5 Ways to Measure Body Composition

We hear the same messages all the time! Take this pill and lose 10 lbs fast. Start a new diet and transform your life today. 

In the real world, your body is a masterpiece. So many people will tell you what to do with your own body. But what you really need to understand is this: you're in control. You get to decide when and how to lose weight, or when and how to gain weight. And it all starts with understanding body composition.

What is body composition?

Body composition consists of two separate measurements: fat, and fat-free mass (FFM). Weighing yourself on the scale will not tell you your body composition because the body is made up of multiple elements. Bones, tissues, muscles, and organs are all small parts of the whole. FFM is everything but fat but mainly focuses on muscle content.

Why does body composition matter?

Body composition matters because it separates the fat from the fat-free mass and tells you your estimated healthy body fat percentage. Healthy body fat percentages vary by age, gender, and population (Scott, 2020). Healthy body fat percentages for men range from 10%-22%, while healthy percentages for women range from 12-33% (Lohman, Houtkooper, and Going, 1997).

Having too much body fat puts you at a higher risk for developing diseases like hypertension, diabetes, and obesity. Conversely, malnutrition leads to abnormal growth rates and muscle wasting.

5 ways to measure body composition.

Body composition measurements help you estimate a healthy weight, track growth and monitor how well your overall program is working. Here are just a few ways you can measure body composition:

1. Air Displacement Plethysmography (ADP): ADP requires patients to enter a closed pod in order to calculate body composition. The amount of air in the pod is measured before the client enters and while the client sits in the front chamber by the diaphragm. Body volume can then be calculated by the difference of tare weight versus the weight of the first chamber when the client is in it (Gibson, 2018).

2. Hydrostatic weighing (HW): HW estimates body volume (BV) by having clients fully submerge themselves in a tub of water while sitting on a chair scale. Disadvantages to this method include errors in measuring residual volume (the amount of air left in the lungs after maximal exhalation). Morrow et al. (1986) found that miscalculations in RV lead to bloated body fat measurements (+2.8% to 3.7% BF). Advantages include the ability to weigh almost any body type and accuracy of results when common testing errors are controlled for.

3. Dual-energy x-ray absorptiometry (DXA): In DXA, the patient lies flat on a scanner bed while an x-ray machine takes measurements of the entire body. This is often used in clinical settings to diagnose osteoporosis. Advantages of this method include extreme accuracy for many body types. Disadvantages include variations between models and algorithms used (Genton et al. 2002). 

4. Bioelectrical impedance (BIA): BIA measures body composition by resistance to an electrical current that is passed through the client's body. In theory, body fat is not a good conductor of electrical energy. Individuals with higher body fat levels will have more resistance to current, while those with less body fat will have less resistance to current. Advantages include ease of use, little setup, and great for large population studies. Disadvantages include deviations in measurements across different devices and hydration status affecting accuracy (Graves et al. 1989; Jackson et al. 1988).

5. Skinfolds (SKF): In SKF assessments, body composition is measured by using calipers at different sites across the body: chest, subscapular, midaxillary, suprailiac, abdominal, tricep, bicep, thigh, or calf. The calipers indirectly measure the thickness of fatty tissue. Advantages of this method include cost and quick set up. Disadvantages include the amount of skill required to take accurate readings and selecting the right equation across different populations.

Final thoughts.

Tracking body composition is a fantastic way to gauge how well your fitness and nutrition programs are working for you. Some of these methods like DXA and HW may not be readily available to you. BIA and SKF are great alternatives to lab tests that can be completed at home. 

The important part is to stick with the same test and tools used to take the test over time.

SOURCES

1. Gibson, A. L., Wagner, D., & Heyward, V. (2018). Advanced Fitness Assessment and Exercise Prescription, 8E. Human kinetics.
2. Graves, J. E., Pollock, M. L., Colvin, A. B., Van Loan, M., & Lohman, T. G. (1989). Comparison of different bioelectrical impedance analyzers in the prediction of body composition. American Journal of Human Biology, 1(5), 603-611.
3. Jackson, A. S., Pollock, M. L., Graves, J. E., & Mahar, M. T. (1988). Reliability and validity of bioelectrical impedance in determining body composition. Journal of Applied Physiology, 64(2), 529-534.
4. Lobman, T. G., Houtkooper, L., & Going, S. B. (1997). Body fat measurement goes high-tech: not all are created equal. ACSM's Health & Fitness Journal, 1(1), 30-35.
5. Morrow, J. J., Jackson, A. S., Bradley, P. W., & Hartung, G. H. (1986). Accuracy of measured and predicted residual lung volume on body density measurement. Medicine and science in sports and exercise, 18(6), 647-652.
6. Scott, J. R. (2020, January 6). Do You Know Your Body Fat Percent? Retrieved March 19, 2020, from https://www.verywellfit.com/what-is-body-composition-3495614