Is My Cat Overweight? Causes & Consequences

Almost every second cat is considered overweight. Overweight and obesity are not to be trifled with: Both of these not only impair the quality of life and life expectancy of cats but also increase the risk of diseases such as diabetes or joint pain. You can find out how to tell if your cat is overweight here.

When is My Cat Overweight?

To be able to judge whether a cat is overweight, it helps first to take a look at the normal weight of cats. With a few exceptions, many cat breeds have a comparable height and ideal weight.
If the bodyweight is now ten percent above the ideal weight, one speaks of being overweight. A cat, on the other hand, suffers from obesity if it is twenty percent or more above its normal weight.

Of course, in every breed or mixture of several breeds, there are individual males and females that are more delicate or heavier. The above classification is only an approximate guideline that you as the owner can use as a guide. Ultimately, each cat must be assessed individually to determine whether it is overweight.

Tip: A possible orientation aid for being overweight is, in addition to the weight classes, also the bodyweight at the end of the first year of life.

How Do I Know if My Cat is Overweight?

There are several ways to tell if your cat is overweight or not. The most frequently used – and at the same time, probably the most objective method – for an initial assessment is the assessment of the nutritional status.

This can be determined using the Body Condition Score (BCS, body condition index). The BCS is based on the visual assessment and palpation of body fat on the chest, waist, and spine. Based on the observations, the cat is then classified into one of nine BCS classes.

In general, a cat is considered too fat when the ribs can no longer be felt and the waist can no longer be seen. When viewed from the side, the lower belly line should rise slightly from the ribs to the hips and not (almost) parallel to the floor. Fat pads in the lumbar region are another sign of an overweight cat.

By weighing your cat regularly, you can also see if the weight of your furry nose has changed. If the scales show a higher weight each time, it is very likely that your darling is slowly getting bigger and bigger.

The Body Mass Index for the Cat (FBMI)

Another method for the simple determination of obesity is the Feline BMI (Feline Body Mass Index, FBMI) developed for cats. Percentages of ten to 30 percent are considered normal in cats using this method. If the values are above 30 percent, then that speaks for overweight or obesity.

To calculate the FBMI you need two values: the chest circumference in centimeters and the leg index measurement (LIM, distance between the kneecap and the heel bone in centimeters).

How Do Cats Gain Weight?

The cause of obesity in cats is always an imbalance between energy intake and energy consumption. As simple as this explanation sounds at first, obesity in cats usually arises when various factors interact. That is why it is so important to prevent it from occurring at an early stage.

Often the path to later obesity already begins in the kitten age. Because feeding that is too high in energy results in a larger number of fat cells than in normally nourished kittens. This number cannot be changed later so that there is a higher risk of obesity in adulthood.

Main cause 1: Too much energy supply

If a cat becomes overweight, consuming too much energy is one of the most common triggers for weight gain. Cats find it difficult to compensate for this excess energy through movement, as they usually (can) only move a little when they are kept in an apartment.

The most common causes of an energy surplus: The amount of feed is too large, there is unrestricted access to the feed (ad libitum feeding), and/or the feed has too high an energy density (too many calories calculated on the portion).

The dry food that is often used in ad libitum feeding, for example, has an energy density that is five times higher than that of wet food per 100 grams. If cats are fed dry food alone, they tend to consume more calories per day than they need.

Cats also tend to eat very tasty food such as fresh meat and fish, as well as food with high-fat content. Food from the table, in particular, is often high in fat. The problem here is that fat contains twice as much energy as protein or carbohydrates.

In addition, fur noses like to eat out of boredom or when they are under constant stress. In addition, cats often show begging behavior, especially when they are bored. Owners often mistakenly interpret this as a sign of hunger and re-feed their cat.

In addition, when feeding, cat owners tend to forget that treats also contain a lot of calories. They must therefore be taken into account in the daily ratio.

Main cause 2: Low energy consumption

In principle, a young cat (under two years of age) has a higher energy requirement than adult or old cats. However, the energy requirements of the individual cat can be very different.

