The key to a long life is having a waist no bigger than half your height, a new study has claimed.
Researchers said the rule applied regardless of a person's age, ethnicity or gender.
Dr Margaret Ashwell, co-author of the study, said that the evidence was so strong that it should provide the basis for a simple global health check, which anybody could perform with a piece of string if they did not have a tape measure: "Keep your waist circumference to less than half your height."
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The study by Ashwell and researchers from City University London's Cass Business School analysed 20 years of British medical records and measured the impact on life expectancy of obesity, as measured by the ratio between your waist and height, 'The Sunday Times' reported.
Researchers found that a 30-year-old man who is 5ft 10in tall, should have a waist of no more than 35in - but if that expands to 42in, or 60 % of his height, he will lose 1.7 years. His female counterpart, who is 5ft 4in tall, will die 1.4 years prematurely if she lets her waist expand from half her height, 32in, to 60 % of her height, 38.4in.
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A man aged 30, of average height and a 56in waist, can expect to lose 20.2 years, while an obese woman of 30 with a waist of 51in will die 10.6 years early.
However, only 0.2 % to 0.3 % of that age group are so excessively overweight, researchers said.
The study demonstrated that Body mass index (BMI) is particularly poor at predicting early death from obesity for women, while waist to height provides accurate estimates for both sexes.