Body Roundness Index (BRI): a better marker than BMI?

For years, the Body Mass Index (BMI) has been the standard way to judge whether someone is overweight. But BMI only uses weight and height. It cannot tell muscle from fat, or fat on the hips from fat deep inside the belly. The Body Roundness Index (BRI) was designed to do better by looking at your shape. You can work out your own number with our Body Roundness Index calculator.

What is the Body Roundness Index?

BRI was introduced in 2013 by a team of researchers who imagined the human body as an oval, or ellipse. A tall person with a narrow waist is a long, thin oval. A shorter person with a wide waist is a rounder oval. The rounder the shape, the higher the BRI.

The aim was to estimate two things that matter for health:

• Total body fat percentage.
• Visceral fat, the fat packed around your liver, gut and other organs. This deep belly fat is the most harmful kind. It drives insulin resistance, type 2 diabetes, fatty liver, high triglycerides and heart disease.

How is BRI calculated?

You need only two measurements:

1. Waist circumference, measured midway between the lowest rib and the top of the hip bone, after gently breathing out.
2. Height.

Both must be in the same unit, such as centimetres. The formula is too complex to work out in your head, so a calculator does the maths. Weight is not part of the formula at all, which is one of its strengths. BRI values in adults usually range from about 1 for very lean people to above 10 for people with a very round shape.

What do BRI numbers mean?

The best-known study of BRI and health followed nearly 33,000 American adults for about ten years. It found a U-shaped link between BRI and the risk of dying from any cause:

BRI range	Risk compared with the middle group
Below 3.4	About 25% higher
4.5 to 5.5	Lowest risk (reference group)
6.9 or above	About 49% higher

Two points are worth noticing. First, a high BRI, meaning a round middle, was linked to higher risk. Second, a very low BRI was also linked to higher risk. This is probably because very low values often reflect illness, frailty or poor nutrition, not good health. Lower is not always better.

Remember that these are associations in a population study. A BRI number does not predict what will happen to you as an individual.

Is BRI better than BMI?

BRI has some clear advantages:

• It focuses on belly fat, which is closer to what harms health.
• It is less fooled by muscle. A muscular person can have a high BMI but a normal BRI.
• It needs only a measuring tape, so it is cheap and quick.

But it is not a perfect measure:

• It is relatively new, so there is much less research on it than on BMI.
• It may underestimate fat in some body types.
• It is more sensitive to measuring errors, because a small change in your waist reading changes the result.

Does BRI work for Indians?

This is the honest gap. Most BRI research comes from American, European and Chinese populations. There are no agreed BRI cut-offs for Indians yet.

Indians tend to carry more fat around the middle and inside the liver at a lower body weight than Western populations. This is why Indian doctors use lower BMI cut-offs. Read about BMI cut-offs for Indians. In theory, a shape-based measure like BRI should suit us well.

A 2026 study using national health survey data from India looked at how well different body measures picked up diabetes. BRI did about as well as BMI and waist-to-height ratio, but it was no better than the simpler waist-to-height ratio. Waist size itself did slightly better than all of them. So for Indians, simple waist measures remain very useful. Try the waist-to-height ratio calculator: a ratio below 0.5, meaning your waist is less than half your height, is a good general target.

How should you use your BRI?

Think of BRI as one tool among several, not a pass or fail grade:

• Track your own trend. Measure your waist the same way every few months. A falling BRI is a good sign that belly fat is going down, even if the scale has not moved much.
• Use it alongside other numbers, such as your BMI, waist size, blood pressure, fasting sugar, HbA1c and lipid profile.
• Do not panic about a single reading. One measurement can be off by a centimetre or two.

If your BRI is high, it is a good reason to have your sugar, blood pressure, cholesterol and liver checked. Reducing belly fat improves all of these, and in people with type 2 diabetes it can even lead to remission. Read whether diabetes can be reversed.

What should you ask your doctor?

• Is my waist size putting me at risk, even if my weight seems fine?
• Should I be tested for diabetes, fatty liver or high cholesterol?
• What is a realistic waist or weight goal for me?
• Would I benefit from a structured weight-management programme or medicine?

The link between waist size and disease is explained further in waist size and health risk. If you would like a full assessment, you can book a consultation.