The Problem With BMI

Does this person look overweight to you? Well, according to the Body Mass Index chart (BMI) most commonly used today, he is.

Colby has been working at a Koko FitClub as a FitCoach for just over a year and is an impressive specimen of fitness. He has a body fat percentage of around 12% with a 31-inch waist. He can bench press 315 lbs, deadlift 405 lbs, and, in a recent contest we held at the club, he banged out 147 push-ups in 3 minutes. He has lifted more than 40,000 pounds in a single 30-minute Koko strength session, a remarkable feat.

Pretty good stats. Yet, according to the traditional BMI chart, Colby is “unhealthy.” At 5’10” and 190 lbs, his BMI is 27, which puts him squarely in the BMI chart’s “overweight” category.

How could this be? Very simple: BMI is based solely on Colby’s height and weight, and it doesn’t take into account body type or composition. Colby carries a lot more muscle on his frame than the average 190-pound person. Another 5’10” 190-pound person might have much lower muscle mass, and a much higher percentage of body fat, but be classified in exactly the same place on the BMI chart.

BMI gives an incomplete picture of our health, and this can have real-world consequences. Colby works by day as an engineer, and his employer offers a discount on employee contributions to the company health-insurance plan for those who maintain a high level of health. One of the criteria they use is BMI. Because Colby falls into the “overweight” range, he was denied the discount. Instead of being rewarded for his fitness, he was penalized.

Meanwhile, someone 10 pounds lighter, but with a much higher percentage of body fat and lower level of muscle, could be rewarded with that insurance discount, despite potentially being much less healthy and at higher risk for disease.

This doesn’t make much sense. A new study from UCLA published in the American Journal of Medicine supports the notion that using BMI to measure health is the wrong idea. The researchers measured body composition for a group of 3,659 men and women; men over 55 and women over 65. They used bio-impedance, the same technology employed at Koko’s FitCheck measuring station to determine muscle mass and other biomarkers.

The study’s measurements took place between 1988 and 1994, plus a follow-up survey conducted in 2004 to check the mortality rates of the subjects. The researchers found that mortality was much lower in the quarter of participants with the highest muscle mass, compared with the quarter with the lowest muscle mass.

“In other words, the greater your muscle mass, the lower your risk of death,” said Dr. Arun Karlamangla, an associate professor in the geriatrics division at UCLA’s Geffen School and the study’s co-author. “Thus, rather than worrying about weight or body mass index, we should be trying to maximize and maintain muscle mass.”

The study focused on older adults, so Colby, at 26 years old, wouldn’t have qualified. But there is ample reason to believe that the findings would apply to individuals of all ages.

As a personal trainer who has worked with people of all different body types, I understand the value and importance of body composition. If we’re going to build a healthier society, businesses and other organizations should be embracing this concept.

There are challenges in shifting the paradigm, primarily because there is no perfect way to measure body composition. Technology is making advances including the bio-impedance method that is the basis of Koko’s eBMI measurement (our more precise alternative to BMI). But hydration levels, the foods we eat, and time of day can all effect the measurement. Even hydro-static weighing, which many consider the gold standard of body comp measurement, is far from ideal.

As innovation continues and our knowledge of our bodies increases, I’m optimistic a day will arrive when we can analyze our fitness with greater precision, and people like Colby will be recognized as health trailblazers and role models.
Michael Wood, CSCS
Chief Fitness Officer, Koko FitClub


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About Michael Wood, Chief Fitness Officer
Michael Wood, CSCS, is Chief Fitness Officer at Koko FitClub, driving the development of integrated strength and cardio training and nutrition programs for Koko members nationwide. A nationally acclaimed fitness expert, Michael has conducted research as a Senior Exercise Physiologist at the Nutrition, Exercise Physiology and Sarcopenia Laboratory at the Research Center on Aging at Tufts University, and has lectured at Boston University and the University of Connecticut. He has been named Boston Magazine’s “Best of Boston” Personal Trainer, and made the Men’s Journal “Dream Team” list of the nine best trainers in the U.S. Michael and his family live in North Attleboro, MA.

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