased interest in food or engage in behaviors that interfere with normal eating patterns.

Stress can impact the cat’s digestive system, leading to gastrointestinal disturbances such as diarrhea or vomiting. These symptoms can contribute to nutrient malabsorption and further exacerbate weight loss.

When Should I Be Worried About My Cat’s Weight Loss?

Physical changes

When it comes to a cat’s weight loss, there are certain physiological changes that should raise concerns and warrant immediate attention. These changes indicate that the weight loss is significant and may be indicative of an underlying health issue. Here are some physiologic changes to watch for:

  • Visible bones: If your cat’s ribs, spine, or hip bones become prominently visible or easily felt with minimal pressure, it suggests significant weight loss. The loss of body fat and muscle mass can cause these skeletal structures to become more pronounced, indicating a concerning level of weight loss.
  • Sunken appearance: A cat with a healthy weight should have a well-rounded and proportionate body shape. If you notice a sunken or concave appearance in the abdomen, it may suggest excessive weight loss.
  • Lack of muscle tone: Healthy cats have good muscle tone, particularly in the shoulders, hips, and thighs. However, significant weight loss can lead to muscle wasting, resulting in a lack of muscle definition. The loss of muscle tone is a sign that the cat’s weight loss may have reached an alarming level.
  • Dull or unkempt coat: Weight loss and poor nutrition can impact a cat’s coat quality. If your cat’s fur becomes dull, brittle, or lacks its usual luster, it may be an indication that their weight loss is affecting their overall health.
  • Lethargy or weakness: Rapid or significant weight loss can cause cats to become lethargic and weak. They may exhibit reduced energy levels, reluctance to play or engage in activities, and overall diminished stamina.

If you observe these physical changes in your cat, it is essential to consult with a veterinarian promptly. Significant weight loss can be a sign of an underlying health condition that requires diagnosis and treatment.

black and white photo of a skinny cat

Behavioral changes

Behavioral changes accompanying weight loss in cats can provide additional insights into their overall health and well-being. Paying attention to these behavioral changes is important as they may indicate underlying issues contributing to weight loss.

Here are some behavioral changes to be concerned about:

  • Decreased appetite: A significant decrease in appetite or lack of interest in food can be a red flag for weight loss. A sudden or prolonged loss of appetite may indicate an underlying health problem or discomfort that needs to be addressed.
  • Changes in eating habits: Cats typically have consistent eating habits. If you notice a change in your cat’s eating behavior, such as eating significantly less, taking longer to finish meals, or displaying aversions to certain foods, it may suggest a problem.
  • Increased water consumption: While increased water intake can be a sign of certain medical conditions, it can also be linked to weight loss. Diseases such as diabetes or kidney problems can cause excessive thirst, leading to increased water consumption.
  • Litter box changes: Weight loss can affect a cat’s litter box habits. Increased frequency of urination or changes in stool consistency (e.g., diarrhea) may indicate an underlying health condition contributing to weight loss.
  • Changes in activity levels: Cats experiencing weight loss may display decreased energy and reduced activity levels. If your typically active cat becomes lethargic, avoids playtime, or shows reluctance to engage in physical activities, it could be a sign of an underlying issue causing weight loss.

Rapid Weight Loss

Any rapid weight loss is cause for alarm in cats because it often leads to feline hepatic lipidosis (fatty liver disease).

Fatty liver disease occurs when the body breaks down fat stores for energy at an excessively rapid rate, overwhelming the liver’s capacity to process and metabolize the fat. Here’s why you should be concerned about this condition:

  • Liver dysfunction: Fatty liver disease can lead to severe liver dysfunction and compromise the liver’s ability to perform its vital functions. The liver is responsible for detoxification, metabolism, and the production of essential proteins. When the liver becomes overwhelmed with excessive fat, it can’t function properly, leading to a cascade of health problems.
  • Nutritional imbalances: In cats, prolonged fasting or inadequate caloric intake triggers the body to mobilize fat stores for energy. However, cats have a unique metabolic process that can lead to a buildup of fat in the liver if fat breakdown occurs too quickly.
  • Progressive nature: Fatty liver disease can worsen rapidly if left untreated. As the liver’s functionality declines, the condition can become self-perpetuating. The liver’s impaired ability to process fat exacerbates the accumulation of fat, creating a vicious cycle. If not addressed promptly, fatty liver disease can become life-threatening.

