Q. Body mass index (BMI, mg/kg2) is the best known and most common way to measure body fat and obesity. However, we’ve also heard about the body roundness index. What is this, and how is it used? (N.L., Reno, NV).
A. The Body Roundness Index, or BRI, first described in 2013 (Obesity. Silver Spring. 2013; 21:2264), may be another helpful tool for clinicians. The BRI calculates body fat using height, weight, waist circumference, and sometimes hip circumference as well, to assess all-cause mortality. Obesity, especially visceral obesity, is a well-known risk factor associated with cardiovascular events and all-cause mortality.
A recent article by Xiaoqian Zang, MD from Brown University and his colleagues reports that US adults with lower-than-normal and higher-than normal BRI scores were at greater risk of death from all causes. Because BRI takes into consideration waist circumference, it can more accurately reflect visceral fat distribution, say the authors. They used data from 32,995 US adults from the National Health and Nutrition Examination Survey (NHANES) from 1999 to 2018 and the NHANES Linked Mortality File to study mortality through December 31, 2019 (JAMA Netw Open. 2024. 7:e2415051). Since 1999, the NHANES has been conducted every 2 years, using in-home interviews and study visits at mobile examinations centers.
Nonpregnant adults 20 years old or older were included in the authors’ study. The average age was 47 years, and slightly more than half were women. The sample included 2779 non-Hispanic Whites, 1113 non-Hispanic Blacks, 1471 Mexican Americans, and a group of 469 individuals classified as “Other.”
The national cohort study also showed an increasing trend in BRI over a nearly 20-year period among US adults, and a U-shaped association between BRI and deaths from all causes. The BRI increased steadily over the 20-year period, from 4.8 to 5.62. The risk increased by 25% among those with BRIs less than 3.4 and by 49% among those with BRIs of 6.9 or greater. The trend was more obvious within certain groups, including women, the elderly, and those who identified as Mexican American. The authors noted that very low BRI was associated with a significantly increased risk of all-cause mortality, especially in those 65 years of age or older.
BRI scores range from 1 to 20 (1 = narrow body, 20 = more round) and represent a graph of body shape with reference to a healthy zone. It is not superior to BMI, waist circumference, or waist-to-height ratio but has been helpful and was better than the BMI for assessing male and female patients for diabetes and cardiac risk in Northeast China (JAMA Netw Open. 2023. 6:e2334836).
Janice Goldschmidt
Has worked with individuals with IDD for the last decade, and written and presented her work in a range of professional formats. She received her Master’s degree in Nutrition from the University of Maryland-College Park, where she initially developed her program for development of food preparation skills, Active Engagement. As Director of Nutrition Services at Community Support Services, Inc. (Gaithersburg, MD), she has continued to build on Active Engagement, which now includes many differing contexts for guiding individuals with IDD and autism to independent cooking skills. She has also worked on the identification, classification, and treatment of eating disorders for this population.