The Truth About BMI
BMI has become a controversial topic in the health and wellness space, and for good reason. I'll share a quick breakdown on what it is, why it was created, and whether or not you should pay any attention to it.
What is BMI?
Body Mass Index (BMI) is a measure of body fat based on height and weight for adults. It's calculated by dividing weight in kilograms by the square of height in meters. You can find a plethora of free BMI calculators online like this one. BMI scores are then categorized ranging from underweight to severe obesity. BMI is used to estimate risk for some health conditions, such as heart disease. It is also used in creating public health policies.
Why was BMI created?
BMI's creation is traced back to the 19th century when Belgian mathematician Adolphe Quetelet developed a method to measure healthy weight in the general population. Quetelet’s formula was not initially intended to assess individual obesity but rather to provide a quick and easy way to measure obesity levels in a population for resource allocation purposes. Despite this intent, BMI gained popularity over time as a tool to assess individual weight status, and it's still used today by medical professionals.
Why is BMI problematic?
This could be an entire thesis, but I'll touch upon a few reasons why BMI is challenged as a useful tool today:
The underlying assumption of BMI is that weight increases in proportion to the square of height. However, this assumption is scientifically inaccurate and fails to account for important factors such as bone density and muscle mass. Bodybuilders, for example, would be classified as obese given their muscle mass.
BMI does not accurately reflect weight status in certain populations, such as older adults.
It was created based on caucasian male adults and therefore does not consider women, who naturally carry more body fat, and it also does not consider genetic differences among racial and ethnic groups.
Despite these well-recognized failings of BMI as a useful measure, it's used to determine healthcare policies and to determine how to allocate financial resources for healthcare.
Should you care about your BMI?
No. It is not a helpful or accurate determination of your body fat or your overall health or wellness. It is important to know about BMI and its limitations, though, as doctors still discuss it and use it as an indicator of risk for health conditions. Knowledge is power! Getting an annual physical and blood panel done are much more useful measures of your overall health and general good practice.
Reminder that no number can define you... not your age, weight, or BMI.
