Estimate lean body mass using the Boer formula.
Men: LBM = 0.407w + 0.267h - 19.2
Women: LBM = 0.252w + 0.473h - 48.3
For general wellness information only — not medical advice. Consult a healthcare professional for personal guidance.
Lean body mass (LBM) is your total body weight minus fat mass — muscle, bone, organs, water and connective tissue combined — and it's a more useful number than body weight alone for tracking real progress during a diet or training programme, because a scale can't tell you whether weight lost was fat or muscle. Formula-based LBM estimates (like the Boer formula, using height, weight and sex) are a practical substitute for a DEXA scan or bioelectrical impedance measurement, which most people don't have regular access to, but they're still estimates built from population averages, not a direct measurement of your specific body composition.
LBM matters directly for nutrition planning: protein needs are best set relative to lean mass, not total body weight, since it's the metabolically active tissue that actually uses dietary protein for repair and growth — using total weight instead can meaningfully overestimate protein needs for someone carrying a higher body fat percentage. Tracking LBM over a diet also gives an early warning sign: if the scale is dropping but LBM is dropping nearly as fast as total weight, that usually signals too aggressive a calorie deficit or too little protein and resistance training, and it's worth adjusting before more muscle is lost.
Everything in your body that isn't fat — muscle, bone, organs, connective tissue and body water. It's calculated as total body weight minus estimated fat mass, and is generally a more useful figure than total weight for tracking whether a diet or training programme is preserving muscle.
Formula estimates (built from height, weight and sex, such as the Boer formula) are a reasonable practical substitute when you don't have access to a DEXA scan or bioelectrical impedance device, but they're derived from population averages and won't match a direct body-composition measurement exactly for any individual.
Protein is used by metabolically active tissue — mainly muscle — for repair and growth, and lean mass is a better proxy for that than total body weight. Using total weight instead can overestimate protein needs, especially for someone with a higher body fat percentage, since fat tissue doesn't use dietary protein the same way.
The scale can't distinguish fat loss from muscle loss. If LBM is falling nearly as fast as total body weight during a diet, that's usually a sign the calorie deficit is too aggressive or protein/resistance training is insufficient — catching that early lets you adjust before losing more muscle than necessary.