STEVE INSKEEP, HOST:
If you would rather not step on a scale to help calculate your BMI, or body mass index, in which your weight is a factor - if you'd rather not do that, we have an excuse to skip it. NPR's Allison Aubrey reports there's a more helpful way to measure your health.
ALLISON AUBREY, BYLINE: The scale has never been Mana Mostatabi's friend, nor has BMI, which is a ratio of weight to height. She's 38 years old, and as far back as high school when she was a competitive athlete, her BMI put her in the overweight category.
MANA MOSTATABI: At my fittest - like, I ran high school track. But it's because I am a muscly person. Like, my dad always joked that I should have been a wrestler.
AUBREY: She was always trying to get the scale to budge. What she realizes now is that BMI tells you very little about your health.
MOSTATABI: And I'm pretty sure it's really intended for, like, white males. So it's never going to take into account how much muscle you have or the fact that you're women, and, you know, women have breasts and hips. That's just sort of part of what we are.
AUBREY: So Mostatabi now has a new way to track with a body composition test done at her workout studio, part of a national chain called Orangetheory Fitness. She steps onto a device called an InBody, which looks like a metal scale with two arms. It measures her body fat and her muscle mass, two key metrics important for health.
MOSTATABI: So you get on the scale. You're supposed to wipe your hands and feet with these special cloths that, like, allow for better electrical currents.
AUBREY: The machine uses what's known as bioelectrical impedance, sending safe electrical currents through your body, explains Scott Brown, vice president of fitness at Orangetheory.
SCOTT BROWN: And how fast that current is returning to the different electrodes is going to give a measurement of how much fat or muscle you have because the current travels through those body tissues at different speeds or different rates.
AUBREY: Mana Mostatabi's first InBody analysis was back in January. She says her fitness had fallen off during the pandemic, and she was aiming for a fresh start. So all winter long, she did five to six classes a week, a combination of resistance training, weightlifting, cardio on a treadmill and rowing.
MOSTATABI: At the end of the transformation challenge, I had lost 10 pounds of body fat and also gained four pounds of muscle. And it was just so affirming.
AUBREY: Instead of focusing on what she weighed, she was now focused on metrics that matter more to her health.
MOSTATABI: And the InBody scan is actually the first tool I've ever used that showed gains. And to see that I could grow so much muscle as a woman just is incredibly empowering.
AUBREY: Dr. Richard Joseph is a physician focused on metabolic health. He's also a former fitness trainer. He agrees that measuring changes in muscle mass and body fat can be more helpful than just weight and the flawed BMI.
RICHARD JOSEPH: I think it's a really important question around whether or not it's important to get body composition analysis done, and I would say affirmatively, yes, to that.
AUBREY: There are lots of types of body composition tests. Dr. Joseph refers some of his patients for DEXA scans, and MRIs are considered the gold standard. But they're both more expensive and less accessible. The bioelectrical impedance tests, like the one Mana Mostatabi had, are increasingly offered at gyms and fitness centers as part of a membership.
MOSTATABI: Having a machine that can really, like, break it down for me and show me where I'm at and what my progress is -it's just - it's a totally different mindset.
AUBREY: Much more useful than a standard scale - Allison Aubrey, NPR News.
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