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For years, body mass index (BMI) has been the go-to measure for assessing body fat and associated health risks. This simple calculation, based on height and weight, has long been used to categorize individuals as underweight, normal weight, overweight, or obese. However, critics argue that BMI is an imperfect tool, failing to account for variations in body composition and fat distribution. Enter the Body Roundness Index (BRI)—a novel metric that could offer a more nuanced approach to evaluating obesity and health risks.
What Is the Body Roundness Index?
The Body Roundness Index, or BRI, is designed to measure a person’s “roundness” and is calculated using height, waist, and hip measurements, but not weight. Developed by Diana Thomas, PhD, a professor of mathematics at West Point, and introduced in a 2013 study published in Obesity, BRI aims to better capture body fat distribution, particularly abdominal fat, which is closely linked to health issues such as cardiovascular disease and diabetes.
Dr. Ali Rezaie, a gastroenterologist and associate clinical professor at the University of California, Los Angeles, explains, “Abdominal fat is a strong predictor of cardiac disease, diabetes, and even risk of death.” The BRI scale ranges from one to sixteen, with higher scores indicating a rounder body shape. This scale is intended to provide a more detailed picture of body fat distribution than BMI.
Why Consider BRI Over BMI?
BMI has faced criticism for its one-size-fits-all approach, failing to account for factors such as sex, race, age, and ethnicity. It also doesn’t differentiate between fat and muscle, potentially misclassifying muscular individuals as overweight while missing those with normal weight but high abdominal fat.
Dr. Luke Twelves, a general practitioner and vice president of medical at Lindus Health, highlights the limitations of BMI: “BMI can misclassify people, labeling muscular individuals as overweight or obese, while failing to identify individuals with normal weight but high abdominal fat as being at risk.”
In contrast, BRI offers a more comprehensive evaluation by incorporating waist and hip measurements, potentially providing a more accurate reflection of body fat distribution. Recent studies have shown that BRI correlates strongly with health risks, including mortality. A study published this June found that higher BRI scores were associated with an increased risk of death from any cause. Conversely, lower BRI scores, particularly in older adults, may indicate malnutrition or reduced activity tolerance, which are also associated with poor health outcomes.
Scientific Support for BRI
Research supports BRI as a potentially superior alternative to BMI. For instance, Diana Thomas’s 2013 study demonstrated that BRI predicts abdominal fat better than BMI. A meta-analysis in 2020 further confirmed that BRI outperforms BMI in estimating risks for conditions like metabolic syndrome and colorectal cancer. Additionally, a 2021 study found a strong correlation between BRI and insulin resistance, a precursor to diabetes and cardiovascular disease.
Challenges and Considerations
Despite its promise, BRI is not without its challenges. Dr. Areces points out that more research is needed to validate BRI across different populations. Variability in waist measurement techniques can impact accuracy, as noted by Dr. Naomi Parrella. Additionally, interpreting BRI values can be more complex compared to the straightforward BMI cut-offs.
Dr. Rezaie acknowledges that while BRI offers a potentially better measure, it is still relatively new and has not been as extensively studied as BMI. Furthermore, Dr. Britta Reierson expresses concern about the term “round” in BRI, which could be perceived as stigmatizing.
The Future of Body Measurement
As the medical community continues to evaluate BRI, it’s clear that BMI alone may not provide a complete picture of health. The Body Roundness Index represents a step towards more nuanced and individualized assessments of body fat and related health risks. As research progresses, BRI could become a valuable tool in the quest for more accurate and equitable health measurements.