This makes an accurate estimate of the amount of feed required difficult. Often the feeding behavior and the amount of food are not adapted to changing needs and the cat gains weight.

Additionally, an overweight cat needs fewer calories per kilogram (forty-four kilocalories per kilogram) than normal weight (fifty-six kilocalories per kilogram) or a very light cat (sixty-three kilocalories per kilogram). This must be taken into account, especially when dieting for weight loss.

Main cause 3: The castration

Another trigger for a cat to become overweight is neutering. A neutered cat tends to have increased appetite, decreased physical activity, and changes in body fat percentage. This reduces the energy requirement of a cat after neutering by up to thirty percent. If the amount of food is not reduced, neutered cats are three times as likely to become overweight as non-neutered cats.

Diseases as a Trigger for Weight Gain

In addition to all the causes that can be influenced by the environment and the owner, it is imperative to first rule out possible diseases as a causative agent of an overweight cat. Please clarify this with your veterinarian.

The following diseases can cause the cat to gain weight:

  • Cushing’s disease (hyperadrenocorticism)

Cushing’s disease is a disease of the adrenal cortex. The adrenal gland permanently produces too much cortisol. This leads to an increased appetite, at the same time the cats become reluctant to move and become sluggish. Both symptoms lead to fat deposits, due to the disease, especially in the abdomen. They have a big, drooping stomach, while the rest of the body is often very slim.

  • Acromegaly / hypersomatotropism:

The hormonal disorder is caused by an enlargement or a tumor of the pituitary gland (pituitary gland). This produces more growth hormones. The excess supply of growth hormones enlarges bones, internal organs, and connective tissue. In cats, this can be recognized by their relatively large and broad head and paws that are getting bigger and bigger. In addition, growth hormone causes insulin resistance in almost all cases and thus secondary type II diabetes, which is difficult to control with insulin. There is an increased appetite and, as a result, further weight gain.

  • Underactive thyroid (hypothyroidism)

This disease results in insufficient production of thyroid hormones. These are responsible for the cell function and thus the cat’s metabolism. Due to the lack of hormones, the cells work too slowly and no longer use as much energy. In addition, a sick cat will become sluggish and move less. Hypothyroidism is extremely rare in cats.

In addition to hormonal diseases, there are other diseases that can indirectly lead to weight gain through greatly reduced physical activity. Unfortunately, being overweight makes these diseases more likely, which is why the cat is in a vicious circle here. For example, cardiovascular problems and respiratory diseases lead to fatigue and poor performance.

If the cat has a history of osteoarthritis or arthritis, the pain does not mean that the cat wants to move a lot. Unfortunately, the owner often does not notice that his cat has problems with its joints.


For some diseases, drugs are necessary that lead to an increased appetite and thus secondary weight gain. First and foremost, antiepileptic drugs, glucocorticoids, and progestogens (drugs to suppress heat) should be mentioned here.

Consequences if the Cat is Overweight

Obesity is to be seen as a disease that inevitably leads to further diseases. Overweight cats have a shorter life expectancy than normal-weight cats of the same breed due to the consequential damage and diseases.

Diabetes mellitus and glucose intolerance

Obesity is one of the biggest risk factors in cats for diabetes mellitus. This is type II diabetes caused by insulin resistance. The body still produces enough insulin, but this no longer has any effect on the metabolism.

Diabetic cats often have food cravings and are tired and sluggish at the same time. This further promotes weight gain. Type II diabetes mellitus can be improved or disappear entirely through a strict diet and weight reduction.

Idiopathic hepatic lipidosis

The fatty liver syndrome occurs when cats, especially overweight cats, hardly eat anymore or not at all. The metabolism then mobilizes (releases) fats from the fat stores.

Cats cannot use these fats for energy production and the fats are stored in the liver cells. The liver can no longer function normally and liver failure occurs.

An overweight cat that hardly or no longer eats for several days must be presented to a veterinarian. If hepatic lipidosis occurs, this is a life-threatening condition that requires intensive medical care.

