The Body Roundness Index (BRI): Could it Replace the BMI?

In the evolving field of medical metrics for evaluating obesity and health risks, the Body Roundness Index (BRI) has emerged as an intriguing alternative to traditional measurements like Body Mass Index (BMI). Introduced in 2013, BRI takes weight out of the equation and is designed to focus on a person's height and waist size to quantify visceral fat. Let’s see how BRI works, its benefits, and current research on its use to determine if it really could replace the BMI.

What Is the BRI?

The BRI is an abdominal obesity-related index that models the human body as an ellipse, or an egg shape, and aims to capture an individual’s body roundness. Unlike BMI, which only uses weight in relationship to height, the BRI calculation incorporates waist circumference, providing insight into a person’s body girth. This approach allows BRI to estimate body fat more accurately, especially visceral fat (the fat surrounding internal organs), which is linked to a higher risk of metabolic and cardiovascular diseases.

To calculate BRI, healthcare providers need only a measuring tape for waist circumference and a person’s height. A formula is then used to arrive at a BRI score, which ranges from 1 to 20 (1 = narrow body, 20 = more round). Most individuals fall between 1 and 10, with higher scores indicating greater midsection roundness. Generally, a BRI score above 6.9 is associated with increased health risks. You can use an online calculator, like this for the calculations.

Advantages of BRI Over BMI

BMI is commonly used to assess obesity due to it’s widespread accessibility and ease of use, but it has limitations. One of the primary issues with BMI is its inability to differentiate between fat mass and lean body mass (such as muscle). For instance, an athletic individual may have a high BMI due to muscle but little body fat, leading to a misleading classification of “overweight” or even “obese.” Because BMI can neither reflect the visceral fat nor distinguish between muscle and adipose tissue, BMI may not be an optimal marker of measuring human adiposity. BRI, by including waist circumference, provides a more direct estimation of fat distribution, potentially yielding a better assessment of body fat and health risks associated with obesity.

What Does the Research Say?

Since its introduction, studies have explored the accuracy of BRI in predicting health risks. Research suggests that BRI is effective for estimating body fat and identifying risk factors for diseases. Key findings include:

• Increased Mortality Risk: Individuals with higher BRI scores (6.9 and above) were found to have a 49% increased risk of all-cause mortality compared to those with moderate BRI scores. This suggests that body shape, as measured by BRI, can be a significant predictor of mortality risk.
• Predicting Metabolic Syndrome and Liver Disease: High BRI has been linked with metabolic syndrome and nonalcoholic fatty liver disease (NAFLD). In studies, BRI and the abdominal volume index (AVI) were most effective for predicting NAFLD risk, as well as for stratifying risk by demographic factors such as age and race.
• Association with Cardiovascular Risk: In comparison to BMI and other indices, BRI has shown promise in predicting risks of cardiovascular diseases and conditions like hypertension, dyslipidemia, and hyperuricemia. Studies in certain populations, such as Chinese women, demonstrated BRI’s effectiveness in identifying individuals at risk for these conditions.

Despite these promising results, it’s worth noting that BRI is a relatively new metric with a smaller research base than BMI or waist-to-height ratio, which limits its clinical application for now. Additionally, factors like ethnicity, lifestyle, and family history—significant determinants of health—are not included in BRI calculations, which may reduce its predictive accuracy in some cases.

Clinical Implications for Medical Professionals

While BRI shows promise, clinicians need to consider it as part of a broader assessment rather than as a standalone indicator. Here are some practical takeaways:

1. Consider BRI for a Fuller Health Picture: BRI may offer valuable insights into a patient’s visceral fat and associated risks, which can complement other measurements like BMI and waist-to-height ratio.
2. Use in Populations with High Muscle Mass: For athletes or individuals with high muscle mass who may be misclassified by BMI, BRI may offer a more accurate health assessment.

Final Thoughts

BRI represents a promising advancement in anthropometric measurements, offering a more detailed look at body composition and health risks than traditional BMI. While further research and validation is needed to establish BRI’s role in routine clinical practice, it is a potentially valuable tool for medical professionals seeking a more nuanced understanding of body shape and associated health risks.

References:

Body Roundness Index and All-Cause Mortality Among US Adults