The Pervasive Force of Weight Bias, Part 1 – The BMI

The BMI has come to be the defining force when it comes to “healthy weight” in our society, but what do we actually know about the BMI as a measure of health? As a physician, a personal trainer, and most importantly a woman who strives to lead a healthy life, I’ve had countless interactions with the BMI but somehow never really questioned the validity of it - what it is actually measuring? - until the past few months. Maybe it was my listening to the Maintenance Phase podcast, or maybe it was the recent American Academy of Pediatrics guidelines updating their recommendations on childhood obesity, or maybe it was the recent influx of people in my world searching for a “quick fix” weight loss plan. Whatever it was that pushed me to ask, “why do we put so much weight on weight?”, I’m grateful.

The BMI was invented in the 1830s by Lambert Adolphe Jacques Quetelet, a Belgian statistician, sociologist, astronomer, and mathematician, not a physician, who sought to analyze a population at-large (and a homogenous white European population to boot) and did not intend to use BMI as a measure of individual body fat, build, or health. Fast forward to the 1970s when Ancel Keys and his colleagues published a study suggesting that the BMI “proves to be at least as good as” any other existing index to measure body fat, propelling the BMI to become a first-line assessment of health. An index that at its inception had no intention of analyzing people on the individual level is now at the forefront of individual health care.

With all its faults, these days the BMI is still used endlessly as a quick assessment tool by medical professionals as it helps busy physicians focus on higher risk populations since an obese BMI is associated with a significant increase in morbidity (including diabetes mellitus, hypertension, dyslipidemia, heart disease, stroke, sleep apnea, and cancer) and mortality. The BMI, though, is also used unfortunately, on a very regular basis for people to judge others’ weight, and subsequent health, without knowing anything about the person – their medical problems (or lack thereof), medications, dietary habits, exercise routine, etc – except what they look like on the outside.

I don’t have a solution on how to change the ubiquitous societal problem of anti-fatness, although I really wish I did. But what I can do, especially in my role as a primary care doctor, is stop the perpetuation of the idea that weight defines health. Sure, when generalized, people labeled as obese by BMI have a higher risk of hypertension and diabetes, but on an individual level, weight is certainly not the sole determinate of what causes these and other illness. “Normal weight” individuals can have heart disease too.

So again, what can I do? I can focus on the individual and not the BMI. I can give you the time to listen and give you individualized guidance and support. Practicing at CLIMB Health & Wellness rather than an enterprise-associated, insurance-dictated, traditional medical practice that relies on the BMI to shortcut visits, affords me the grace to do this and see people as people. I can understand and discuss the nuances of health, talk about eating habits and exercise habits and sleep habits and ask about how mental health plays into it all. I can display, teach, and encourage healthy lifestyle habits in a non-shameful way. I can help people listen to their minds and bodies and understand that the number on the scale does not define them or their health. It’s complex because people are complex. And I’m determined to be here for that.