If you’ve been around the Charleston and Mount Pleasant fitness scene long enough (or even if you just pay attention to your doctor), you’ve heard of it. Body Mass Index: that special number that is supposed to sum up your overall wellness level in a couple of digits. According to the Centers for Disease Control, “BMI is a person’s weight in kilograms divided by the square of height in meters.” It goes on to say that while BMI doesn’t measure body fat directly, it loosely correlates with other types of measures of body fat (things like skin fold thickness measurements, underwater weighing, etc.). And while it’s not as precise as these more scientific ways of measuring body fat, “BMI is an inexpensive and easy-to-perform method of screening for weight category, for example underweight, normal or healthy weight, overweight, and obesity.”
So to simplify, measuring BMI is a quick and easy screening tool doctors and scientists use to see if individuals fit into a healthy “range”. According to Harvard School of Public Health, many health professionals start with BMI when assessing their patients. “Research has shown that BMI is strongly correlated with the gold-standard methods for measuring body fat. And it is an easy way for clinicians to screen who might be at greater risk of health problems due to their weight.”
WHAT DO BMI NUMBERS MEAN?
HSPS continues, “The World Health Organization states that for adults, the healthy range for BMI is between 18.5 and 24.9. Overweight is defined as a body mass index of 25 to 29.9, and obesity is defined as a body mass index of 30 or higher. These BMI cut points in adults are the same for men and women, regardless of their age.”
BUT IT’S NOT ALL IN A NUMBER
But before you start panicking over your number, please keep in mind that BMI is just that—a number. National Public Radio’s math expert and Stanford University Professor Keith Devlin is explicit in his distain for relying on BMI to determine health: “It makes no allowance for the relative proportions of bone, muscle and fat in the body. But bone is denser than muscle and twice as dense as fat, so a person with strong bones, good muscle tone and low fat will have a high BMI. Thus, athletes and fit, health-conscious movie stars who work out a lot tend to find themselves classified as overweight or even obese.”
Case in point: Men’s Health Magazine has uncovered that muscle-bound Duane “The Rock” Johnson “has a body-mass index, or BMI, of 34.3. Which means, according to U.S. government standards, the Rock is obese.” And his ripped costar Vin Diesel? “…at 27.1, is overweight.”
Health Magazine lists other svelte celebrities that fall into the overweight to obese categories including Tony Romo (at 28.8), Arnold Schwarzenegger (30.8) and Tom Cruise (26). And guess what? Even super-fit gym owner Andrew Duffy falls into the BMI category of “obese” if you just look at the numbers!
WHY BMI CAN BE MISLEADING
While the US Government is still using BMI as a health measurement, much research has come out about how inaccurate these numbers really are. According to Time Magazine, “For years, scientists have said that BMI can’t distinguish between fat and muscle, which tends to be heavier and can tip more toned individuals into overweight status, even if their fat levels are low.
“In the journal Science, the latest data from University of Pennsylvania shows that BMI also doesn’t tease apart different types of fat, each of which can have different metabolic effects on health.” So while a BMI number may read relatively low, it doesn’t take into account WHERE the fat in the body is, and what type of fat is distributed. “Even relatively thin people can have high levels of visceral fat, which means they might be considered healthy by BMI standards, but internally they may actually be at higher risk of developing health problems related to weigh gain.”
And on the contrary, according to Medical Daily, “Nearly half of those whose BMIs labeled them as overweight were actually healthy, according to data on their other health measures. Fifteen percent of those who were classified as obese were also considered healthy.”
Instead of relying on BMI, many trainers and fitness experts (including those at DUFF) measure body fat percentage. According to LiveStrong, this is much more useful to clients, especially if they are athletic or physically active. “In the long term, body fat percentage will be the best gauge of your health and fitness….If you are an athlete or active, you are going to have more weight in muscle than the average person, and your BMI may not accurately reflect your health and fitness, or how healthy and fit you look.”
We at DUFF will generally use a biometrical impedance analysis tool (that two-handled device we have you squeeze when we’re doing our initial weigh-in and measurements). We track your body fat numbers generally with the goal of reducing your body fat percentage through cardio exercise, weight training and diet management. This is a good tool for us to gage how effective the workout plan is. It’s our goal to get our clients into the “healthy range” of body fat percentage (these numbers will vary depending on whether you are male, female or an athlete. To see a BF percentage chart click HERE).
NUMBERS AREN’T EVERYTHING
Of course, just like with BMI, your body fat percentage is just a number. The greatest indicator of health is getting out and living a healthy lifestyle, spending time with your trainers at the gym, getting in lots of cardio, great nutrition and reasonable amounts of rest. If you do all of these things, you will transcend the numbers and be out there living the healthiest life for YOU!