[beingfit]

> But those who were least round were also at elevated risk of death: People with B.R.I. scores under 3.41 also faced a mortality risk that was 25 percent higher than those in the midrange, the study found.

> The paper’s authors suggested the lower scores, seen mostly in those 65 and older, might have reflected malnutrition, muscle atrophy or inactivity.

> “B.M.I. cannot distinguish body fat from muscle mass,” Wenquan Niu, who works at the Center for Evidence-Based Medicine at the Capital Institute of Pediatrics in Beijing and was a senior author of the paper, wrote in an email. “For any given B.M.I., fat distribution and body composition can vary dramatically.”

So, if I understand it right, BMI cannot distinguish body fat from muscle mass and BRI can’t distinguish malnutrition or inactivity. This would mean that whichever metric you choose, you should look at it as well as beyond it.

On the same topic, the formula for BMI is a simple one (weight in kilograms divided by height in meters squared) that you could calculate it on a simple calculator.

The formula for BRI is more complex: [1]

> BRI was calculated as 364.2 − 365.5 × √(1 − [waist circumference in centimeters / 2π]² / [0.5 × height in centimeters]²), according to the formula developed by Thomas et al.

[1]: https://jamanetwork.com/journals/jamanetworkopen/fullarticle...