Based on the principle of body eccentricity, it provides a rapid visual and anthropometric tool for health evaluation.

Instead, BRI quantifies body girth as well as height, potentially providing more accurate estimates of fat mass.

[2][3] In a 2020 review, high BRI was associated with increased risk of metabolic syndrome and several other diseases.

[1][3] As a relatively newer predictive metric, BRI has a smaller research record compared to long-established indices like the BMI and waist-to-hip ratio, so its accuracy and applications remain to be as fully established.

Conversely, the simple waist-to-height ratio (which uses the same measurements and is simpler to calculate) has a better research base, leading to its adoption as the preferred guideline in some countries.

[1][2] Thomas visualized the human body shape as an egg or ellipse rather than as the cylinder model that is envisioned in the concept of the BMI.

[1][2] The degree of circularity of an ellipse is quantified by eccentricity, with values between 0 to 1, where 0 is a perfect circle (waist circumference same as height) and 1 is a vertical line.

[1] As the conventional index associated with obesity research, the BMI has numerous drawbacks, as it is unable to distinguish between muscle and fat, is inaccurate in predicting body fat percentage, and has poor ability to predict the risk of heart attack, stroke or death.

[9] BRI was also a better indicator than the BMI and body shape index for predicting the risk of hypertension, dyslipidemia, and hyperuricemia in Chinese women.