Weight loss in cats

black cat on white background


Weight loss in cats is often a sign of a problem. However, it can be hard to spot – especially if your cat is losing weight slowly or if they have a very fluffy coat.

There are many different reasons for a cat to lose weight ranging from minor to serious.

Book an appointment with your vet if you think your cat is losing weight, no matter whether it’s happened suddenly or over time.

Is my cat a normal weight?

Use our handy ‘body condition score’ chart to help you decide if your cat is a healthy weight.

Weight loss and other signs

Quick weight loss is easy to spot but slow weight loss is a more difficult. Other symptoms to look out for include:

When to contact your vet

If you think that your cat is losing weight, then you should take them to your vet for a full check-up.

Make sure your cat is weighed regularly – this will be done every year by your vet as part of their health check and vaccine booster but you can also weigh your cat at home. Watch our video on how to weight your cat at home and learn how to monitor your cat’s body condition score. Both weight and body condition score will help you to notice any subtle changes in your cat’s weight.

Feed your cat a good quality, food appropriate for their age to ensure they are getting all the nutrients they need to live a happy, healthy life.

You know your cat best. If they don’t have the symptoms listed above but you are still concerned it’s always best to contact your vet.

Why is my cat losing weight?


If your cat has worms they may start to lose weight and develop an increased appetite as well as other symptoms such as over-grooming and scooting their bottom along the floor.


Is your cat getting enough food? Could another pet be taking more than their fair share? Make sure your cat is getting enough food and that they have the opportunity to eat it all. Monitor your cat’s weight at home and book an appointment with your vet if they are losing weight or seem unwell in them self. Check out our guide to keeping your cat a healthy weight.

Kidney disease

Kidney disease causes gradual weight loss as well as many other symptoms including increased thirst, a decreased appetite and vomiting.

Dental disease

Cats suffering with tooth and gum disease often appear hungry but are picky with their food. They may initially show interest in food but then hiss or run away from it once they have attempted to eat (due to pain). Cats with dental disease often lose weight gradually.


Hyperthyroidism is an overactive thyroid gland. The thyroid gland controls metabolism so if it’s higher than usual it causes weight loss and increased hunger. Cats with hyperthyroidism tend to lose weight very quickly, constantly demand food and become very vocal or anxious.


Diabetes in cats can cause very rapid weight loss. Other symptoms include extreme hunger and thirst. Diabetes is much more common in cats that have been overweight at some point in their life.


Stress can cause a cat to lose weight. Events such as moving home, a change in routine, being bullied by another cat, another pet joining the household, not enough food bowls, or litter trays in the home can all contribute to stress.

Having kittens

If your cat doesn’t receive enough food in the initial stages of pregnancy or when they are feeding their babies they may lose weight. This is because they are using more energy than they are taking in. Neutering is the best way to avoid unwanted pregnancies.

Other illness

There are multiple conditions that can cause weight loss in cats. Most will cause other symptoms as well. Liver disease, pancreatitis, cancer, inflammatory bowel disease, viral infections such as Feline Immunodeficiency Virus (FIV) and Feline Leukaemia Virus (FeLV) all cause weight loss.

Published: October 2018

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Written by vets and vet nurses. This advice is for UK pets only.

Illustrations by Samantha Elmhurst