The secret to a long life is having a waistline no larger than half your height, scientists claim.
A study by Cass Business School at City University in London, based on two decades of medical research, said a waist to height ratio of 80 per cent or more could reduce life expectancy by up to 20 years.
Dr Margaret Ashwell, who co-authored the study, said: “Keep your waist circumference to less than half your height.
“People are living in false hope if they rely on their BMI figure. We have got to measure the right thing.”
Unlike waist to height measurement, BMI does not distinguish between fat and muscle.
Dr Ashwell said the average 30-year-old, 5ft 10in tall man should have a waist of no more than 35in. This would put him in the healthy category.
If his waist expanded to 42in or 60 per cent of his height, he risked losing 1.7 years of life and if it increased to 56in he could die 20.2 years earlier.
An average 30-year-old, 5ft 4in tall woman risked dying 1.4 years earlier if she let her waist swell from half her height, 32in, to 60 per cent of her height, 38.4in.
If her waist increased to 51in, she could die 10.6 years earlier.
Children should be measured from the age of five to eliminate them from being at risk of obesity and associated health problems as adults, the study suggested.
Les Mayhew, a professor of statistics at Cass Business School, said: “There is now overwhelming evidence that government policy should place greater emphasis on waist to height ratio as a screening tool.”
Dr Ashwell, who popularised the discovery that apple-shaped obesity is more dangerous than pear-shaped, said BMI was particularly poor at measuring early death due to obesity in women.
The waist measurement method provided more accurate readings for both sexes.