How do you calculate lean body mass?
Lean body mass is body weight minus estimated fat mass.
Formula: body weight × (1 − body-fat percentage ÷ 100).
Example: at 80 kg and 20% body fat, estimated lean body mass is 80 × 0.80 = 64 kg.
The result is an estimate and depends on the accuracy of the body-fat input; it is not a medical diagnosis.
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