Comparing a person's waist size to their height is a more effective way of calculating their life expectancy and the methods used currently for working out body mass index (BMI), researchers have said.
BMI is often used to estimate a person's risk of suffering diseases and conditions, but it has long been thought that the system is flawed.
A new study from Oxford Brookes University found that measuring waistlines against height proves more accurate.
According to the research those with a waistline which measures 80 per cent of their height are likely to die 17 years younger than the current national average.
Researchers believes keeping your waist size down to less than half your height can help to lower the risk of developing conditions such as diabetes, heart disease and stroke.
For a man standing 6ft, this means having a waist of less than 36 inches.
Dr Margaret Ashwell, who presented her findings at the European Congress on Obesity in Liverpool earlier this year, said: "If you are measuring waist-to-height ratio you are getting a much earlier prediction that something is going wrong, and then you can do something about it."
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