Why it matters: Body fat, fat mass, and lean muscle mass
In ascertaining the status of your health and fitness, it’s often useful to use objective, measurable information and numbers. Certainly you have stepped on a scale to find out your weight, perhaps to see if and how much it has changed since you started a diet or personal fitness program. You’ve taken your temperature with a personal thermometer. Perhaps you’ve calculated your Body Mass Index (BMI).
We now have a DEXA scanner at Be Well that can generate a wealth of such useful and interesting information about your body.
For the body composition test, you just lie down on a padded examination table, and let the DEXA scanner do the rest. The scanner uses dual X-rays (a very, very low dose compared to a chest X-ray, mammogram, etc.) interpreted by complex computer software. It’s quick and there’s no discomfort.
So, what will you find out from a body composition test? The test results tell you your percent body fat, fat mass, and lean muscle mass, for your whole body but also broken down into regions of the body, including your trunk, right arm, left arm, right leg, and left leg.
Let’s say you’ve been on a diet for three months. A body composition test before and after will go beyond telling you how many pounds you’ve lost to reveal where you have lost the weight and how it has affected your percent of body fat. If you’ve been working out, you might find out that your arms have improved substantially in muscle mass but your legs are only minimally changed, which could give you some insight into how you might want to alter your exercise program. Or you might find that if you are right-handed, the arm and leg on your dominant side are in better shape than your left arm and leg, which again could lead to some changes in how you want to work your body when you exercise.
The information provided by a body composition test can also be relevant in the treatment of conditions such as AIDS/HIV, anorexia, and cystic fibrosis.
Your doctor will talk to you about your results, and about how they compare to guidelines. For example, an acceptable range of percentage of body fat is generally considered to be about 18%-28% for women and 10%-20% for men. (If you’re an athlete, it should be a bit lower.) If your results fall outside this range, this will be an opportunity to discuss what you need to do to address this and head off any adverse health consequences.