Calculation of lean mass

Your mass excluding fat: muscles, bones, organs, water. The right benchmark to target your protein intake.

What is lean mass?

Lean body mass (or LBM) includes your entire body without fat: muscles, bones, organs, water, skin. This is the metabolically "active" component: the higher your lean mass, the higher your basal metabolism.

The Boer formula

The Boer formula (1984) estimates lean mass from height and weight, with different coefficients by sex:

Men: LBM = (0.407 × weight kg) + (0.267 × height cm) − 19.2
Women: LBM = (0.252 × weight kg) + (0.473 × height cm) − 48.3

What is this calculation for?

Three main uses:

Target your proteins: 1.6–2.2 g/kg of lean mass depending on your objectives (maintenance, muscle gain, lean).
Track your progress: gaining muscle translates into an increasing LBM.
Calculate a more precise BMR: the Katch-McArdle formula uses the LBM (= BMR 370 + 21.6 × LBM) and is more precise for athletes with above average muscle mass.

Limits

The Boer formula assumes an "average" body composition. For a very muscular athlete or an obese person, the deviation from the DEXA measurement can reach ±5%. To be combined with other measurements (US Navy fat mass, impedancemetry) for validation.

À consulter aussi

Taux de masse grasse La part "graisse" Besoins en protéines g/kg de masse maigre BMR Métabolisme de base IMC Indice de masse corporelle

Questions fréquentes

Because protein needs are linked to your active muscle mass, not your fat. 2 g/kg of total weight greatly overestimates the needs of a person with excess fat.

Lean mass includes everything that is not fat: muscles, bones, organs, water, skin. Strict muscle mass is only a portion (around 40–50% of lean mass).

Regular bodybuilding (3 sessions/week minimum) + sufficient protein intake (1.6–2.2 g/kg LBM) + sleep and recovery. Muscle gain is slow: 1–2 kg of lean mass per year in a non-beginner adult.