Saturday, January 7, 2012

If not BMI then What Measurement Should You Use?

Many of us have heard about body mass index (BMI) and know that it uses height and weight in a formula (that was developed more than 150 years ago) and gives you an idea of where you are regarding your present body weight (i.e. ideal, overweight, obese etc.). BMI is a calculation that takes into account your height and weight but does not factor in body fat or more importantly lean tissue (muscle). This is why great athletes like Michael Jordan and many football players are considered overweight or even obese when their stats are entered into the following BMI calculation:

BMI = Body weight (lbs.) / Height(2) (inches) x 703

According to many government agencies like the CDC a healthy weight for someone in terms of BMI is about 18.5 to 24.9 - this means if you're over 25 your over weight. If your BMI is >30 your considered obese etc.

If lean mass and body fat are not calculated into the health equation then there is NO WAY it can be accurate, especially for individuals who carry more muscle. There is an abundance of research that shows someone with a BMI >25 is not necessarily less healthy than someone with a BMI between the 18.5 - 24.9 range.

How do you determine then if the weight that you currently see when you step on your bathroom scale is accurate? You don't - you don't make your bathroom scale the be all end all number, especially since it can't differentiate between the ratio of muscle and fat. Maybe you start to use it as part of your personal health index and add a waist-to-hip ratio (a waist/hip measurement) and a %body fat score into the mix.  Start paying more attention to ratio of muscle to fat that your carrying on that body of yours. There are many ways to determine %body fat (Skinfolds, BIA, TOBEC, DEXA, Hydrostatic weighing, etc.) but the least expensive method is skinfold calipers.  If you're unable to use any of those methods then take a simple measurement around your waist. This does not determine body fat but it can tell you a great deal.  Men should not exceed 40 inches and women 35 inches in regard to a waist measurement.  Are you starting to get the picture?

Bottom line - it's not about a number - one number like BMI alone or what your bathroom scale tells you should not define who you are. Start paying more attention to the amount of muscle tissue your body'll be much better of as you age!

Here is a good book to read if your looking to see from a research standpoint why BMI is not as accurate  as many believe - The Obesity Myth by Paul Campos.


Ann Collins said...

Michael, it would be great if Kokofit provided some lean body mass testing. Perhaps at the end of a program. I sure would have loved that measurements now that I am down 60 lbs!

Michael Wood said...

Hi Ann - at this time Koko does not but I can tell you we are working on something that would allow members to do just what you asked. Fantastic job by the way with your weight loss!!!