BRI BMI Health: An Alternative to Body Mass Index

He said that one major drawback of BMI is that it does not account for fat distribution. It doesn’t measure abdominal obesity, bone weight, or muscle mass, and it fails to recognise ethnic differences in body composition.

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“As a result, someone can be what’s referred to as “TOFI”—Thin on the Outside, Fat on the Inside. This means a person may have a normal BMI but still be metabolically unhealthy due to fat stored in the wrong areas,” said Dr Jayadevan.

What are these “wrong areas”? It generally refers to abdominal obesity, but this doesn’t just mean fat around the belly button. Abdominal obesity involves visceral fat, or intra-abdominal fat, which accumulates within the abdominal cavity.

This type of fat is considered particularly unhealthy as it is metabolically active and associated with inflammation, metabolic syndrome (including hypertension, diabetes, and dyslipidemia), and cardiovascular diseases such as coronary artery disease and stroke.

“We measure parameters like weight and height to assess an individual’s risk for these health outcomes. However, relying solely on BMI can lead to underestimating or overestimating that risk,” said Dr Jayadevan.

Then what’s the accurate measure?

Enter the Body Roundness Index (BRI), a new measurement that claims to better estimate body fat distribution, especially visceral fat, which is linked to serious health conditions like cardiovascular disease and diabetes.

Chief Interventional Cardiologist at Gleneagles Hospitals in Hyderabad Dr M Sai Sudhakar said that the Body Roundness Index (BRI) is a relatively new metric used to estimate body fat distribution based on height and waist circumference, as opposed to BMI, which only considers height and weight.

“BRI aims to offer a more nuanced understanding of body shape by factoring in the waist’s roundness, which is linked to fat accumulation, particularly around the abdomen. BMI, while easy to calculate, does not differentiate between muscle and fat or where fat is distributed. BRI is designed to provide better insight into the risk associated with fat stored around the organs, known as visceral fat, which BMI does not account for directly,” said Dr Sudhakar to South First.

Dr Jayadevan pointed out that the key now is to focus on abdominal fat. Waist circumference, which is different from hip circumference, has gained prominence as a reliable measure of abdominal obesity.

“Hip circumference is measured at the widest part of the hips, but waist circumference is taken at the narrowest part of the torso, typically midway between the lower end of the rib cage and the top of the hip bone—something most people can feel with their fingers. Waist circumference has become increasingly recognised in recent years as an important indicator of abdominal obesity, which is a critical health parameter,” said Dr Jayadevan.

Dr Sudhakar said that BRI offer a better estimation of body fat distribution, particularly visceral fat. Visceral fat is closely linked to cardiovascular disease and metabolic disorders, and BRI takes waist circumference into account, which is more indicative of this harmful fat.

“BMI, on the other hand, only considers overall body weight and height, without distinguishing between fat distribution or muscle mass. By focusing on body shape and waist size, BRI is more closely tied to abdominal fat, which is a key factor in assessing health risks. Therefore, BRI is considered more effective in predicting diseases associated with central obesity,” said Dr Sudhakar.

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The study

A recent study published in JAMA Network Open revealed that a higher BRI was linked to an increased risk of mortality from any cause in a large retrospective analysis of nearly 33,000 adults in the United States.

This research not only highlights the ongoing obesity crisis in the U.S. but also points to BRI as a promising new tool in the effort to combat obesity. The study’s authors note that while BRI is almost as simple to calculate as BMI, it provides a more accurate reflection of body composition and associated health risks.

“On one end, individuals with a very low BRI might be underweight due to an underlying disease, which could contribute to their frailty. This connection between low body roundness and increased mortality risk is well-established in medical research,” Dr Jayadevan said.

He added on the other end, individuals with a high BRI—indicating extreme obesity, particularly abdominal obesity—also showed a higher risk of all-cause mortality, which refers to deaths from any cause. In both extremes, the health risks and mortality rates rise significantly.

“For South Asians, the recommended waist circumference range is 80-90 centimetres, based on several studies. The Body Roundness Index (BRI) incorporates both waist circumference and height into a specialised equation to assess body fat distribution,” he said.

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How to calculate BRI

Developed by mathematician Diana Thomas in 2013, BRI evaluates body shape by incorporating both height and waist circumference, which offers a clearer picture of body fat distribution, particularly around the abdomen.

Online, a person can calculate their BRI by clicking here.

BRI calculator sample

This formula reflects the geometric shape of the body, treating it as an oval rather than a cylinder, which is the assumption made by BMI.

Limitations of BRI 

While BRI improves upon BMI by focusing on fat distribution, it also has some limitations.

Pointing at limitations, Dr Jayadevan said that BRI can’t be calculated by simple arithmetic; it requires the use of a calculator or an online tool due to its complex formula.

BRI requires more precise measurements, particularly waist circumference, which can vary depending on how it’s measured. Inaccurate waist measurements may lead to incorrect BRI values.

“People might inhale to make their waist appear smaller, or they might measure the widest part of the abdomen, which could lead to overestimating the waist size. Proper measurement typically requires two people—one to hold the tape and the other to ensure proper posture. This can be cumbersome and is another challenge in using BRI,” said Dr Jayadevan.

Dr Sudhakar added that BRI might not be as widely applicable across different populations, as body shapes can vary significantly based on ethnicity, age, and gender. “Another potential drawback is the complexity of BRI compared to BMI, which is simpler to calculate and more widely used in healthcare. These factors could limit the widespread use of BRI in some settings,” said Dr Sudhakar.

He also said that while BRI has potential to be adopted in clinical settings, widespread adoption might be slow due to several challenges. BMI is deeply ingrained in public health and clinical practice because it is simple to calculate and requires only height and weight, whereas BRI requires additional measurements, such as waist circumference, which may not be as readily available or consistently accurate.

“Another barrier is that healthcare providers and the public are familiar with BMI, so transitioning to a new metric would require education and standardisation. Inconsistent measurement techniques and the need for specialised training in BRI use could further complicate this transition,” said Dr Sudhakar.

Also, he added that it is unlikely that BRI will fully replace BMI, but it has great potential to complement it and other health metrics. BMI remains a useful and straightforward tool for assessing general population-level obesity trends.

“BRI, along with other metrics like waist-to-hip ratio and body fat percentage, can provide more specific insights into a patient’s health. In clinical practice, using BRI alongside BMI and other measures could offer a more holistic view of a person’s risk for cardiovascular disease and metabolic disorders,” said Dr Sudhakar.

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(Edited by Ananya Rao)