Cats with fatty liver disease may show signs such as jaundice (yellowing of the skin and eyes), lethargy, vomiting, loss of appetite, and dehydration.

If left untreated, the condition can lead to complications such as hepatic encephalopathy (brain dysfunction due to liver failure), severe electrolyte imbalances, and organ failure.

Fatty liver disease requires prompt and aggressive treatment to reverse the condition. Cats with fatty liver disease often require supportive care, nutritional support through feeding tubes, and close monitoring.

Treatment can be challenging and often involves a comprehensive approach to address the underlying cause, restore liver function, and provide adequate nutrition.

How To Help A Cat Gain Weight

When I adopted my Sphynx rescue cat, she was very skinny. Her body condition score was 2, at best. Besides trying to earn her trust and reduce her fear and anxiety, my primary concern was helping her to gain weight. But how does one go about doing that?

The first thing that anyone must do is address the underlying problem – whatever it is that’s causing the weight loss. Whether it be a medical condition or simply not eating enough, the cause must be determined before a plan of action can be put in place.

Cats that are too skinny should be examined by a veterinarian to ensure that there are no underlying medical issues. If a medical problem or parasite infestation is ruled out, then the next step would be to feed them more calories. Your veterinarian will help you figure out the best course of action for your cat.

In the case of my Sphynx cat, weight gain was achieved gradually by feeding a high-calorie diet meant for nursing mothers. Nursing mother foods are some of the highest calorie foods that are commercially available for cats.

I fed the nursing mother diet as free-choice dry kibble plus a half a can of wet food twice a day. It took about four months before she reached her ideal weight.

If your cat is not eating enough, you can try the following techniques to encourage increased food intake:

  • Offer a variety of food options: Experiment with different flavors, textures, and brands of cat food to find what your cat prefers. Some cats may have particular preferences or aversions, so finding the right food can stimulate their appetite.
  • Warm the food: Heating the food slightly can enhance its aroma and make it more enticing to your cat. However, ensure that the food is not too hot to avoid burning their mouth.
  • Hand-feeding: Some cats respond well to being hand-fed. Gently offer small portions of food from your hand to entice your cat to eat. This close interaction can help build trust and create positive associations with mealtime.
  • Try wet or moist food: Wet or moist cat food has a higher water content, which can be more appealing to cats. The added moisture can also help with hydration and overall digestion.
  • Add tasty toppers: Sprinkle a small amount of low-sodium broth, tuna water, or a commercially available food topper on your cat’s food. These flavorful additions can make the meal more enticing and encourage your cat to eat more.
  • Feed smaller, frequent meals: If your cat struggles to eat larger meals, try feeding smaller, more frequent meals throughout the day. This approach can help prevent them from becoming overwhelmed and aid in better digestion.
  • Monitor feeding environment: Ensure that your cat has a quiet and peaceful space to eat. Some cats may feel stressed or anxious if they are eating in a busy or noisy area. Providing a calm environment can help them feel more relaxed and focused on their food.

When switching to a new food, new treats or food toppers, always remember that all food transitions need to be done gradually over a week or two to avoid digestive upset. Gradual transitions allow your cat to adjust to the new food while maintaining their interest in eating.

Remember, patience is key when helping a cat gain weight. It may take time to find the right approach for your cat.


In summary, if you find your cat to be skinny, it’s essential to address the issue promptly to ensure their health and well-being.

Understanding the potential reasons behind their weight loss can guide you in finding the appropriate solutions. Whether it’s providing a balanced diet, seeking veterinary advice, or addressing behavioral and environmental factors, taking a proactive approach is crucial.

Remember, weight loss in cats should never be ignored, as it can have serious consequences on their overall health. By being attentive to their nutritional needs, monitoring any changes in behavior or physique, and seeking professional guidance, you can help your cat regain a healthy weight and improve their quality of life.

Disclaimer: This article is intended for information purposes only, and does not constitute medical advice. Always consult your veterinarian if you have specific concerns about your pet’s health.


  • Dr. Wendy Wilkins, DVM, PhD

    Dr. Wendy Wilkins is an experienced veterinarian and epidemiologist with over 20 years of expertise. She holds a Doctor of Veterinary Medicine (DVM) degree and a Doctorate in Epidemiology from the University of Saskatchewan. Throughout her career, Dr. Wilkins has excelled in clinical practice, academia, research, and regulatory veterinary medicine. She is a respected voice in knowledge dissemination, delivering factual information in a readable and understandable manner through articles, books, and public engagements.

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