Dead Center

BMI Is Dead . . . Long Live BMI

A new study in PLOS ONE looks at five ways to measure body proportions – including BMI – and proclaims a winner. It’s not BMI. The winner is waist to height ratio. WHtR beats BMI and other measures in this study because it’s a better stand-in for actually measuring excess visceral fat. Unleash the headlines. BMI is dead.

Not So Fast

We’ve heard this before. BMI is that yardstick that everyone loves to hate – and with good reason. It’s widely misinterpreted as the definition of obesity. That’s wrong. BMI is a signal for obesity, not the definition. It’s a signal for taking a closer look.

Diana Thomas is Professor of Mathematics at the United State Military Academy at West Point. As someone who has made a career of quantitatively studying obesity, she explains:

This is an interesting study, no doubt. But waist to height ratio doesn’t resolve the limitations of BMI. It’s still not a real measure of adiposity. And it adds another problem. Waist circumference is not easy to measure reliably. Error rates can be 20%.

Measuring a person’s waist might seem simple on the surface. But in practice, it’s not. Different people measure it in different ways. It takes training and practice to get consistent measurements. And even then, error rates can be a problem.

Expecting Too Much from BMI

By comparison, measuring height and weight is pretty simple. Calculating BMI is not hard, either. Maybe the only problem with BMI is that we’re expecting too much. BMI doesn’t diagnose obesity. It just calls for a closer look.

So if someone tells you BMI is dead, ask for the obit.

Click here for the study and here for more from Leeds Beckett University. For more on measuring waist circumference, click here. And finally, for more from Thomas on alternatives to BMI, click here.

Dead Center, photograph © Several Seconds / flickr

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June 9, 2017

6 Responses to “BMI Is Dead . . . Long Live BMI”

  1. June 09, 2017 at 7:21 am, Al Lewis said:

    One thing missing from all these measures is: you need a willing subject, someone who genuinely wants to learn the answer. Otherwise these measures are easily gamed — as in corporate weight loss contests. Just suck your waist in a bit before the measurement. Slouch before the first weigh-in and stand very tall before the second. That will change your height.

    The right clothing and water retention will also change your weight. Here are all the ways people cheat — many are bad for one’s health.

    • June 09, 2017 at 7:45 am, Ted said:

      Exactly right, Al, which is the core problem with all the energy that people put into the obesity of other people. Health is a personal issue. Employers don’t need to make people wanna be healthy. They just need to make it easier to be. Beating people up about their health or weight, telling them how to live, imposing penalties…none of that helps. An opportunity to do meaningful work in a humane workplace helps. Respect helps.

  2. June 09, 2017 at 9:25 am, Mary-Jo said:

    If more people who struggle with obesity felt that they would be treated with understanding, respect, dignity, and correct, fair assessment, they would be more willing to seek out and learn answers and to work/comply better on treatments for their disease.

    • June 09, 2017 at 12:50 pm, Ted said:


  3. June 10, 2017 at 8:21 am, Dr. Jon Robison said:

    Given that the treatments for this so-called disease are most likely to fail and very likely to end up with people’s weight increasing that is highly unlikely to happen! The sooner we realize the reality of this clearly supported by more than 30 years of consistent research the sooner we will actually be able to be helpful to people who are struggling with weight related concerns whatever they may be. Dr. Jon

    • June 10, 2017 at 9:53 am, Ted said:

      Thanks for sharing your views, Jon.