Body Mass Index (BMI) is a popular measurement tool that measures body fat. Said to estimate your level of obesity by dividing your weight (in kilograms) by your height in (meters squared), it’s perhaps not all that surprising that there have been many holes found in this method. When it comes to a healthy weight, here’s why BMI’s are a busted measure.
Factors Missed by BMI
It’s difficult to place a “one size fits all” measurement tool across a wide spectrum of people (we come in all shapes and sizes, don't you know?!) and expect that it will render accurate results for each. This is just what BMI does, but unfortunately it’s missing highly relatable factors to body weight, including race, sex, bone density, muscle mass and overall body composition.
This means that a person, such as an athlete, with strong bones and developed muscle mass, may easily have a BMI that classifies as high. A 2005 study found that, “BMI frequently classified muscular individuals who did not have high skinfold measurements as overweight or obese.” It also ignores waist size, which is perhaps the clearest indicator of obesity levels.
An Outdated Tool
Discovered in the early 19th century by mathematician Lambert Adolphe Jacques Quetelet, BMI is now an outdated, mathematical formula that was initially used to measure the obesity of the general population for government uses in allocating resources. More effective for measuring the body fat of the “average man,” BMI fails frequently when applied to highly active individuals as well as naturally lean and fit people.
A Busted Formula
Some researchers believe that BMI is based on a busted formula that leads to confusion—which divides weight by too much in short individuals and too little in tall people. The perhaps over-simplified formula (which was created when computers didn’t exist) results in shorter people believing they’re thinner and taller people believing they’re bigger—without taking in any other factors.
Discovering Your Healthy Body Weight
By adding in waist measurements, a determining factor left out completely by BMI, you’re much more likely to arrive at a healthy body weight for you. According to a recent study, “Waist measures appear to be important discriminating measurements when assessing lipid and blood pressure measurements in adolescents with high BMI and should be included when screening for cardiometabolic risk in overweight and obese adolescents." Waist measurement includes both waist circumference and waist-to-height ratio.
Taking all of this into account, it’s clear that there are more fruitful and accurate ways to approach and measure body health. Instead of focussing on BMI, focus on staying active and eating well—both of which are the keys to good health and wellbeing. Perhaps when we think of BMI, we should think “Busted Measure, Indeed.”