Why BMI is bullshit

BMI, or body mass index, is a “tool” that's talked about frequently in our medical system, in health classes, and in news articles that measures weight in relation to height. I put tool in quotations because typically a tool is something useful that helps carry out a certain task/project, and BMI literally doesn’t measure anything of significance.

BMI uses height and weight to classify people into the categories “underweight”, “healthy”, “overweight”, “obese”, “morbidly obese”- all of which have a line that’s arbitrarily drawn to separate the categories without any other factors taken into consideration. The terms  “overweight” “obese” and “morbidly obese” are especially problematic because they are stigmatizing and create shame-you will not hear them used in my practice. Also, over *what* weight?? BMI is not reliable. I’m not going to link to anything that talks about how to calculate BMI or what your *score* is because it doesn’t matter and it’s not helpful-I’m here to debunk it and to empower you to throw out BMI.

The BMI was invented over 200 years ago by a Belgian MATHEMATICIAN-that's right, knew nothing about the human body, was not a DOCTOR or health professional- named Lambert Adolphe Jacques Quetelet. He came up with BMI to help the government allocate resources to the population, and had nothing to do with how “healthy” someone was. Quetelet even requested that the formula was not to be used to measure fatness, or someone’s health status.

I’m angrily typing up this post because I truly thought BMI had been debunked by now. However TOO MANY of my my clients, friends, family, colleagues, and instagram followers have told me horror stories about things they were told about their BMI, how they were classified and put into a box with no other information besides their height and weight, how they were shamed, and how they were denied adequate medical care and life saving procedures.

“If you can just get into the ‘normal’ category, you will be SO much healthier” is said to many people in larger bodies who have phenomenal labs, exercise regularly and engage in healthful eating behaviors-aka true measures of health. People in larger bodies are often not even asked ANY questions about their lifestyle, what behaviors and habits they engage in, or how they feel. Assumptions and judgements are made because of their size.
“You need to drop your BMI by X amount of points to decrease your risk of disease” to people who have been struggling with yo-yo dieting, gaining and losing the same weight over and over again trying to decrease their BMI, putting them at higher risk for things like metabolic syndrome and insulin resistance due to yo-yo dieting.

“You moved into the obese category-you should really start watching what you eat and exercising” was said to my client who gained weight in her recovery from anorexia, who used to excessive exercise and run herself into the ground.

“Your 4 year old daughter is going to end up with diabetes if you don’t get her BMI down”

“You will move up on the list of priority to get a new kidney if you could just get your BMI under X”

“If you want to get bottom surgery sooner, you need to decrease your BMI” -said by a doctor someone who is transgender and has an eating disorder.

These are just a FEW examples of really harmful things that have been said to real life humans-my clients, things I’ve heard doctors say to patients, things that I’ve heard people say about strangers bodies. Maybe these are even thoughts you’ve had people.

Not only are people being dismissed due to their size, they are also being told to do something impossible AND shamed when they don’t conform. People are being denied LIFE SAVING SURGERIES due to their BMI.

Some may argue, better surgical outcomes have come from surgeries done on people with lower BMIs. But, if more surgeries are being done on people with lower BMIs and not even attempted on people in higher BMI categories, that would make sense that more positive outcomes and data are available just due to sample size. And riddle me this: how will there be better surgical outcomes when someone is intentionally undernourishing themselves to get into a lower BMI category to get a surgery? Research actually shows that malnutrition that affects surgical healing happens most often in those with lower BMIs.

What has been your experience with BMI? Have you been to a clinic to get treatment for the flu just to be told you are “overweight” ,“obese” or “morbidly obese”? You likely left feeling SO much shame and guilt, and that you should do something about your body. Likely, you’ve always tried to do something about your body. I’m sure you’ve been on SO many diets to try and *fix* your BMI. I’m sure you’ve tried “eating less and moving more” per common advice, and time after time the weight you lost that moved you into “lower’ BMI category was regained until your resilient body said “no more” and can no longer lose the weight. Maybe you even struggle with disordered eating or an eating disorder, and being categorized by your BMI fueled destructive thoughts and behaviors. Your body is not broken or wrong- BMI is.

Using BMI to determine someone's health is quite possibly the most unhelpful, harmful AND not to mention inaccurate tool-so why is it so prevalent in medicine, research, and insurance coverage? I wish I had an answer. But shaming someone for falling into a certain BMI category  never improved anyone’s health. BMI is absolute bullshit and can’t measure your health or worth.