Why BMI is Outdated & What You Should Know About Body Roundness Index (BRI)

For decades, BMI (Body Mass Index) has been used as the go-to measure for health. But the American Medical Association (AMA) acknowledged in 2023 that BMI is an imperfect tool that doesn’t always accurately measure body fat or reflect a person’s health risks.(1)

So, why do doctors still use it? Habit, convenience, and lack of a better alternative—until now.

Introducing the Body Roundness Index (BRI)

Unlike BMI, which only compares weight to height, BRI factors in waist and hip circumference to assess not just how much fat someone has, but where that fat is stored.

Why does this matter? Because fat stored in the midsection, around your internal organs (visceral fat) is more dangerous than fat stored under the skin (subcutaneous fat). A rounder body shape typically means higher visceral fat, which is linked to serious health risks.

(If you think calculating BMI is complicated, you should see the formula for BRI; unless you’re a math geek, it will make your eyes glaze over. Luckily, it’s easy to find a BRI calculator online, like this one.)

New Research Using BRI

A 2024 study followed 33,000 U.S. adults over nearly 20 years, measuring their BRI and tracking their health outcomes and mortality risk.(2) The results?

1. The roundest people (top 20% for BRI) had a 50% higher risk of death from any cause compared to those in the middle range.

2. Interestingly, the least-round people (lowest 20% for BRI) had a 25% higher risk of death than those in the mid-range. This was the same risk percentage as the second-highest range. (See more on this below.)

3. BRI increased for participants over time – the average person moved from a lower-risk category to a higher-risk one.

Bottom Line

✔ Health is more than just weight. Where fat is stored matters more than just total weight.

✔ Exercise & nutrition help, but genetics play a role. If a person is predisposed to store fat in their midsection, their BRI will be hard to change. Good exercise and nutrition habits will be even more important.

✔ Being thin is not the same as being healthy. As the study showed, even people in the lowest range for BRI had a higher mortality risk, after adjusting for age, income, education and ethnicity. Before these adjustments, participants in this range had a 43% lower risk. Some people are lean due to healthy habits, but others may be thin due to underlying issues like muscle loss, illness, or poor nutrition.

BMI has been the standard for years, but BRI offers a more accurate picture of health. As research continues, we may see a shift in how doctors assess health risks.

References

1. “AMA Adopts New Policy Clarifying Role of BMI as a Measure in Medicine.” n.d. American Medical Association. Accessed October 8, 2024. https://www.ama-assn.org/press-center/press-releases/ama-adopts-new-policy-clarifying-role-bmi-measure-medicine.

2. Zhang, Xiaoqian, Ning Ma, Qiushi Lin, Kening Chen, Fangjieyi Zheng, Jing Wu, Xiaoqun Dong, and Wenquan Niu. 2024. Body Roundness Index and All-Cause Mortality among US Adults. JAMA Network Open 7 (6): e2415051.