Dear Medical Professionals, It’s Time to Throw Out Your BMI Charts
Over the past few months, I’ve had several friends tell me that on their most recent visit to the doctor, they were informed that they were obese. Scientifically, empirically, objectively obese, based on their Body Mass Index (BMI).
When they told me about their experience with their trusted medical practitioners, I had a few reactions:
- Rage — For better or worse, this is frequently my first reaction when something bothers me, but I haven’t yet put my finger on exactly why (shout out to all the Enneagram 1’s).
- Confusion — Wait, are doctors still using that archaic system, after all the progress that’s been made in understanding the human body?
- Sadness — Especially as women, we are constantly told to shrink ourselves (not just physically) and the friends that told me of their doctor-diagnosed obese status ARE NOT OBESE. Not even close. Thankfully, these women are confident, self-realized individuals who aren’t going to let this derail them. But what about the young girls who are still figuring out who they are?
BMI was developed as a way of measuring whether someone has a healthy weight. It’s based on a formula developed in the 1830s (yes, almost 200 years ago) by a Belgian mathematician and statistician, Lambert Adolphe Jacques Quetelet. It factors in weight and height and lands each person along a gradient of underweight, normal weight, overweight, and obese. This was something that was developed before calculators existed. It may have been helpful, however imperfect, for that time, but that definitely doesn’t mean we should still be using it today.
The disturbing simplicity of this tool reinforces an incredibly outdated “one-size-fits-all” perspective of human beings. One of my favorite podcasts, 99% Invisible, has an episode called “On Average” that talks about this issue, although not BMI directly. They show how focusing on designing things for the “average” (whatever that means) person (ahem… usually just men) actually ends up being more inaccurate and unhelpful for everyone. It has taken years to realize that, because every body is so different, we can’t measure things based on the average person.
Here are a few specific things that should disqualify BMI as the medical community’s primary tool for body measurement and health assessment:
- It doesn’t take into account muscle mass, meaning that people like Michael Phelps and Usain Bolt are very close to being considered “overweight” according to their BMI.
- It was designed based on the Caucasian body and most studies of BMI’s efficacy have generally only focused on white people. There are so many problems with this — SO MANY PROBLEMS!
- It assumes that BMI is directly related to health, but in fact, a study published in the International Journal of Obesity showed that nearly 50% of the 40,000 people included in their study that were considered “overweight” were actually healthy in every other way, while 30% of those considered to be in the “normal” weight range were considered unhealthy in other categories. This means that people who are healthy are being told to lose weight unnecessarily, while (possibly even more worrying) people who are unhealthy are told that they don’t need to change anything.
I mean, BMI basically asserts that every 5'9" person (despite muscle mass, body type, ethnicity, bone structure, etc.) should be within the same weight range. That’s just ridiculous. We’ve come a long way in the scientific study of the human body, understanding the complexity and uniqueness of each individual. This oversimplified and outdated system of equating our weight and our health needs to go.
