Adam’s Journal
Not long ago, I read an article suggesting that physicians were moving away from the body mass index as a medical screening tool. But when I went for a physical last month, my BMI was printed right at the top of the summary I received at the end of my visit. Is my doctor behind the curve?
Dr. Scofield Prescribes
Well, if your physician is out of step, then so am I. Because I still use BMI as one of many ways to measure my patients’ health.
A quick refresher: BMI is a ratio that is used to assess body composition. Technically, it is a person’s weight in kilograms divided by their height squared in meters. That calculation yields a two-digit number, which is often used as a shorthand for whether a person is at a healthy weight, overweight or obese.
BMI has been around for nearly two centuries. Since then, we’ve devised many other means of assessing metabolic and cardiovascular health, including blood pressure, cholesterol, blood sugar and waist circumference.
No single measurement can tell us everything we need to know. So, we rely on all of these metrics – and quite a few others – to gain a full picture of our patients’ health. And BMI remains among those many other factors.
For the majority of the population, BMI can offer a reasonably accurate shorthand for whether a person is at a healthy weight. However, notably, it falls short when people are tall or heavily muscled. For both of these groups, BMI skews high, suggesting that a person may be overweight or obese when, in fact, they are not.
Still, physicians do not look at BMI in isolation: I doubt that doctors assigned any significance to BMI readings that would have labeled as obese Shaquille O’Neal at the height of his NBA stardom or Arnold Schwarzenegger in his Mr. Universe days.
As a measurement, BMI is far from perfect. Physicians and researchers occasionally suggest replacements, and one is measuring the thickness of a person’s triceps skinfold. Like BMI, this approach is simple and free, and it serves as a pretty good proxy for body-fat percentage.
Recently, some have also championed a formula called body roundness index, which seeks to gauge abdominal fat and mid-body obesity.
These are intriguing approaches, and time will tell if they will yield a more accurate picture of metabolic and cardiovascular health. But in the meantime, BMI can still play a role in capturing a snapshot.
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Adam Cohen is OMRF’s senior vice president and general counsel. Dr. Hal Scofield is a physician-scientist at OMRF, and he also serves as Associate Chief of Staff for Research at the Oklahoma City VA Medical Center. Send your health questions to contact@omrf.org.
