Evidence from the US NHANES III (Third National Health and Nutrition Examination Survey) suggests that central obesity, as assessed by a high waist-to-hip ratio (WHR), confers a greater risk of cardiovascular and all-cause mortality than general obesity as assessed by BMI. As such, a person with a normal BMI but with central obesity has a greater risk of dying than a person with an overweight or obese BMI but without central obesity.
The authors evaluated the data of 15 184 adults (52.3% women) aged 18–90 years between 1988 and 1994, with subsequent follow-up until 2006. During this time there were 3222 deaths, 1404 of which were due to cardiovascular disease. People with a normal BMI but central obesity (defined as a WHR of ≥0.90 in men and ≥0.85 in women) had the greatest risk of death. For example, a man with a normal BMI (22 kg/m2) and central obesity had greater all-cause mortality risk than one with similar BMI but no central obesity (hazard ratio [HR], 1.87), and twice the mortality risk of those who were overweight or obese according to BMI only (HR, 2.24 and 2.42, respectively). Similarly, women with normal-weight central obesity had a higher mortality risk than those with similar BMI but no central obesity (HR, 1.48) and those who were obese according to BMI only (HR, 1.32).
These findings add to the evidence that BMI is a poor indicator of individual mortality risk. Clinicians should supplement BMI measurement with measures of central obesity, such as WHR, waist-to-height ratio or waist circumference.
The study can be read in full here.
