Please note: At Change Creates Change, we do not use language such as ‘overweight,’ ‘underweight,’ ‘healthy,’ or ‘unhealthy.’ However, we will refer to these words for the purpose of this blog post.
What is BMI?
Body Mass Index, or BMI, is often used to measure an individual’s weight compared to their height.1 BMI is calculated by dividing an adult’s weight in kilograms by their height in meters squared, then the resulting value is categorized into labelled cut-off points.1
BMI functions as both the measurement of a bodily attribute (weight related to height) and also the definition of a condition (obesity or overweight).2 The issue with this method of measurement is that it’s often inaccurate and a poor marker of health.1
History of BMI
Adolphe Quetelet, a Belgian statistician, developed the formula for BMI in the early 19th century.1 However, Quetelet’s goal was not to measure average weight at an individual level or determine an individual’s health status, rather it was to be used at population level.1 The cut-off points that we know today were decided by the National Institute of Health.1
These cut-off points were later changed and, overnight, millions of Americans in the “healthy” category were now classified as “overweight”.1 This illustrates that these categories are arbitrary labels chosen to dictate what is considered an acceptable body weight, and not an accurate indicator of individual health. Despite the issues surrounding the use of BMI, it continues to be used by healthcare professionals.
Problems With BMI
One of the most glaring issues with using BMI as a measurement of health is that the calculation does not differentiate between the weight of muscle and fat.1 This means that athletes with substantial muscle mass may be considered “overweight” according to BMI categories even though they are at peak athletic health1. In addition, BMI does not scale very well, meaning a tall individual with the same body composition as a shorter individual will have a higher BMI.1
Is BMI Accurate?
Since BMI was never intended to be used on an individual level, it is not an accurate indicator of health. Still, health professionals are trained to check and use BMI. Often, they may not have a choice, especially in public settings, where there tends to be policies and standard procedures that include checking weight and BMI.1 Unfortunately weight stigma is still a big problem in the healthcare system and those with higher BMIs find themselves the recipient of increased negative stereotyping and their medical complaints can be mistaken for weight-related problems.3
Effects of Weight Labels
A study by Essayli et al. in 2017 aimed to explore the psychological impact weight labels may have on individuals. This study randomly informed participants that they were of “normal weight” or “overweight”.4 This study found that a label of ‘‘overweight’’ may have negative effects on women’s body image, internalized weight bias, and perceived health.4 Participants that were assigned a label of ‘‘overweight’’ reported greater negative emotions than those assigned a label of ‘‘normal weight”. Similarly, “normal weight” participants that were told they were ‘‘overweight’’ reported greater body dissatisfaction.
This illustrates how stigmatizing these labels can be and that the language used to describe body weight can be damaging to an individual’s mental health. With all of the flaws associated with BMI, why is so much value placed on arbitrarily chosen categories? An individual’s body weight or BMI alone are not accurate indicators of health and there are many other factors that dictate an individual’s wellbeing.
Are You Interested in Learning More?
At Change Creates Change Eating Disorder Care, we strive to educate other healthcare professionals about eating disorders. If you are interested in learning more, you can click below to register for our First, Do No Harm free webinar that will help you navigate what to do if one of your patients is living with an eating disorder.
