The next time you happen to catch a Minnesota Vikings game, take a look at¬† Adrian Peterson, the team’s 6’1, 217-pound running back. Now ask yourself: what¬† kind of physical characteristics would you attribute to him? Athletic? Lean?¬† Fit? All of these certainly sound like valid answers to us‚ÄĒbut his clinical¬† classification might surprise you.
By any normal standards, Peterson is¬† one of the fittest men on the planet. But by our country’s system of measuring¬† body fat, he’s overweight. If you’re like most people, you’ve probably heard of¬† the ‘body mass index,’ or, as it’s more informally known, BMI. It’s a popular¬† formula used to not only gauge if a person is overweight or obese, but also how¬† great their risk is for future health problems.
BMI is a relatively¬† straight
forward equation that measures a person’s body fat by comparing their¬† weight to their height:
(Weight in pounds) / (Height in inches) (Height¬† in inches) x 703
You can also figure out your BMI without doing any math,¬† here: Log onto http://nhlbisupport.com/bmi/ for an online¬† calculator.
There are four different categories a person can fall into,¬† ranging from underweight to obese. They are:
*18.4 or lower:¬† Underweight. *18.5 to 24.9: Normal weight. *25 to 29.9: Overweight. *30¬† or higher: Obese.
According to the National Institutes of Health, being¬† overweight or obese by this measure can put you at risk for heart disease, type¬† II diabetes, and even some cancers.
But BMI doesn’t work well for¬† individual people. One of the formula’s obvious flaws, explains Alan Aragon, the Men’s Health Weight Loss Coach and a nutritionist in California, is¬† that it has no way of discriminating between fat and muscle‚ÄĒwhich is the case¬† with Peterson.
Part of the problem is that BMI was never designed as a¬† tool for judging any individual person’s weight‚ÄĒeither by physicians or the¬† general public, says Timothy Church, a professor of health at Pennington¬† Biomedical Research Center. In fact, the formula was originally intended to¬† measure the collective weight of an entire population, but because of its¬† straightforward math and distinctive categories (i.e., if you score a 25 on the¬† BMI scale, you’re overweight), it soon also took off.
Here’s how BMI was¬† born: In the early part of the 20th century, medical studies began to show a¬† link between excess weight and an early death. So doctors and insurance¬† companies started to seek out an easy method to determine a person’s body-fat¬† percentage. Insurance companies were especially concerned with this task, and¬† devoted portions of their budget to discovering an obesity-determining¬† calculation.
It wasn’t, however, until physiology researcher Ancel Keys¬† published a study in 1972 called “Indices of Relative Weight and Obesity,” that¬† the modern version of BMI came about. Keys conducted a series of studies on male¬† populations in order to test if any pre-existing mathematical equations could¬† measure a group’s relative amount of body-fat. Fortunately for him, one did. The¬† “Quetelet Index,” (a.k.a., weight divided by height, squared) which was¬† developed by Belgian statistician Adolphe Quetelet in the mid-1800s, proved to¬† be successful.
To Keys’ credit, he never intended for physicians or¬† insurance companies to use this equation‚ÄĒbut BMI was just too perfect. Because¬† it was simply a math equation, it was quicker, easier, and cheaper to use than¬† more direct and accurate measures‚ÄĒlike the underwater weighing test, which¬† measures how much you weigh by how much water you displace, and the skin fold¬† measurements, which calculates how much fat you have beneath your¬† skin.
“BMI was really pushed by [companies like] Metropolitan Life,”¬† Church said. “It was meant to give them an excuse to charge [their clients]¬† more.”
The formula received its official stamp of approval in 1985, when¬† the NIH cited it as the index of obesity, Ever since then, BMI has gradually¬† become more and more accepted‚ÄĒnow it’s the standard, go-to formula for¬† determining what makes a healthy weight, even among regular people, says Frank¬† Hu, Ph.D., professor of health and nutrition at the Harvard School for Public¬† Health.
Another issue is gender. The Quetelet Index‚ÄĒand corresponding¬† Keys study‚ÄĒwere both created from research on male populations. An entirely¬† different formula was originally used for determining obesity in female¬† populations, and yet, doctors use the same equation for both genders, says¬† Church. In the beginning, the NIH differentiated between men and women by¬† establishing different “thresholds” for one’s BMI, to account for the variance¬† between men and women in the equation. But even that difference dissolved in¬† 1998. When pressed for the reasons why, an NIH spokesperson declined to¬† comment.
So why has no one tried to change the system? One reason is that¬† imprecise numbers from BMI aren’t dangerous, says Hu. And besides, doctors are¬† able to determine risk factors using other measurements.
Still, the¬† alternatives to BMI aren’t perfect either. The most common of which is the waist¬† circumference test, which measures abdominal obesity (a.k.a., the fat around¬† your stomach). It’s slightly better than BMI at measuring someone’s risk for¬† illnesses like heart disease and diabetes, say our experts, because it measures¬† fat specifically, instead of taking into account the weight of a person’s muscle¬† mass.
The truth is, people know if they’re overweight‚ÄĒso be your own¬† judge. Look in the mirror, monitor your jean size, and talk to your doctor. But¬† don’t rely on a flawed formula to determine your health status.
Read more at Men’s Health: http://www.menshealth.com/weight-loss/truth-about-bmi?cm_mmc=BONL-_-815722-_-02152012-_-dek#ixzz1mYwOuiPX