BMI is Bullshit

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Last updated on March 6th, 2023 at 10:34 pm

Our current hallmark of health, the BMI chart, Is racist by nature and scientifically lacking, As we examine the pitfalls of this problematic wellness measurement tool, it’s easy to see that BMI is bullshit. 

BMI (or body mass index) is problematic for many reasons including: 

  • It’s racist
  • It’s sexist
  • It can’t distinguish between lean body mass and body fat 
  • BMI doesn’t reflect health status 
  • It can’t accurately predict future health outcomes
  • It doesn’t reflect gender differences in body composition 

Despite its shortcomings, BMI is often used as the primary tool for determining a person’s health status. 

Let’s dig into why BMI is a load of crap, some of the reasons why it is still used, and what we can use to measure health instead. 

History of BMI

BMI has originally coined the “quetelet formula” and was developed by Adolphe Quetelet.  The original intention of the BMI calculation was not to predict health, but rather to determine the average man. 

Quetelets education was as a mathemetician and astronomer, not a healthcare provider or researcher. 

BMI as a tool to measure health was problematic from the start as it was designed to: 

  • Measure populations, not individuals
  • Search out the mean body size of populations, not measure health
  • Determine premiums for life insurance in the early 20th century

BMI measures the weight divided by the height squared of a person.

Contrary to popular belief, the BMI scale was not used as an indicator of health until several decades after its creation when it was used for determining life insurance policies. 

BMI scales only became popular with life insurance companies only as a result of a lack of other ways to predict health status.  

After life insurance companies began to adopt the BMI scale as a measurement of health, physicians began to follow this practice. 

Why BMI is Inaccurate and Misleading 

BMI is bullshit because it is inherently racist and sexist, and can’t measure anything about the human experience aside from a weight-to-height ratio.

Some of the ways BMI is inaccurate and misleading include:  

  • BMI was invented in the 1830’s and hasn’t changed since then
  • It’s based on statistics from the 1830’s when people had less access to proper nutrition 
  • BMI is based on the body types of  women who were shorter with lower lean body mass (due to the culture and expectations in 1830) than women today
  • Women in general are underrepresented in statistics used to create the BMI scale
  • It’s designed to measure social averages not individual people 
  • Most of the statistics used to create the BMI chart come from white males in the 1800s
  • BMI is a poor indicator of current or future health status

Does BMI Measure Health 

BMI is a poor predictor of health.  At its best, BMI can predict correlational relationships between body weight and health risks. 

A correlational relationship does not mean that one event causes another, even though two events may occur together sometimes.

BMI is a poor indicator of health because: 

  • Correlation does not equal causation (high body weights cannot be determined to cause poor health outcomes)
  • BMI can’t measure the bone mineral density
  • BMI doesn’t account for differences in bone size 
  • The best health outcomes are seen in those in the “overweight” category 
  • We only see an increased rate of disease at the highest and lowest ends of the BMI spectrum
  • The increased rates of disease at the highest and lowest ends of the spectrum are only slightly higher than others on the scale
  • BMI does not account for age (which is a greater indicator of health complications)

Is There Anything BMI Is Good For

There is one way in which BMI is helpful. BMI is a tool that can track trends in growth. This is key in determining how a person is growing on their own curve and can be used to prevent or treat malnutrition.

Assessing BMI growth curves can be helpful for conditions like:

Infographic of problems with BMI

Why Do We Still Use BMI

Despite the fact that many healthcare providers will agree that BMI is outdated and flawed, we still use it.  

Some of the reasons BMI is widely used in healthcare include: 

  • We haven’t agreed on a better measuring tool to replace it
  • BMI is often required for insurance coverage
  • Sometimes BMI is right about poor health outcomes and a higher BMI
  • It’s convenient which makes it attractive to providers
  • Other screening tools for health cost more money

BMI is a great way to justify fatphobia and keep diet culture alive.  BMI is perfectly suited to justify the oppression of fat bodies in healthcare by allowing providers to prescribe weight loss for people outside of normal BMI ranges in place of other medical interventions.  

Despite the fact that most healthcare providers recognize the extreme limitation of the BMI scale and that it is an outdated tool for measuring health it is the go-to tool for clinical assessment.

How BMI Harms In Healthcare

BMI is harmful when used in healthcare because: 

  • It can lead to problems being missed by dismissing them as weight-related
  • Weight stigma can lead to poor health outcomes
  • Thin privilege allows thin-bodied people to receive evidence-based healthcare while overweight or obese people are simply told to lose weight 
  • Being told to lose weight constantly can lead to depression and anxiety 
  • It can lead to a fear of gaining weight for people in all body sizes
  • BMI as a marker of health can lead to eating disorders
  • Overweight/Obese does not mean someone is unhealthy

Weight bias may also cause people to feel afraid to tell their providers if they have an eating disorder. 

Patients may also be instructed to cut out foods or restrict in the name of health which could potentially lead to conditions like orthorexia. 

BMI serves as the perfect tool for providers to attempt to eradicate health problems that do not even exist on the basis of “it might happen someday.” 

Infographic describing why BMI is bullshit

How To Measure Health Besides BMI

There are many variables that measure health better than BMI.  To get an accurate measurement of health, we have to consider the whole experience of the person. Thus multiple variables must be considered. 

Instead of BMI try assessing: 

BMI is outdated, does not represent real populations, and does not predict health outcomes.  For all reasons outside of assessing a persons personal growth trends, BMI should be eliminated as a tool in healthcare.

Shena Jaramillo. Registered Dietitian
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