5 Reasons Why BMI Is BS

By Danielle Carney, LMHC

We have a lot of unlearning to do as a society to confront weight stigma and fatphobia, and to address the systems that contribute. As a HAES-aligned eating disorder therapist, I believe one of the ways we have to do this is taking a look at how Body Mass Index (BMI) is used in Western Medicine.


We’re all unfortunately very familiar with this scenario: you’re at the doctor’s office, dreading that awful sentence – “I’ll just have you step on the scale.” 


Then, you anxiously await the doctor to come in and review your chart, assess your weight and BMI, and give you feedback about your health accordingly.


Here’s my issue with that:

1. BMI was never meant to be used as a measure of health.

The concept of BMI was developed in 1832 by Belgian statistician Lambert Adolphe Quetelet, who was called on to create a description of the “average man” based on White, European male participants’ heights and weights. He saw this “average” as an ideal for the general population. 


He didn’t create this formula for medical purposes and even spoke out against using it for measuring health. He didn’t know what helped a body to function, or whether a number on a scale had any bearing on lifespan. He didn’t account for muscle, or bodies that weren’t white. He didn’t account for disability or age. Or gender. 


BMI ranges and cutoff points began when life insurance companies attempted to establish a link between weight and someone’s likelihood of dying in the 1940s. They used the BMI formula and several decades of data from mostly White policyholders to create actuarial tables. Physiologist Ancel Keys later coined the term “body mass index” in 1972.


And despite its origins, here we are, 200 years from when the original formula was created – still using an antiquated, inaccurate system as a primary marker in our healthcare.

2. Being in a larger body is not synonymous with being “unhealthy.”

There is so much emphasis on thinness and glamorizing weight loss culturally. Because of this influence, it can be difficult to take a step back from and really look at this deeply ingrained belief and how it affects the way we think as a society.


While higher BMI is correlated with certain conditions on a population level, the first rule of good research (which anyone who’s taken a statistics class knows) is that correlation is NOT equal to causation. You can be healthy in a larger body, just as you can be unhealthy in a thin body.

3. BMI is often considered before assessing eating and exercise behaviors in Western healthcare, contributing to weight stigma and negative provider bias.

Weight loss is often prescribed to patients with a higher BMI due to weight stigma before assessing health behaviors such as eating a balanced, flexible, and varied diet, and practicing regular, healthful movement.


Eating disorders are often overlooked in patients with a higher BMI. Because of this, doctors can cause harm by recommending weight loss to someone already struggling with an unhealthy relationship with food, exercise, and their body. Being an eating disorder therapist, I have heard so many stories about doctors inadvertently perpetuating disordered eating behaviors by recommending diets, increased exercise, and weight loss – ugh! 

4. Race and ethnicity need to be considered.

BMI is a one-size-fits-all approach to health. Humans, however, are all unique with unique racial and ethnic backgrounds, health histories, and genetics.

BMI also perpetuates two things no one likes – racism and sexism. According to Paul Campos, author of The Obesity Myth, ”While Black women have higher BMIs than white women, they also have lower mortality rates at a given BMI.” So, to prescribe the same recommendation for weight across races and ethnicities is not only harmful, but potentially dangerous. It also makes zero sense to base recommendations for Black women, as an example, on a scale developed off the measurements of White, European male participants – come on! We can do better.

5. Body composition is ignored.

BMI does not account for muscle mass, which is just another reason why arbitrary cutoff lines for the sake of “health” is bogus. This can lead to inaccurate treatments and recommendations for people who might already have very healthy lifestyles.   Further, BMI does not consider body composition and weight distribution.

So, what’s the alternative?

Health is not a number on a scale or being within a certain BMI range. I suggest we shift the focus off of numbers and acknowledge maintaining health is an ongoing, multifaceted process, and it needs to be approached as such.


We need to bring the focus to encouraging health-focused behaviors and assessing someone’s relationship with food, exercise, and their bodies. We need to encourage a balanced, satisfying, flexible, and varied approach with food, and we need to shape a similar relationship with movement. 


We need to examine individual differences, genetics, race, gender, and weight histories, and stop with the blanket prescriptions for weight loss to encourage “health.”


We need to get away from using shame as a motivator and focus instead on cultivating joyful, intuitive relationships with the behaviors that make up health.


The best weight is the one where your body feels strong and nourished, and your mood is stable. It’s when you can get restful sleep, and you’re doing the things you love. You can focus and concentrate on what you need to, and your mind is free to think about things other than counting calories and hating your body.


Ultimately, when you’re eating the food you enjoy and that fuels your body effectively, and you’re using exercise as a tool that makes you feel mentally and physically strong and energized, your body will find a weight and shape that is perfect for you. 


As always, a blog post can only begin to cover some of the many nuances of this conversation and the efforts it will take to change. I’d encourage you to do your own research on this topic as well, and check out other HAES resources to supplement the points made here. 



If you’d like to continue the discussion with the support of an eating disorder therapist, you can reach out to me here.

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