The measurement of body fat around the waist is a more accurate indication of risk than body mass index, researchers say.

Beer bellies may double the risk of dying prematurely even among people who aren't traditionally considered overweight, a study of more than 350,000 Europeans suggests.

In Thursday's online issue of the New England Journal of Medicine, researchers confirmed that waist-to-hip ratio measurements are a better way of predicting obesity-related deaths than the standard body mass index or BMI.

Each five centimetre increase in waist circumference increased the annual mortality risk by 17 per cent in men and 13 per cent in women, Dr. Tobias Pischon of the German Institute of Human Nutrition Potsdam-Rehbruecke in Nuthetal, Germany, and his colleagues said.

"The most important result of our study is the finding that not just being overweight, but also the distribution of body fat, affects the risk of premature death of each individual," Pischon said.

"Abdominal fat is not only a mere energy depot, but it also releases messenger substances that can contribute to the development of chronic diseases. This may be the reason for the link."

The relative risk of death among men in the top fifth of waist circumference was 2.05 times greater than those in the lowest fifth, while for men with the highest waist-to-hip ratio, the risk was 1.68 times greater than those in the lowest fifth.

For women, the corresponding figures were 1.78 times greater for waist circumference and 1.51 times greater for waist-to-hip ratio.

Both general fat and abdominal fat were associated with the risk of death, the researchers noted in concluding that waist circumference or waist-to-hip ratio should be added to BMI in assessing the risk of death, even among people of normal weight.

The study's authors adjusted for educational level, smoking status, alcohol consumption, physical activity and height. People with a history of cancer, heart disease or stroke were excluded from the study, which followed participants for an average of nearly 10 years.

BMI is a person's weight in kilograms divided by the square of the height in metres. It is not used for growing children, and may overestimate results for muscular adults such as body builders.

Under Canadian guidelines released in 2007, a waistline of more than 94 centimetres (37 inches) for a man and 80 centimetres (32 inches) for a woman should be considered a risk factor for cardiovascular disease and Type 2 diabetes.