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What is body composition?


Updated May 30, 2014

Woman measuring percentage of body fat on waist
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Body composition is the body’s relative amount of fat to fat-free mass. Those with optimal body composition are typically healthier, move more easily and efficiently, and in general, feel better than those with less-than-ideal body composition. If you can achieve a better body composition goes a long way toward improving your quality of life and overall wellness.

Body composition is divided into two separate types of mass: fat-free mass -- which is comprised of all of the body’s non-fat tissues -- and body fat. Fat-free mass includes bone, water, muscle, and tissues. Body fat is literally fat located within the body. Some fat is necessary for overall health; it helps protect internal organs, provides energy and regulates hormones that perform various functions in body regulation. However, when someone is overweight or obese, they have an excessive accumulation of body fat.

Body fat includes essential fats, such as lipids, and nonessential body fats; these fats make up around five percent of total body weight for men, and up to 12 percent for women. Nonessential fat is found mainly within fat cells and adipose tissue, below the skin and surrounding major organs. The amount of nonessential fat stored in the body is variable among individuals on factors such as age, gender, and diet. Excess nonessential fat can normally be attributed to consuming more food energy than what is burned through metabolic functions and activity.

Body fat percentage is the percentage of total body weight that is comprised of fat. Decreasing your body fat percentage, if it is too high, isn’t just about improving your appearance. A high percentage of body fat can have a negative effect on your overall well-being: Excess fat has been linked to numerous health problems such as increased risk for diseases such as cancer, diabetes and heart disease. Having excess fat, specifically surrounding the internal organs, can damage your health and contribute to serious medical conditions such as liver disease.

Assessing body mass index (BMI) is a commonly-used method of measuring body fat. While BMI does not measure body fat directly, it helps to assess health risks related to body mass. Ways to assess your body composition, and body fat percentage, more directly include measurement with calipers and tests such as underwater body fat test, the BodPod, DEXA Scan, and Bioletrical Impedence.

Weighing yourself on a regular bathroom scale does not truly assess your body composition, because a regular scale cannot tell the difference between how much of your total weight is comprised of water, fat, or muscle.

Learn More About Body Composition


Body Composition: NIDDK. National Institute of Diabetes and Digestive and Kidney Diseases. Dec 2007. http://www2.niddk.nih.gov/Research/ClinicalResearch/MCRU/MCRUBodyComposition.htm.

Roth, Walton, et al. Fit & Well: Concepts and Labs in Physical Fitness and Wellness 5th Ed. Boston: McGraw-Hill College, 2002.

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