Should we ditch BMI and use the ‘body roundness index’ instead? Premium

Learn about the limitations of BMI and the potential benefits of using the Body Roundness Index for health assessments.

Body mass index (better known as BMI) has long been used to get a quick and easy snapshot of a person’s body fat levels. To calculate someone’s BMI, you divide their weight in kilograms by their height in metres times itself. The resulting number is used to determine a person’s health risk.

Although there are far better ways of getting an accurate measure of a person’s body fat levels – such as using dual-energy x-ray absorptiometry (Dexa) or magnetic resonance imaging (MRI) – these are very resource-intensive. This may explain why BMI has remained the go-to method for measuring health since it first started being used in the latter part of the 20th century.

But many health experts believe BMI has significant limitations, particularly for children and young people (whose body fat levels change as they grow), athletic people (who have high levels of muscle mass) and people from ethnic minority groups (who may develop health problems at lower body fat levels).

BMI was never created for use in health and was developed using data from European people in the 19th century. Although child and ethnicity‐specific adjusted BMI and alternative height and weight ratios have been suggested, none have made sufficient headway to improve BMI’s reputation.

Several alternatives to BMI have also been suggested – such as using waist-to-hip ratio (waist circumference divided by hip circumference) or body volume index (which uses 3D body scanners to estimate total body fat distribution).

But a recent study suggests that instead of BMI, we should be using something called body roundness index (BRI) to get a more accurate picture of a person’s body fat levels and predict health risk.

BRI was developed by U.S. researchers in 2013 in response to criticisms of BMI. Instead of looking at height and weight, BRI mathematically quantifies body fat levels by looking at height and waist circumference instead. This provides a value typically ranging from one to 20. It is the lowest and highest values that suggest the highest health risk.