Lean body mass is a component of body composition, calculated by subtracting body fat weight from total body weight: total body weight is lean plus fat. In equations:
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LBM = BW − BF LBM + BF = BWThe percentage of total body mass that is lean is usually not quoted – it would typically be 60–90%. Instead, the body fat percentage, which is the complement, is computed, and is typically 10–40%. The lean body mass (LBM) has been described as an index superior to total body weight for prescribing proper levels of medications and for assessing metabolic disorders, as body fat is less relevant for metabolism.
Estimation
LBM is usually estimated using mathematical formulas.
The following formula may be used:
For men: LBM = (0.32810 × W) + (0.33929 × H) − 29.5336
For women: LBM = (0.29569 × W) + (0.41813 × H) − 43.2933
where W is body weight in kilograms and H is body height in centimeters.
A nomogram based on height, weight and arm circumference may be used.
Actual measurement
Instead of mathematical estimation the actual value of LBM may be calculated using various technologies such as Dual-energy X-ray absorptiometry (DEXA).