Obesity is becoming as much a problem in pets as it is in humans, with an estimated huge 39-52% of cats in the U.K. being classed as overweight. When we think of poor nutrition, our minds often leap to thin, scraggly malnourished cats, but actually the commonest form of poor nutrition is a massive over provision of calories, leading to obesity. Obesity is known to actively shorten lifespan and can contribute to many diseases such as diabetes and liver problems. Getting your cat’s weight under control is one of the most beneficial things we can do for their overall health. 

How do I know if my cat is overweight?

There is no one standard perfect weight for a cat, as they all vary in size, breed, age, sex and body shape. The best measure of whether your cat is overweight or not is their body condition score. This measures the body condition and grades it from 1-9, with 1 being very thin to 9 being obese. 

The score is based on markers such as the presence of absence of a noticeable waist, the ease of palpation of prominent bones such as the ribs and spine, and the presence of any fat pads. An obese cat, therefore, is one where the ribs and spine are hard to feel as they are covered in fat, there is no noticeable waist but instead a pendulous tummy area, and where there is noticeable fat deposits in other areas.

Based on the body condition score, an optimum weight can be decided. Cats are classed as ‘overweight’ is they are 10-19% over their ideal weight, and ‘obese’ if they are over 20% heavier. 

Why do cats get fat?

Often there is a simple answer to this question: they are taking in more calories than they are using, known as a ‘positive energy balance’. 

However, there are some known risk factors:

  • Breed – purebred cats are more likely to become overweight
  • Neutering – gain weight easily due to a decreased metabolism
  • Age – overweight cats are more likely in the age range of 2-10 years
  • Certain medications such as corticosteroids
  • Activity level – sedentary, indoor cats burn less calories so are more disposed to be overweight

Does it matter that my cat is a bit chunky?

Yes, it most certainly does! Obesity can have many negative effects on health and is well documented to be associated with a decreased lifespan. 

Being overweight can predispose to certain conditions, or accelerate their progression. These include urinary tract disease, osteoarthritis, diabetes, skin disease and a form of liver disease caused hepatic lipidosis. Obesity can also affect other more general functions, such as negatively decreasing the function of the immune system, increasing complication rates in pregnancy and birth, contributing to breathing problems and increasing anaesthetic risk. 

Managing weight loss

We’ve established that a large proportion of domestic cats are overweight, and we also know that this isn’t a good thing. So, what do we do about it? Anyone who has even tried to lose weight will know that it isn’t an easy task. 

Vetster option 01 (Blog)

Always aim for slow and steady weight loss. Dramatic dieting and weight loss can be very dangerous for cats. It can cause hepatic lipidosis, a serious liver condition caused by a rapid change in metabolism. Seek advice from a veterinary professional about how much weight your cat needs to lose, and some guidance on the period of time to spread the loss over. It can be hard to see the changes day by day in your own pet, so visiting your vet for regular weigh-ins over the course of the process is hugely useful. 

There are a few main areas to focus on.


Cats are carnivores, and their natural diet consists of small, high-protein meals. There are various veterinary weight loss diets for cats, which mostly follow the principle of high levels of good quality protein, but low in carbohydrate and fat. Some also contain high levels of fibre, to help greedy cats feel fuller. Some diets contain specific nutrients to help your cat’s metabolism burn fat faster. Your veterinary surgeon will be able to advise on a suitable diet. Remember to always introduce a new diet slowly, over the course of several weeks.   

Measuring the amount of food given is really important. It is very easy to underestimate how much you are feeding daily if you don’t, or if you ‘top-up’ the bowls throughout the day. Stick to their plan – giving just ‘a little extra’ each day can really derail a diet. Remember that treats can be highly calorific, so cutting these out can be an excellent start to reducing calories – and in some cases, is all that is needed to achieve a better body condition! 

Puzzle feeders

These can be really useful in many ways. Slowing food intake to help satisfaction, encouraging more movement and providing both physical and mental stimulation. There is some excellent information on puzzle feeders here


Calories out are important too! Encouraging movement through play, training to a cat harness or by moving food bowls around, for example, can all help to get those more sedentary dieters moving.

Common barriers to weight loss

Getting your pet to slim down is hard, that’s for certain. There are some common problems that cat owners may face.

  • Cats which pester for food – cats train their owners well! Cats who are always pestering for food may settle better if you split their daily food allowance into multiple small meals, so they feel full more. Also try giving them a fuss or playing with them to redirect their attention from food. 
  • Households with multiple cats – if you have a slim cat alongside your chunkier pet, you may be understandably concerned about food restriction. Try separating your cats to feed them, or feed the slimmer cat somewhere inaccessible to their heavier friend, such as up on a work surface. Microchip cat feeders are available which only dispense the correct amount of food to each cat. 

Maintaining condition

Congratulations, your cat is now at optimal weight and condition! This is excellent, but it is easy for bad habits to creep back in. Continuing to use a lower calorie, or ‘light’ diet, can help keep those cats prone to weight gain slim. Regular weight checks are still needed, as it can be difficult to see those grams sneaking back on. Keeping your cat at their ideal body condition is one of the best things you will ever do for your pet’s health and wellbeing.

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