The new study focused on what’s known as the body roundness index (BRI), a newer assessment of abdominal obesity that looks at waist circumference and height. Body mass index (BMI), an older assessment of obesity, only measures weight in relationship to height, and does not distinguish between lean muscle instead of fat, or account for the distribution of body fat.
“Not all excess body fat poses health risks; in particular, abdominal or (visceral fat) has the greatest health risks, while fat in the thigh area poses the lowest risk,” says Steven B. Heymsfield, MD, a professor at the Pennington Biomedical Research Center at Louisiana State University in Baton Rouge, who wasn’t involved in the new study.
“BRI picks up these shape differences in a single measure better than BMI.”
Even Moderate Levels of Extra Belly Fat Increases Heart Disease Risk
For the study, researchers examined five years of BRI measurements for about 10,000 Chinese adults starting when they were 59 years old on average and had no history of cardiovascular disease events like a heart attack or stroke. Over the last four years of the study period, there were 3,052 cardiovascular disease events and 894 deaths.
Compared with participants who had a consistently low BRI — meaning they carried little if any extra fat around their midsection — people with a high BRI throughout the study were 55 percent more likely to develop heart disease, 46 percent more likely to have a stroke, and 35 percent more likely to have cardiac events like a heart attack, according to study findings published in the Journal of the American Heart Association.
People with a consistently moderate BRI also had a higher cardiovascular risk than participants with a low BRI throughout the study period. Individuals with a moderate BRI were 22 percent more likely to develop heart disease, 29 percent more likely to have a stroke, and 14 percent more likely to have cardiac events like a heart attack.
The new study found BRI associated with cardiovascular risk even after accounting for many factors that can also influence heart health such as age, medical history, medication use, blood pressure, blood sugar levels, and cholesterol levels.
The Study Had Some Limitations
Some limitations of the new study include the relatively brief follow-up period, as well as the possibility that results from Chinese participants might not reflect what would happen for individuals from other racial or ethnic backgrounds.
Even so, the findings suggest that it makes sense to think beyond just BMI when considering the health risks of body fat, Dr. Heymsfield says. That’s because many people with the same BMI can have vastly different fat distribution and muscle mass. This would be true for a bodybuilder and a sedentary non-athlete of the same weight, height, and age, Heymsfield notes.
“The body builder will have less body fat and more body mass in the upper extremities,” Heymsfield says. “That variation in body shape will be captured with BRI, but not BMI.”
That said, BRI shouldn’t be used on its own, either, says Maya Feller, RD, CDN, founder and lead nutritionist at Maya Feller Nutrition in Brooklyn, New York.
“If a person has a high BRI, I recommend not using that as the stand-alone determinant and instead using the data from their most recent physical examination,” says Feller, who wasn’t involved in the new study.
Tests for things like blood pressure, blood sugar, and cholesterol levels can all help give a more complete picture of cardiovascular disease risk than using BRI on its own, Feller says. If you are at high risk, there’s also plenty you can do about it.
“Following a pattern of eating that is abundant in vegetables, fruits, ancient grains, beans, nuts, and seeds — and culturally relevant and accessible — generally reduces chronic disease risk,” Feller says. “Focusing on fiber from grain, beans, nuts, and seeds as, well as a variety of vegetables, can be beneficial and supportive of reducing cardiovascular disease risk.”
