What Does Body Composition Mean? | Fitness, Health and Exercise Glossary
Posted Jan 07 2009 4:38pm
What Is Body Composition and How Is It Measured?
Definition of Body Composition
In physical fitness, body composition is defined as the percentage of fat, muscle, and bone in the body. Usually it’s expressed as a ratio of lean mass to fatty mass. Lean mass includes muscle, bone, skin, internal organs and body water. Fatty mass is mostly composed of body fat (subcutaneous fat) as well as internal essential fat surrounding organs. Body composition will typically be displayed as either a percentage of fat (body fat percentage or %fat) or as a percentage of lean body mass (LBM).
Why Is Body Composition Important?
Body composition is a much more accurate representation of a person’s leanness than scale weight or Body Mass Index (BMI), because it does not rely on height and weight alone to measure leanness. It measures the ratio of body fat to lean tissue and bone in the body, not scale weight.
This is important, because a person may have a high-scale weight (even for their height), yet have also have a high muscle-to-fat ratio which makes them extremely lean. That same person might be labeled overweight using the standard BMI calculation, which does not take into account body composition, only mass (weight) relative to your height, weight, age and gender.
Excess body fat, or a body composition with a high fat-to-muscle ratio is unfavorable because it increases the risk of cardiovascular disease, Type II diabetes, Metabolic Syndrome and certain cancers. Excess body fat, especially at levels considered obese, can also put stress on the joints and interfere with mobility and the ability to perform everyday activities.