The body mass index, or BMI, has long been the standard for assessing body composition and potential obesity-related health risks. However, the BMI has its limitations.

Registered dietitian Kimmie Sharp says there are some concerns with BMI because of its inability to differentiate between muscle mass and fat mass.

“When I used to work in primary care, I’d have patients referred to me for obesity who were actually bodybuilders,” Sharp says. “They had very healthy diets and did plenty of activity, but they were incorrectly flagged as being obese because BMI isn’t perfect.”

Enter the body roundness index, or BRI, a relatively new metric aimed at providing a more accurate assessment of body composition. It measures central adiposity, or fat distribution around the midsection. 

“Fat around the midsection has been tied to a variety of different, not-so-great health outcomes,” Sharp says. “So, BRI is primarily intended to measure that.” 

How is BRI calculated?

Calculating BRI is slightly more complex than calculating BMI. While BMI only requires a person's height and weight, BRI involves measuring the waist and, potentially, the hips. 

These measurements are then used to calculate a score that reflects the roundness of one's body. Although this may be less convenient than measuring BMI, it aims to provide a more accurate representation of an individual's body composition.

“Theoretically, BRI would help to account a little bit better for muscle mass,” Sharp says. “However, it still needs to be further researched and fully validated – there have been just a few studies on it so far.”

BRI advantages

There are some potential advantages of BRI over BMI. These include:

1. Better differentiation between muscle and fat: One of the primary advantages of BRI is its potential to better account for muscle mass. BMI often flags individuals with high muscle mass as overweight or obese, which can be misleading. By focusing on central adiposity, BRI aims to provide a more nuanced understanding of body composition.

2. Focus on central adiposity: Central adiposity, or fat around the midsection, is a significant indicator of health risks. BRI targets this specific area, potentially offering a more accurate assessment of related health conditions.

3. Potential for more accurate health assessments: While BRI still needs further validation through more extensive studies, preliminary research suggests that it could provide a more accurate assessment of obesity and related health conditions compared to BMI.

Challenges

There are also potential challenges and limitations to using BRI in clinical settings. These include:

1. Measurement convenience: BMI is easy to measure because only height and weight are needed. BRI, on the other hand, requires waist and possibly hip measurements, making it less convenient for quick assessments.

2. Need for proper training: Accurate BRI calculations depend on precise waist and hip measurement, necessitating proper training for health care professionals. Mismeasurements can lead to inaccurate assessments.

3. Social sensitivity: The concept of "body roundness" might be considered offensive or sensitive by some individuals, potentially leading to resistance to adopting this measure.

Integration into health care

While some researchers are taking a closer look at BRI, for it to be integrated effectively into health care, several factors need to be considered:

• Research and validation: More extensive studies are required to validate BRI and its correlation with health risks.
• Training: Health care professionals need proper training to take accurate measurements.
• Patient education: Patients need to be educated on the limitations of BMI and the advantages of BRI.

“Potentially, it could help give patients a better indication of their health,” Sharp says. “With that being said, as a dietitian, I already do a lot of education with patients about the limitations of BMI and using it as a marker, but not the be-all, end-all.”

Sharp, who works with patients at the Nebraska Medicine Bariatrics Center, says BMI is used to determine whether a patient is a candidate for certain surgeries and medications. It is also used by insurance companies to make decisions about coverage for bariatric surgery.

While BRI could become a valuable tool in assessing body composition and related health risks, for now, it is not being used as a replacement for BMI.

“We’ve had decades upon decades of studies indicating that higher BMI is tied to increased risk of health conditions,” Sharp says. “We'd want more research to that end with BRI. It’s something I will keep my eye on and see what happens in the future.”

If trying to lose weight seems like a never-ending struggle and you could use some help from medical experts, the Nebraska Medicine bariatrics team may be able to help you overcome your weight-loss challenges. Call 402.559.9500 to get started.