BMI is WRONGLY branding millions of people unhealthy

The use of Body Mass Index to assess a person's health has led to millions of people incorrectly being labelled overweight or obese, researchers claim.

The measurement has been used by doctors for more than 150 years, but has come under increasing criticism for being a flawed marker of health.

BMI is worked out by dividing weight in kilograms by height in metres, and dividing the answer by height again.

Typically, a BMI below 18.5 is regarded as underweight, 25 or over is 'overweight' and 30 or more is categorised as 'obese'.

A BMI between 18.5 and 24.9 is considered normal. 

The measurement is entrenched in healthcare, used for diagnosing conditions such as anorexia - and to calculate life assurance premiums.

It is also key to official guidelines for treatment - for example, who qualifies for gastric surgery on the NHS.  

Now, however, Californian researchers claim their research will be will be 'the final nail in the coffin for BMI'.

The study, published in the International Journal of Obesity, analysed the link between BMI and several health markers, including blood pressure, glucose and cholesterol levels.

This revealed almost half of Americans who are labelled 'overweight' by virtue of their BMIs (47.4 per cent, or 34.4 million people) are healthy, as are 19.8 million who are considered 'obese.'

However the analysis also found more than 30 per cent of those with BMIs in the 'normal' range, - about 20.7 million people - are actually unhealthy based on their other health data.

And more than two million people who are considered 'very obese' by virtue of having a BMI of 35 or above are actually healthy.

Psychologist Professor Janet Tomiyama, of the University of California, Los Angeles, said: 'Many people see obesity as a death sentence.

'But the data show there are tens of millions of people who are overweight and obese and are perfectly healthy.'

She said that the findings incorrectly label more than 54million Americans as unhealthy. 

In the US, the study also raises questions about the issue of health care costs and raising insurance premiums for those who have piled on the pounds.

Yet many companies are using their employees' BMIs as a factor in determining workers' health care costs. 

And people with higher BMIs could soon have to pay higher health insurance premiums in the US, if a rule proposed in April by the Equal Employment Opportunity Commission is adopted. 

Professor Tomiyama said given their health readings other than BMI, the people in both of those groups would be unlikely to incur higher medical expenses, and it would be unfair to charge them more for health care premiums.

In previous research, she found there was no clear link between weight loss and health improvements related to high blood pressure, diabetes and cholesterol and blood glucose levels.

But she admitted even she was surprised at the magnitude of the numbers in her latest study.

She said: 'There are healthy people who could be penalised based on a faulty health measure, while the unhealthy people of normal weight will fly under the radar and will not get charged more for their health insurance. 

'Employers, policy makers and insurance companies should focus on actual health markers.'

Study co-author Jeffrey Hunger, a doctoral candidate at the University of California, Santa Barbara, added the research showed BMI is a deeply flawed measure of health.

He added: 'This should be the final nail in the coffin for BMI.'

Instead, he recommends people focus on eating a healthy diet and exercising regularly, rather than obsessing about their weight, and strongly opposes stigmatizing people who are overweight.

The proposed EEOC rule would allow employers to charge higher insurance rates to people whose BMI is 25 or higher.

Many people, doctors included, focus on weight as an indicator of health. However, weight obviously varies with height. 

Therefore, we often use a measure called Body Mass Index or BMI, which takes into account your height by providing a ratio of weight to height. 

To work out your BMI you need to divide your weight in kg by your height in metres.

Then divide the answer by your height in metres again.

So, for example, a 100kg woman with a height of 1.6m will have a BMI of 100 /1.6/1.6 = 39kg/m2.

Depending on your BMI, you will then fit into one of the following categories, which reflect the potential health risk. 

Any BMI over 35 is a serious risk to health, so much so that people may be eligible for surgery to reduce that risk.

However, before you get hung up on the BMI scale – it has its limitations. 

It is not as useful for children for instance, nor for athletes who may have a high BMI but very little fat… all their weight is muscle!

So, a lot more focus is now placed on waist measurement as an accurate measure that correlates better with health risk.

The study I mentioned earlier assessed data from over 650,000 people and found that the risk of disease increased consistently with every 5cm increase in waist measurement.

This was to the point where they predicted that those people with the largest waist measurement would die three to five years earlier than those with the lowest.

It was worrying to see from this and another review, that even people with normal BMI but increased waist measurement had a 20 per cent increased risk of dying early than people with normal BMI and normal waist circumference. 

So it seems our waist measurement really is the one to keep an eye on. 

Being a ‘healthy weight’ is not enough anymore.

The waist-to-hip ratio is an even more useful indicator that someone has an 'apple' shape. 

If your hip measurement is a lot smaller than your waist measurement, you are in trouble.

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