Researchers have found that belly fat, which has earlier been linked to increasing the risk of diabetes and heart disease, also increases the risk of early death. In the study, one of the largest, longest health studies in the world researchers found waist size to be a "powerful indicator" of risk.

The study found that people with the most belly fat had double the risk of dying prematurely as compared to people with less belly fat. This risk held even if the overall body weight was normal.

Lead author Tobias Pischon, MD, MPH said, "Our study shows that accumulating excess fat around your middle can put your health at risk even if your weight is normal. There aren't many simple individual characteristics that can increase a person's risk of premature death to this extent, independent of smoking and drinking."

The researchers, who included some from Imperial College London, studied 359,387 volunteers from the ongoing European Prospective Investigation into Cancer and Nutrition (EPIC) health study, over the next 10 years. The subjects were an average of 51 years old at the start of the study, during which time 14,723 of them died.

They studied two measures of abdominal obesity, waist circumference and waist-to-hip ratio. The 'hip/waist ratio' is a number produced by dividing the waist size by the hip measurement. They found that some people had normal body mass index (BMI) scores, but had a larger than average waist size, were at a significantly higher risk of early death.

The researchers specifically found that men who had waist sizes larger than 40 inches and women of 35 inches had double the risk of dying prematurely as compared to men with waist sizes less than 34 inches and women of less than 28 inches. Every two inch increase in the waist circumference was associated with a mortality increase of 17 % in men and 13 % in women. The waist/hip ratio also was a strong predictor of mortality.

Pischon 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."

Professor Elio Riboli, from Imperial College London, said, "The good news is that you don't need to take an expensive test and wait ages for the result to assess this aspect of your health - it costs virtually nothing to measure your hip and waist size."

A British Heart Foundation spokesman said, "If you tend to gather weight around your middle, increasing the amount of activity you do and watching what you eat will help to reduce your risk of heart disease and of dying early."

The study was published in The New England Journal of Medicine.