Body mass index was first developed in 1832 and has been the standard way to estimate a person’s body fat since the 1980s. The calculation, however, has come under increasing scrutiny in recent years.

One major critique of BMI is that it doesn’t look at how much of a person’s weight is fat, and where fat is distributed around the body. It also doesn’t take into account the other elements that make up a person’s body composition beyond fat, including muscle, bone, water and organs.

“Fat distribution and body composition can vary dramatically among different people with the same BMI,” Wenquan Niu, a professor at the Capital Institute of Pediatrics in Beijing, wrote in an email.

Because muscle is much denser than fat, BMI skews higher in people who are very muscular but have less body fat, like athletes https://www.nbcnews.com/health/health-news/bmi-flaws-body-roundness-index-better-rcna155898