Why I Hate the BMI

Back in 2018 I found a new PCP and scheduled an appointment for an annual physical. I didn't have a great experience.

In addition to my new doctor being over 30 minutes late and not acknowledging it, she came into the room, didn't look at me, went straight to the laptop on the counter, and told me that I was overweight. For transparency, I was 5'3", 150 lbs, and worked out 4-5 days a week.

I was shocked by her poor bedside manner, the fact that she didn't even look at me, and the fact that she didn't ask me any questions about my lifestyle before concluding that I was overweight.

I immediately decided that that was my first and last visit with her.

This doctor was basing this "overweight" diagnosis on the BMI - body mass index. Body mass index is the measure of body fatness, calculated by dividing body weight (in kilograms) by the square of height (in meters). According to this measure, good health is associated with a BMI of between 19 and 25 while 25.5 to 29 is considered overweight and 30+ is considered obese.

One of the issues with this measure is that does not take into account muscle mass, bone density, or age. This means that it can be inaccurate for some people, such as athletes and older adults.

This measure was formulated in the early 1800s by a Belgian mathematician named Adolphe Quetelet. Quetelet was interested in developing a way to measure the average person, and he believed that BMI could be used to do this. The factors that he used to come up with this measure are discriminatory. For example, his study only included European white men. What about the rest of the population? And by the time we get to the 1900s, health insurance companies built on this measure and they determined what a "normal" weight was - white, average build, and able bodied.

There are so many things wrong with the BMI and I encourage you to dig a bit deeper into its history to learn more about why it is problematic.

While medical professionals use this as a measure of health, I encourage you not to allow it to be the end all be all. There are other ways to determine your state of health - like a blood test.

So push back when you need to and ask for blood tests and provide an accounting of your lifestyle. Also, don't be afraid to fire your doctor.