I recently scandalized a dietician, when I confronted her with my assessment of the Body Mass Index (BMI), declaring it was a “tissue of lies.” She had no argument in its defense after I explained my position. I leave it up to the reader whether her silence was due to her politeness, professionalism or the patent indefensibility of the BMI.
Why do I assert the BMI is useless?
Let’s look at 3 points: history, application, and mathematics.
1) History – the BMI was originally developed by life insurance companies to fine tune their actuarial tables. The scale was created to measure the relative health of large population centers. It was NEVER meant to assess an individual’s health — and yet that is exactly what our ‘educated’ (read ‘indoctrinated’) medical community does. Our esteemed learned health professional community is using a sledgehammer where they should use a screwdriver.
2) Application – the BMI gives no additional useful information. If you’re above a certain number, your labeled as ‘obese’ by varying degrees. Regardless of the degree, unless you’re below the ‘healthy’ number, your health professional gives you the “Tsk-Tsk” lecture and a finger wagging you haven’t seen since your 3rd grade teacher.
The BMI data point is no more useful than simply setting a goal for your weight.
3) Mathematics – the BMI is based solely on your weight and a single physical dimension — height. Last time I checked, we are 3-dimensional creatures. It is obvious on the face of the argument that a person with a shallow chest and small shoulders should have a different measure of health than an NFL linebacker with a chest cavity the size of Montana. Taken to a ridiculous extreme, the BMI scale would have labeled Arnold Schwarzenegger at his peak as ‘morbidly obese’. Oh, please.
Other factors that have obvious ramifications for health, but are entirely ignored by the BMI, are age and gender. So if you can find a young male ballet trouper the same height and weight as my arthritic Aunt Abigail, you mean to tell me they have the same outlook as predicted by the BMI?
The BMI is the current standard merely because it’s cheaper to measure than other more accurate indices, like the Adipose Index or the Hydrostatic method, to name a few.
It’s time to punt the guilt-trip disguised as ‘best-practice’ called the BMI.
Tell your dietician I sent you.