Thursday, May 24, 2012
I am fortunate to have, what I believe, is a very good doctor. So I was a little surprised some time ago to notice while waiting in her office (visits often involved a great deal of waiting) a posting of the Body Mass Index, or BMI, on the wall. I was even more shocked to find out that the BMI was incorporated into the clinic's electronic record keeping. The final blow came when the Doctor herself looked up my weight and height and issued a diagnosis to me in person.
The BMI originates from a statistical analysis performed almost 200 years ago (according to Jeremy Singer-Vine from the Slate) and updated in 1972 by a researcher named Ancel Keys. Keys wisely cautioned against using the results for individual diagnosis. So I supposed he was probably dismayed when the BMI started getting used for just this exact purpose by doctors everywhere.
So why use a flawed diagnostic like the BMI at all? Because it is cheap and easy, and the insurance industry will use any information that is cheap and easy, no matter how inaccurate. And once a practice gets ingrained in medicine, no matter how ill advised, it seems to stick around forever.
The good news is that there is growing evidence that using a combination of waist size and height can be turned into a useful index for individuals, and since waist size is almost as easy to measure as weight, perhaps we can finally say goodbye to the BMI.