MILLIONS of middle-aged people have been mistakenly led to think they are not obese, a study has revealed.
Italian scientists have found scaling back the body mass index (BMI) threshold for obesity to 27 could give a more accurate picture of who is affected.
As people get older, muscle declines and more fat builds up around organs and the stomach, often leading to no measurable difference in weight.
Having excess belly fat can be especially dangerous and puts people at greater risk for developing several kinds of health problems – including heart disease and diabetes.
While BMI calculates someone’s overall weight, it doesn’t consider where fat is stored.
It comes up with a number, usually between 14 and 42, by dividing an adult’s weight in kilograms by the square of their height in metres.
According to the age-old method – still hailed by the World Health Organisation (WHO) and NHS doctors alike – people with a BMI of 30 or more are obese.
The new study, presented at the European Congress on Obesity, looked at body fat instead of weight related to height.
They compared the BMI scores and body fat percentage results of 4,800 Italian adults aged 40 to 80.
Just 38 per cent of the men and 41 per cent of the women had a BMI above 30 – but when their body fat percentage was calculated using scans, 71 per cent and 64 per cent were found to be obese.
Professor Marwan El Ghoch of the University of Modena and Reggio Emilia said: “This new BMI cut-off recognises the physiological differences between middle-aged and older adults and younger populations.
“It’s likely that the changes in body composition across the lifespan, which seem to occur without a meaningful change in body weight, lead to higher adiposity at a lower BMI.”
The analysis suggested that 27 is the ideal BMI cut-off point for obesity in older adults, with an accuracy rate of 90 per cent.
However, researchers stressed the limitations of the study, which was carried out in just one area of Italy.
The body mass index is a formula used to decipher whether patients are of a healthy weight.
Measurements may also reveal that you are clinically classed as underweight, overweight or obese.
How do I calculate it?
If you’re good with numbers then you can divide how heavy you are by your height in metres squared.
But who wants to do that when the NHS has created a handy tool for you to use.
The tool evaluates your age, gender, height and weight, before estimating your BMI.
When do I need to worry?
After you have calculated your BMI you will be given a number, usually between 18.5 and 30.
Those who have a BMI of 18.5-25 are considered to be a healthy weight.
If your number is between 25 and 30 you are considered overweight and if it goes above 30 you’re considered obese.
The NHS recommends people stay within the healthy weight for their age and height.
If you are not within a healthy weight range, you are at a much greater risk of obesity-related illnesses like heart disease, stroke and diabetes.
But on the other end of the scale, you can also be underweight.
Anyone with a BMI under 18.5 is considered underweight and is more at risk of immune system problems, fragile bones and infertility
Other important factors, such as eating habits, exercise, and sleep patterns, were not considered.
Professor Antonino De Lorenzo of the University of Rome Tor Vergata added: “If we continue to use the WHO standard for obesity screening, we will miss many middle-aged and older adults who are at risk for obesity-related diseases including type 2 diabetes, heart disease, and some cancers.
“Establishing this new BMI cut-off point in clinical settings and obesity guidelines will be beneficial to the potential health of millions of older adults.”
Losing weight should be a long-term commitment to healthier living, rather than any drastic measures.
The NHS tips – which can be adopted slowly – include:
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