In Part I, I covered some background on body composition “measurements” and talked a bit about two common techniques used in gyms and by fitness pros. In this segment, I want to address two other measurements that are typically assessed with and lumped into the body composition category but have absolutely NOTHING to do with body fat percentage.

Every body composition technique has one thing in common. And it is critical to understand why the methods I am talking about today do not have anything to do with body fat. Body composition assumes that an individual’s body is comprised of different types of tissue. It makes sense if you thing about it. We know, from like, second grade science class, that we have bones and muscle tissue and all of these different organs. Well, here’s the really important part, each of these tissues has a different density. If your recall for high school physics isn’t great, what that means is that each of these tissues contributes differently to our overall body weight. Denser tissues take up less space per pound. Guess what? Lean tissues (i.e. bones, organs, muscle) are usually pretty dense. And… for all my visual learners out there, five pounds each of fat and muscle….

This assumption of different tissue densities is what allows those “measurement” techniques I covered in Part I to guess at how much body fat you have. There are two measurements that are usually done in combo with either the skinfolds or the BIA that DO NOT make the different densities assumption. Because they don’t assume there is anything different about different tissues, these measurements are not actually giving an estimate of body fat percentage.

1. Circumferences or the Tape Measure Method. In this method, your fitness pro will use a soft tailor’s measuring tape to measure around certain body segments. The two most common are waist and hips. Since it usually accompanies the whole process of body composition it’s no wonder there is confusion. What these measurements are really able to do is give you information about your disease risk. The waist to hip ratio is an important indicator of your potential to develop cardiovascular disease as you age. That would be heart attack, stroke, PVD, and the like. Guys, you want your number to be under 0.96. Ladies, you are aiming for less than 0.85. Bigger numbers indicate that your body has a tendency to carry excess fat in your midsection, which we know is a risk factor for cardiovascular disease and certain cancers.
2. Body Mass Index or the It’s-Just-A-Height-Weight-Chart Method. In this method, you only need yourself, no fitness pro required. Seriously, just Google Body Mass Index and the chart will come up. Find your height, follow it across to your weight and the chart will give you a shiny number that represents your BMI. Less than 18.5 is underweight. 18.5-24.9 is ideal. 25-30 is overweight. Anything over 30 is considered obese. I know someone reading this is old wise enough to remember those insurance height-weight charts from the doctor’s office. This is the same thing, just with some fancy math to act as window dressings. As with the circumferences, BMI can give you an idea of your disease risk. More scientific studies than I have the energy to site here tell us that chances for developing everything from most types of cancer to rheumatoid arthritis goes up as your BMI increases.

And there you have it, folks. Circumferences and BMI can give us important indicator numbers regarding our health as we age, however; as with anything health related, keep in mind that one number doesn’t make or break. Regardless of your goals or training status, we are all works in progress and the more information you have to guide you the better.