Does Your Body Shape Determine How Long You’ll Live? According to New Science, Maybe
The Body Roundness Index may be a better indicator of longevity than old-school metrics.

The Body Roundness Index may be a better indicator of longevity than old-school metrics.
A new medical measurement called the body roundness index (BRI) might predict longevity more accurately than long-held measures like BMI. Unlike BMI, which only measures weight relative to height, BRI focuses on body shape (waist circumference and fat distribution), which researchers suggest could be a key to understanding overall health and mortality risks. Meaning, BRI could be a better predictor of longevity than BMI, which has been in use for more than 50 years (1).
About the Experts
Michael Thelwell, Ph.D., is a research fellow in advanced human body measurement techniques within the School of Sport & Physical Activity at Sheffield Hallam University, Sheffield
Aaron Riviere, R.D., is a registered dietitian and lecturer at Texas A&M University in College Station, Texas.
Dr. Peter Brukner is a medical doctor, dietitian, and chairperson at Defeat Diabetes.
The BRI is aptly named: It’s designed to capture a person’s “roundness.” A person’s BRI represents their height, waist circumference, and hip circumference.
The BRI scale ranges from 1 to 16, with higher scores indicating a rounder body shape. A rounder body indicates more visceral fat, the type of fat found in the midsection that surrounds vital organs and is linked to higher risks of chronic diseases, including metabolic syndrome, diabetes, and heart disease.
First proposed in 2013 by Diana M. Thomas et al., BRI is a novel measurement that could “quantify the individual body shape in a height-independent manner”—AKA figure out someone’s body type without height skewing the results. According to that initial research, the new index slightly improved predictions of body fat percentage and visceral fat percentage compared to BMI, waist circumference, and hip circumference (2).
Since then, research has shown that BRI is a better predictor of metabolic syndrome, while others suggest it is an equal predictor of cardiovascular health, hypertension, insulin resistance, and diabetes compared to the aforementioned established measurements (3, 4, 5, 6, 7).
While BMI only considers weight and height, BRI accounts for fat distribution, especially abdominal fat, which is closely linked to higher mortality risk (1).
“BRI has the potential to be a more accurate and equitable measure across different populations because fat distribution varies by ethnicity, gender, and age,” Riviere says. “BMI can be the same for individuals with very different fat distribution patterns, potentially overlooking important differences in health risk.”
BRI’s core advantage is its ability to assess visceral fat, which has a more direct relationship with chronic diseases than general body fat. BRI accounts for this, making it a potentially more reliable tool for estimating long-term health risks.
Interestingly, BRI follows a U-shaped curve when predicting mortality risk, unlike BMI’s J-curve. Very low and very high BRI scores are associated with increased mortality, reflecting the dangers of both undernutrition and obesity (8).
“Individuals with the lowest risk of all-cause mortality fall in the middle range of the BRI scale,” says Riviere. “Those at both the lower and higher ends of the spectrum experience a greater risk of mortality. When plotted on a graph, this relationship forms a U-shaped curve, with the lowest point in the middle (indicating the healthiest range) and increased risk at both extremes.”
In contrast, BMI follows a J-shaped curve in predicting mortality risk, according to Riviere. “Underweight individuals have a moderately higher risk according to the BMI, but the curve rises more steeply for those in the obese category,” he says. “This creates a J-shape on a graph, with a smaller rise on the left for underweight individuals and a sharper increase on the right for those in the overweight and obese categories.”
Like BMI, BRI has limitations when assessing different populations, from ethnicities to age to athletic groups. However, it may still outperform BMI for certain groups.
Research shows that even when BMI is the same, different populations store fat in different areas, which affects their health risks (9). For example, higher levels of visceral adipose tissue pose a greater risk for chronic disease and may not be accurately reflected by BMI, Riviere says. While BRI is still being investigated in diverse groups, research shows that Chinese men and women have higher visceral adipose tissue levels than European populations when compared with BMI, Riviere points out (10).
“This could put the Chinese population at greater risk for mortality at the same BMI,” he says. “As more populations are studied, it is likely that other groups will also benefit from a more nuanced understanding of body composition and fat distribution, making BRI a potentially more effective tool than BMI for assessing health risks.”
Brukner offers another example: “After menopause, women often notice more fat around their belly area,” Brukner says. “This can indicate bigger health risks. BMI might miss these risks, but BRI may not.”
While it’s not yet as widely adopted as BMI, BRI is gaining traction in academic settings. However, it still has limitations.
While BRI is promising, experts caution against relying too heavily on any one metric to determine health risks. Health is multifactorial, and no one-size-fits-all solution exists when predicting longevity.
Thelwell warns that any new metric showing improvement over existing measures could be misused or relied upon too greatly.
“So long as people are made aware of the potential inaccuracies in a new measure, like BRI, as well as any assumptions or limitations that it may include, then we can avoid any overreliance upon it as has been the case with BMI,” Thelwell explains.
Body composition varies along several axes, including the ratios of fat to lean tissue and organs to muscle tissue, as well as the distribution of fat between central and peripheral (e.g., arms and legs), adds Thelwell.
However—and this is crucial—Thelwell says, “Though these traits manifest themselves outwardly as variations in body build and shape, we will only ever be able to estimate what is actually happening inside the body [with measurements like BMI and BRI].”
Riviere says that though BRI fixes some concerns with BMI, “it still reduces individuals to a single number, which may lead to categorical labeling” and ignores other factors like muscle mass, lifestyle, and metabolic health.
“A more comprehensive assessment would include biomarkers like HbA1c, lipid levels, physical activity, and diet alongside anthropometric data,” he adds.
Experts are optimistic about BRI’s potential to become a standard in clinical practice, though its implementation is still in the early stages. Brukner notes that while BRI could replace BMI, the transition will neither be simple nor quick, as health professionals have been using BMI for decades, and change takes time.
BMI has been the go-to health metric for decades, but its limitations may outweigh its benefits. BRI, which focuses on body shape and fat distribution, offers a promising alternative. Can it determine how long you live? Not quite, but there’s promise. Just don’t expect BRI to fully replace BMI any time soon.