I have been training clients since 2002 at MVP Sports Center & Physical Therapy. Through these years I have had one issue that transcends every type of client. That issue is the concept of being overweight. The official definition from the Center for Disease Control is as follows: “Overweight and obesity are both labels for ranges of weight that are greater than what is generally considered healthy for a given height. The terms also identify ranges of weight that have been shown to increase the likelihood of certain diseases and other health problems.” According to the CDC, the way to find out if you’re overweight or obese is to use the BMI equation. The actual equation for calculating your BMI is as follows: (weight (lb) / [height (in)]2 x 703) . I invite the three people who may read this to plug their information into this equation. Now after all the nasty mathematics, we can see where we fall in the BMI tables:
Below 18.5-Underweight: 18.5 – 24.9-Normal Weight: 25.0 – 29.9 Overweight: 30.0 and Above Obese.
Now, before we go and get all depressed and angry about the results, let’s look at the wonderful equation that got us here. I have several problems with this equation, but here are my main three:
- The validity of the equation is questionable at best. The variables measured are height and weight. The end result is the ratio between the two. NO ACTUAL FAT MEASURED! If excess fat is the problem, that leads to certain diseases and health problems – let’s get that measured then. People, please find your local certified fitness professional (ME!!) and get your body composition measured.
- There are some important variables left out of this equation. Both age and gender are not accounted for in this equation. These are important factors that play into someone’s ability to store and utilize fat. The Mayo Clinic College of Medicine did a recent study in 2008 looking into the accuracy of the BMI equation and their conclusions are as follows. “The accuracy of BMI in diagnosing obesity is limited, particularly for individuals in the intermediate BMI ranges, in men and in the elderly. A BMI cutoff of> or =30 kg m (-2) has good specificity but misses more than half of people with excess fat. These results may help to explain the unexpected better survival in overweight/mild obese patients.” With this being said, the BMI is not too favorable to us men and our older population.
- Lastly, my favorite characteristic of the BMI is the age of the equation. A Belgian mathematician and sociologist named Adolphe Quetelet created the Body Mass Index between 1830 and 1850. He did this as a way to compare a person’s height with their weight. This technique was originally meant to aid in social science education, and wasn’t intended to determine obesity levels. This equation may have been cutting edge at the time, but I don’t think anyone wants to be told they are at risk for health problems based on an equation that pre-dates the Civil War. There have been a few technological advances since 1830 (airplanes, space shuttles, Nintendo Wii etc.), yet we still utilize this outdated technique. Yes, the BMI is easy to use and anyone with a calculator and a middle school IQ can figure it out, but anything worth anything takes some thought.
So in conclusion, when the Wii Fit uses this equation and your person on the screen looks chunky, don’t worry. Don’t get me wrong, I agree that Americans need more exercise, activity and nutritional advice, but I disagree on how we are assessing the issue. Let’s all just come to MVP Sports Centers & Physical Therapy in Lake Forest, get a true fitness assessment, sign up for lots of training and help me get some more job security!
By Coach Wray Watkins, BS, CSCS
Director of Strength & ConditioningShare