How do you define cat obesity and human obesity?

The definition for obesity if different for cats and people. Surprisingly for domestic cats ‘obesity’ is defined as ‘greater than 15% above an ideal weight’. Not much above an ideal weight which is why a lot of domestic cats fall into the obese category. Obesity is the ‘most prevalent nutritional problem in pets in Western Europe and the United States and affects between 10 and 20% of pet cats’ (K. Sturgess and K.J. Hurley). The vast majority of cases are caused by overfeeding or overeating. Too many calories going in and no enough calories being burned.

What is the ideal weight!? Well, it’ll vary hugely between gender, breeds and individual cats so all you can do is check visually if your cat looks 15% or more overweight. That sounds very vague but I think it is pretty accurate as almost all cat caregivers understand what a regular domestic cat looks like unless they’ve normalised obesity. What I mean is that sometimes people can lose their bearings on an ideal weight both for themselves and their cat.

Here is a cat with an ideal weight (he is my boy):

Gabs sits on tablecloth because it felt warmer than the cold stone kitchen counter
Gabs sits on tablecloth because it felt warmer than the cold stone kitchen counter. Photo: MikeB
Two useful tags. Click either to see the articles:- Toxic to cats | Dangers to cats

And here is another.

Correct weight cat
Correct weight cat. Photo: Warren Photographic with his permission.

For humans we work out obesity by reference to their BMI – Body Mass Index. I’ll quote the NHS in the UK if I may.

Definition of BMI

“The BMI calculation divides an adult’s weight in kilograms by their height in metres squared. For example, A BMI of 25 means 25kg/m2.

If your BMI is:

  • below 18.5 – you’re in the underweight range
  • between 18.5 and 24.9 – you’re in the healthy weight range
  • between 25 and 29.9 – you’re in the overweight range
  • 30 or over – you’re in the obese range.”

Here is an example calculation once again from the NHS where by the way the NHS will work it out for you using a form.


If you weigh 70kg (around 11 stone) and are 1.73m (around 5 feet 8 inches) tall, you work out your BMI by:

  1. squaring your height: 1.73×1.73 = 2.99
  2. dividing 70 by 2.99 = 23.41

Your result will be displayed to 1 decimal place, for example 23.4.

How bad is the human obesity problem in the US?

The National Institutes of Health (.gov) in the US says this about the human obesity epidemic in America:

Nearly 1 in 3 adults (30.7%) are overweight. More than 1 in 3 men (34.1%) and more than 1 in 4 women (27.5%) are overweight. More than 2 in 5 adults (42.4%) have obesity (including severe obesity). About 1 in 11 adults (9.2%) have severe obesity.


Personally, I don’t really care if people accept being obese except that it makes them unhealthy which clogs up the health service. I am more concerned about our cats and dogs! They are the vulnerable ones; the victims of you like. They are obese because of what their human caregivers do.

Diabetes epidemic too!

There has been a parallel epidemic of type 2 diabetes in domestic cats. We all know that a cat with type 2 diabetes is very likely to suffer from the disease because they are obese. The cure? Lose weight gradually to avoid fatty liver disease. There is a remarkable success rate in curing type 2 diabetes by simply losing weight. Easy with a bit of self-discipline. Much easier than treating a cat suffering from the disease at home.

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