Can we talk about what BMI ACTUALLY is?
I feel one of my "actual science" rants coming on.....
Everyone and their freaking insurance agent is talking about the BMI measurement as though it's some brilliant calculation that can illustrate clearly how healthy an individual is. One of the things that makes me bug-nuts about this current popular chatter is that most people have little to no actual understanding of what BMI is, but it's discussed like it's some holy number. So, I'm going to talk about this.
BMI stands for Body Mass Index, and it was invented in the 1800’s by a Belgian intelectual named Adolphe Quetelet who was doing social research on what the “average man” looked like. His intent with this number was to get a snapshot average of body types across large numbers of people in a population. It is not designed to look at differences, or even at individuals. Then in 1972 a professor and researcher named Ancel Keys published a paper called “Indices of Relative Weight and Obesity.” In it, he examined height-weight formulas and he made the determination that Quetelet’s was the best. Keys also gave Quetelet’s formula the name “body mass index” and actually warned in his paper against using BMI for individuals diagnoses, since the equation ignores a lot of other variables.
These days, most folks go to one of the online BMI Calculators and plug their height and weight into it, and voila, magic number. But there is actually a mathematical formula behind that magic. The formula was originally developed in metric units and is: (Weight in Kilograms / (Height in Meters x Height in Meters)) and more recently has been converted into English units: ((Weight in Pounds / ( Height in inches x Height in inches)) x 703). As you can see, the formula doesn't take into account anything like your body frame, the amount of muscle on your body, the density of your bones, how you carry your weight, whether you exercise etc... Heck, it doesn't even take gender into account, and male and female bodies are designed to include vastly different amounts of fat. All the things that Keys warned about it not taking into account.
So why the heck is it being used so often as a measurement for health these days? Insurance companies. Seriously. In the early 1900’s, motivated by their bottom line, life insurance companies started doing studies of BMI in an effort to show that overweight people were more likely to have health problems and die earlier, this way they had official looking numbers to show their policy holders, to justify raising premiums and denying claims. OK, but that doesn't really explain why so many doctors use it. While that began with the influence by insurance companies to provide this magic number on patients, according to the "Centers for Disease Control and Prevention", it’s primarily used in the medical field because its easier and less expensive than better alternatives. SERIOUSLY. Easier and less expensive. (you can see those words on their very own website here: http://www.cdc.gov/healthyweight/assessing/bmi/adult_bmi/index.html#Why)
Our physical well being as a society, our individual self images in many cases (and therefor our mental health) is being significantly harmed by the misplaced dependance on BMI as a measurement for health. It's being used as a reason to deny health coverage, or to price it so that individuals have no choice but to choose inferior health coverage, it's result is being used as a determining factor in diagnosis, and quite frankly it's lazy, ineffective healthcare.
It doesn't only harm those of us who's BMI would place us in the "overweight" or even "underweight" category. We've become so dependent on classifying people's health based on their BMI number that when someone who's BMI is in the normal range presents with symptoms like body pain, tests are often never even considered for illnesses that have been classified as obesity diseases. Like my neighbor: young, active, normal range BMI. Who over a year's worth of doctors visits got a diagnosis of Fibromyalgia and then one night ended up in the ER having her chest cracked to drain massive amounts of fluid from around her heart. - they never even considered running any of those sorts of tests because her BMI didn't indicate it to be necessary. Which is the explaination her doctors actually gave to her furious and freaked out husband.
So maybe, just maybe, we should consider not using BMI for anything other than what it was intended - averaging body size data for large groups of people for social research.