I was recently at the doctor for my yearly checkup and was horrified to find out that doctors are still relying so heavily on BMI to determine the “healthiness” of, or a “healthy weight” for, an individual. More specifically my doctor used the height-to-weight calculation to determine my BMI. This formula is a calculation that is nearly 200 years old and was designed to be an easy way to determine if a person was at a healthy weight. In the late 1830’s, there were not nearly as many overweight, obese, or unhealthy, sedentary people as there are today, nor were there professional athletes, body builders, or others who might have a high ratio of lean muscle to body fat, so this was a generally accurate means of determining one’s health.
The formula to determine one’s BMI by using height and weight calls for converting the person’s weight from pounds to kilograms (divide weight in pounds by 2.2) and divide that number by their height in squared meters (multiply height in inches by 2.54, divide by 100, and square the number). For example, my weight at the doctor was 122 pounds (converts to 54.5 kg), and my height is 60 inches (converts to 2.32 meters squared). By doing the math, this makes my BMI 23.5, and a BMI higher than 24.9 is considered obese….. To look at me, you would know that I am not 8 pounds (or 1.5 points on the BMI scale) from being obese.
The fact is that I lift weights three days a week and I do medium intensity to strenuous cardio two to five days a week. As most of us know, lifting weights increases muscle mass, and muscle weighs more than fat. Therefore someone of the same height and weight as me but who does not lift weights would likely have a higher body fat content than I, but by using the height-to-weight calculation would have the same BMI that I have. There are other much more accurate ways to determine BMI, but these ways take more time, money, and knowledge.
Research shows that the most accurate way to determine a person’s BMI is by using the hydrostatic weighing method, where a person is weighed on dry land before being submerged into water and being weighed on a special scale. The person’s underwater weight provides the most accurate method of determining body composition, as a person with more lean muscle mass will weigh more under water than a person with more body fat. This is because fat floats under water and muscle sinks. Other methods, which are less accurate than hydrostatic weighing but much more effective than using the traditional BMI calculation, include skin caliper, tape measure, air displacement plethysmography, and bioelectrical impedance analysis.
It is sad to see physicians still relying on this very outdated method, but it also poses concern to those who may be dealing with body dysmorphic disorder. It was bothersome enough to be told that I was not far from being considered “obese” and asked if I exercise regularly (uh, yeah, I do), but to a person with body dysmorphic disorder or an exercise addiction, this could be detrimental.
Think positive, stay active, and smile. -A
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