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Why is it important?

In the UK, between 40 and 50% of cats are either overweight or obese. It is by far the most common form of malnutrition we see as vets. While we may like to give our pets nice treats and extra meals, we are in fact "killing them with kindness". To understand, and be able to control, our pets' tendency to ballooning waistlines, we need to ask a series of questions:

What is obesity?

An obese cat is one who is more than 20% heavier - due to fat! - than that individual's ideal weight. We call a cat who is 1-19% heavier "overweight".

Why do cats become obese?

Essentially, because we feed them too much. Many cats are by their very nature greedy, and if they ask for more food, all too often we give it too them! Other common problems include us treating them (and feeding them) as kittens even after they've reached their adult size; some people's inability to recognise a cat's healthy weight; increased numbers of neutered cats (who need less calories in their diet than entire cats); and the problem of cats with two or more homes, all of whom feed them.

Why is obesity a Bad Thing?

Obesity is a causative factor in a number of serious diseases, including diabetes, arthritis, cystitis (FLUTD), some skin diseases and liver conditions. In addition, it reduces the effectiveness of their immune system, makes them more likely to suffer problems giving birth, puts increased stress on their heart and lungs, and increases the risk of complications if they ever need surgery.

How do we tell if a cat is overweight?

We use the Body Condition Score system (you can read about it here: This allows us to asses how much fat the cat is carrying around with them, and score them - in this system, 4-5 is the ideal weight, 1 is skeletally thin and emaciated, and 9 is morbidly obese.

What can we do about it?

Essentially, feed less calories and make them do more exercise! Unfortunately, exercise alone doesn't usually resolve the problem, but it does help to increase their muscle tone, heart and lung fitness, and when they've lost the extra weight, they're more likely to keep it off if they are fit.

Surely we can't just stop feeding them?!

Definitely not - suddenly starving a an overweight cat can cause liver failure. The best option is to gradually reduce the amount of food they're getting - we usually look for about 1% of body weight loss per week. Some very hungry (or greedy, or manipulative!) cats won't accept this, so it is often better to change to a weight-loss diet, which is designed to fill them up with a low energy density ration - making them feel full, while providing less calories.

How do I make my cat exercise?

ou could take them for a walk on a lead and harness (and some people do), but expect funny looks! In most cases, encouraging them to play is the better option, usually with chasing or pouncing toys.

In conclusion...

Obesity is a growing problem (pun intended) in the UK's feline population. Fortunately, a number of simple, minor changes in the way we interact with our pets can usually bring it under control. If not, give your vet a call - many practices run regular weight clinics with nurses who will be able to help you!