Abdominal fat significantly increases a person's risk of premature death, even if their overall weight is within normal limits, say researchers.

Researchers examined the association between BMI, waist circumference, and the risk of death using data collected from 359,387 participants enrolled in the European Prospective Investigation into Cancer and Nutrition (EPIC) study.

Results showed that there was a significant association between BMI and risk of death, with higher risks of death observed in the lower and upper BMI categories than in the middle categories – the lowest risk of death was observed in men with a BMI of 25.3 and women with a BMI of 24.3.

The results also showed that waist circumference and waist-to-hip ratio were a “powerful indicator” of risk of death, regardless of BMI. Men with waists exceeding 47″ (119cm) were twice as likely to die early compared with those with waists of less than 31.5″ (80 cm), in women, those with waists over 39″ (99 cm) had double the risk of premature death compared to those of less than 25.5″ (64.7 cm). For people with the same BMI each extra 2″ (5 cm) raised the risk of early death by 17% for men and 13% for women.

The researchers concluded: “The current results underscore the importance of assessing the distribution of body fat even among persons of normal weight and challenge the use of cutoff points to define abdominal obesity, at least when they are used to predict the risk of death. Our finding of a positive association between waist circumference and the risk of death among participants of normal weight may also explain why studies have been unable to show a linear relationship between BMI and the risk of death across the entire range of BMI values.

Pischon T, Boeing H, Hoffman K, et al. General and Abdominal Adiposity and Risk of Death in Europe. NEJM 2008;359:2105-2120.