Waist-to-height ratio ‘is better than BMI for predicting health’

Measuring height-to-waist ratio is a ‘much better indicator’ of health than body mass index (BMI), according to research.

Using a tape measure may help pinpoint those who have more fat stored around their vital organs, which can increase the risk of conditions such as heart disease and stroke.

According to experts, if the circumference of the waist is less than half a person’s height, it is ‘a good indicator’ they are at a healthy weight, particularly in older people.

BMI is calculated by dividing a person’s weight in kilograms by the square of their height in metres, while waist-to-height ratio divides waist circumference by height.

But BMI can be a problematic measurement as it does not differentiate between fat weight and muscle weight.

A BMI of more than 30 is classified as obese. In 2023-24, 64.5 per cent of adults in England were estimated to be overweight or obese, with 26.5 per cent classed as living with obesity.

Dr Laura Gray, of the University of Sheffield, said: ‘Quite often we’ll hear that athletes have a BMI over 30 and would be classed as living with obesity, but we know that they’re not. They don’t have excess weight. This study is the other side of that coin.

‘Older people tend to lose muscle when they age, and that means that their body fat percentage is actually higher, but their weight is still dropping, so BMI starts coming down, but actually they’re getting less healthy. Waist-to-height ratio, because it measures round your waist, is giving us a more accurate measurement of visceral fat.’

And visceral fat – which is the fat stored around the vital organs – has ‘more of an effect on how things work within your body’, Dr Gray added.

Backing the height-to-waist measurement, Dr Gray said: ‘A tape measure is actually cheaper than a set of weighing scales. It’s probably easier because it’s just a ratio, rather than squaring something like we do with BMI.’

The study, published in the International Journal of Obesity and led by researchers at the universities of Sheffield and Nottingham, analysed data from the Health Survey for England between 2005 and 2021.

The researchers also found that environment has a ‘significant influence’ on obesity.