Joint and movement disorders

Being overweight leads to often underestimated problems with the musculoskeletal system in cats.

In adult cats that are overweight, the increased weight leads to overuse of the joints and ligaments. The possible consequences are arthritis and arthrosis, especially in the area of the elbow and hip joints.

With joint pain, cats are more likely to show reduced physical activity and longer rest periods. On the other hand, the owner rarely sees significant lameness or expressions of pain, which is why joint diseases are often overlooked.

If a cat is overweight, its body also produces more inflammatory mediators, which in turn can contribute to the progression of arthritis. The consequence of this joint pain is a reduced enjoyment of movement and thus, due to the lower energy consumption, further weight gain.

Lack of grooming

Many overweight cats have skin problems. If a cat is overweight, its mobility is significantly restricted. As a result, she may no longer be able to carry out her usual grooming and body care adequately. This leads to increased dandruff formation all over the body and often also to stool contamination.

The lack of hygiene can lead to feline acne, coat loss, and skin inflammation. A high degree of obesity with an almost complete lack of movement also often results in pressure necrosis (areas of skin that are dead and severely inflamed due to excessive pressure).

Lower Urinary Tract Disorders (FLUTD)

An overweight cat will exercise less, drink less, and use the litter box less often. This means that the urine stays longer in the bladder and becomes more concentrated.

Urine crystals can form more easily and the risk of the urinary stone formation increases significantly. Urinary stones lead to chronic bladder infections and can cause acute occlusion of the urethra. The latter is always an emergency!

An overweight cat with stomach and intestinal problems

Studies show a connection between obesity in cats and the increased incidence of diarrheal diseases, IBD (Inflammatory Bowel Disease), diseases of the anal sacs, and constipation (constipation).

These diseases are not triggered directly by being overweight but are mostly, in turn, the consequences of diseases that result from obesity. For example, a sedentary lifestyle can lead to indigestion and constipation.

Lung problems

The larger body mass of overweight cats leads to a higher need for oxygen. In addition, there is fat storage in the chest cavity. The cramped breathing space and the higher demand for oxygen cause breathing problems and shortness of breath. The cats have poor stamina and tire more quickly.

The cat does not want to move so much and continues to increase due to the lower energy consumption.

Cardiovascular problems

Obesity in cats is involved in the development or at least in the progression of heart disease. High blood pressure is also one of the negative effects.

In an overweight cat, the excess energy is stored as fat throughout the body. This fat is also deposited infiltratively (penetrating into the tissue) in organs such as the heart or the liver.

The problem: This storage restricts the heart in its performance. In addition, however, it has to supply a larger body mass with blood and work against greater pressure in the vessels. All of this leads to heart damage and heart failure in the long term.

Higher anesthetic drug consumption and poor wound healing

Adipose tissue stores the anesthetics and therefore requires a larger amount. At the same time, the breakdown of drugs in the liver and their elimination via the kidneys is impaired. Together with the often impaired lung function and cardiovascular problems, an overweight cat is considered a risk patient.

The reduced blood flow in the entire body tissue also increases the risk of wound infections and wound healing disorders during operations.

Bad immune system and increased tumor diseases

If a cat is overweight, it has a reduced immune system. It is, therefore, more prone to infections and other diseases. In addition, animals that are too heavy are often more sensitive to heat.

Too much bodyweight also affects fertility. Pregnancy in the female is fraught with greater risks and the birth path, which is narrowed by fat deposits, makes childbirth more difficult.

Tumor diseases are also much more common in overweight cats. For example, there appears to be a connection between obesity and adenocarcinoma, lymphoma, or squamous cell carcinoma.

Mary Allen

Written by Mary Allen

Hello, I'm Mary! I've cared for many pet species including dogs, cats, guinea pigs, fish, and bearded dragons. I also have ten pets of my own currently. I've written many topics in this space including how-tos, informational articles, care guides, breed guides, and more.

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