• Stephanie Dorfman, MS, RD

Why BMI is Not an Indicator of Health

Updated: Mar 31

Visits to the doctor can be stressful and anxiety producing for several reasons. I would say, the main reason is the fatphobia and weight stigma that is significantly present in these offices. Whether it’s requesting patients to be weighed or discussing how their Body Mass Index (BMI) impacts their health - I think it’s necessary to know where these “health indicators” came from. Today - we’re focusing on BMI - let’s dive in.

What is BMI?

The BMI scale measures our weight in relation to our height Just to make things extra clear - BMI ONLY accounts for weight and height - and NO OTHER (legitimate) indicators of health. BMI does not consider MANY important aspects of our health like: lab values, activity levels, blood pressure, and mental health - which may actually help their patients achieve their vision of health.


So, how did BMI become such a prevalent indicator of health?

What are some of the myths surrounding BMI?

How can we further educate ourselves and learn ways to improve our health according to our own definition of health?

Let’s debunk these myths!


Myth #1: BMI was created by medical professionals.

The BMI scale wasn’t actually created by a doctor. It was developed by an academic who studied astronomy, mathematics, statistics , and sociology.


A math equation should not and cannot represent our health - health is much more complicated than that. I have to say, it is a bit silly that we take the answer to a math equation so personally considering it was developed by people who have expertise in non-health professions! Would you go to a doctor to get your car fixed? Definitely not! Same logic goes for going to a math expert for health advice.


Myth #2: Weight is the only indicator of health

Say it with me: WEIGHT IS NOT AN INDICATOR OF HEALTH. Weight and BMI are also not vital signs. We should strive to incorporate joyful movement, self care, self love, and foods that make us feel good, into our lives. These are behaviors we can actually control and choose for ourselves. Similar to how we cannot change our shoe size, height, eye color, etc - weight is not something that we can control.


The BMI scale neglects our mental health, and it can cause lots of anxiety, lower body positivity and self love, and possibly eating disorders/disordered eating from pressure to lose weight! Mental health is a critical piece of our health puzzle that we MUST take care of.


Size and weight are NOT a representation of our health. According to research, “overweight” individuals who work out have decreased risk for all-cause mortality compared to normal weight individuals who are unfit. We must separate weight and health because they are not necessarily correlated.


Check out this awesome blog post by Jill Clodfelter-Mason, RDN, CD, discussing 5 health promoting behaviors that have NOTHING to do with weight.


Myth #3: Your weight must be at a low range

BMI doesn’t take into account our muscle mass. Fun fact; muscle weighs more than fat. BMI cannot tell you the percentage of your body that is muscle mass, fat mass, water, other bodily fluids, so it mistakenly classifies people into BMI categories and changes their perception of their health according to a random number! If we strength train (while participating in joyful movement...principle #9) and try to build muscle, our BMI may increase and that is perfectly NORMAL - because muscle weighs more than fat! Just another reason why BMI and weight are not indicators of health. We may be healthier at a higher weight/BMI than we were at a lower weight/BMI - something to consider. Being smaller or a lower weight does not indicate anything related to our health and fitness levels.


Myth #4: BMI takes effort for doctors to determine

Very wrong! From Rachel Hartley's blog post about The Many Problems with BMI (love how she refers to BMI as the Bulls*** Measuring Index), she describes a doctor's use of the BMI as lazy medicine. It takes about 10 seconds for a doctor to calculate and tell you your BMI. It takes much much longer for a medical professional to have a patient centered conversation of ways to specifically benefit you and your vision of health.


I talk to my clients about this all the time - it is important for us to find a doctor who doesn’t only focus on the numbers on the scale (you are actually not required to be weighed at the doctor and can refuse) but rather on the many other aspects of health.


To Wrap Things Up...

Let’s take a step away from the BMI scale and focus on allllllll of the other health indicators and behaviors that have nothing to do with weight. Next time you’re worried about your BMI, turn away from that thought and remember that there is so much more to you than a math formula.


Looking for someone to chat with about health? Hi there! I am here to listen and provide a safe and supportive space for discussion. Feel free to schedule a free discovery call to learn how we can work together.