Why Your BMI Doesn't Reflect Your Wellness
I’m not sure about you, but I will never forget getting a BMI test done in elementary and middle school. Your physical education teacher breaks out the weird thing that pinches you (skinfold caliper) and you first get to see your total body fat. Then a weird steering wheel contraption is passed around, and you hold on to the handles as it calculates your BMI. Being someone who spent the entirety of life with one foot in the ‘normal’ category and one in the ‘overweight’ category, I fully understand that this post may be biased. In a different world, I may begin to discuss the scarring effect this classroom exercise had on young, teenage girls whose body image did not need any negative confirmation. Society does a perfectly fine job of pressuring women to be the next Kate Moss, and the supplementation of an unnecessary obsession over body fat percentage at the age of 12 is ridiculous. But alas, this is not that post.
I am here today to provide some insight into these tests; to provide knowledge that should be shared fully with those who are using the equipment to determine their fitness level. And here is what most PE teachers forget to tell their students: As with most things in life, the BMI calculator is flawed.
This should be a no brainer: the BMI test does not take age, gender, race, or muscle mass into the equation. Therefore a woman who has the same BMI as a man most likely has a higher body fat percentage, as an older woman has a higher body fat percentage than a younger woman. Being an athlete also throws the accuracy of the test off, as muscle weight may be mistaken for fat by the BMI test. It is common knowledge that muscle weighs more than fat, which explains why many athletes may actually test into the ‘overweight’ category despite excellent health.
Another issue is fluctuation of weight. It is completely normal for most people to have a small range of weights that fluctuate with food intake, hydration and activity levels. The test will tell a person who is 5’6” and 154 lbs that they are normal, whereas a person who is 5’6” and 155 lbs is overweight. Why does one pound of probable water weight make a difference?
BMI also doesn’t take your family history into consideration. It is important to consider genetics when determining your overall fitness level. Preexisting conditions such as thyroid disorder or disease can have an enormous impact on body fat percentage.
Although BMI is an excellent tool for determining the overall health of a large population quickly and easily, it should not be relied on to determine personal fitness and health. When you’re healthy, you should feel it more than see it as a number on some sketchy website calculator.
