Why BMI is not a smart health measurement for teachers

**The Edvocate is pleased to publish guest posts as way to fuel important conversations surrounding P-20 education in America. The opinions contained within guest posts are those of the authors and do not necessarily reflect the official opinion of The Edvocate or Dr. Matthew Lynch.**

Guest post by Rick Osbourne

Anyone familiar with Operation Pull Your Own Weight already knows we contend that using BMI as the measurement tool of choice represents a major obstacle when it comes to making any progress on the ongoing obesity epidemic. I’ve personally railed against BMI on one too many occasions – particularly when it relates to kids.

But I recently received an email from a friend named Dr. Wayne Wescott of Quincy College in Quincy, MA which made the case against BMI when used on adults so eloquently that I thought our readers would find it compelling. Allow me to quote Dr. Wescott:

“Take for example a 65 year old male who has performed no resistance training and weighs the same 165 pounds that he did at age 25. Of course his BMI would be the same and his physician would say that he’s in great shape. However, his body composition has actually changed by at least 50 pounds (25 pounds less muscle – at 6 pounds/decade reduction rate from sarcopenia – and 25 pounds more fat).”

Let’s dig into this example a little deeper just for fun. Let’s say this male teacher’s percentage of body fat was 20% back when he was 25 years old. That means 33 of his 165 pounds of body weight was made up of fat back then (165 lbs. X .20 = 33 lbs.). So he’s in pretty good shape.

Four Decades Later…
Now as Wescott suggests, let’s flip the calendar ahead forty years and see that this teacher’s body weight is still the same 165 pounds. And his height is also the same. That means his BMI will be exactly the same at age 65 as it was when he was age 25. No change at all!

But now we learn that this gent has done no resistance training during those four decades. This means he’s lost a bunch of muscle mass (approximately 25 pounds, at six pounds per decade due to sarcopenia). In order to weigh the same 165 pounds he’s replaced the lost 25 pounds of muscle mass with 25 pounds of body fat. That’s the only possibility.

That means at age 65 this gent now carries 58 pounds of body fat instead of the original 33 pounds of body fat (33 + 25 = 58). Since his body weight remains exactly the same, 165 pounds, his actual percentage of body fat has now ballooned from the original 20% to over 35% (58/165 = 35%). In other words, he’s actually gone from being in pretty good shape at age 25, to being OBESE (30% body fat or higher) at age 65…despite what his BMI indicates.

A HUGE Discrepancy!

Let me say it this way. That’s no small discrepancy! That’s a huge discrepancy!! This guy is now carrying 25 MORE POUNDS OF BODY FAT and he has 25 FEWER POUNDS OF MUSCLE MASS (horsepower) with which to carry it. To make matters even worse, this 25 pounds of muscle mass loss has caused his metabolism (his ability to burn calories) to drop like a rock. That means in order to maintain his 165 pounds, he can’t eat as much as he used to eat.

Is it any wonder this guy can no longer get up and down a flight of stairs the way he could when he was 25? He can’t run, jump, climb, or do anything with the same efficiency as he was able to do forty years ago. Yet BMI DETECTS NO DIFFERENCE AT ALL!!! *

The big question in the minds of many of us non-bureaucrats out here on Main Street is how in the world can anyone expect to make any progress on the obesity epidemic if the powers that be continue to endorse a measurement tool that’s unable to distinguish ten pounds of body fat from ten pounds of muscle mass from ten pounds of dog food, or bubble gum?

You may as well attempt to play the Super Bowl without any yard lines on the field, and a game clock that doesn’t work. If we’re unable to measure changes accurately and we continue to do nothing about it, why don’t we just confess out loud that we really don’t give a damn about beating the obesity epidemic? After all, many major corporations are making boatloads of profit because of the epidemic. And the bottom line after all…is the bottom line.

*There is a cost effective alternative known as a FORE Score (Functional Obesity Risk Evaluation Score) in case anyone is actually interested in accurate body comp measurement without breaking the bank.

**UCLA recently published a longitudinal study of over 40,000 people which is described by its author, Dr. Janet Tomiyama as “The final nail in the coffin of BMI.” This development certainly represents a step in the right direction.


Rick Osbourne is a former physical educator and a pioneer in the field of functional childhood obesity prevention. He currently serves as President of the Pull Your Own Weight Foundation which is an Illinois based, 501c3, not for profit organization whose focus is functional childhood obesity prevention. He’s written and published three books in this field, the latest of which is entitled Beating Childhood Obesity Now: A Simple Solution for Parents and Educators. He’s the Examiner’s national childhood obesity prevention correspondent. He writes an online column for The Edvocate. And you can connect with Rick via TwitterLinkedin, or Facebook.

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