What is Lean Body Mass?
Lean Body Mass (LBM) represents the weight of your body minus all fat mass. It includes your skin, bones, ligaments, tendons, organs, and water content. It is essentially everything in your body that is not fat.
Knowing your LBM is often more useful than just knowing your weight because it allows you to calculate your BMR (Basal Metabolic Rate) more accurately and track whether weight gain is due to muscle or fat.
Why Use Formulas?
While DEXA scans and hydrostatic weighing are the gold standards for accuracy, they are expensive and inaccessible for most people. Mathematical formulas derived from population studies provide a reasonably good estimate for the general population.
The Formulas Used
- Boer Formula (1984): Generally considered the most accurate for non-obese individuals. It is the default recommendation in this calculator.
- Hume Formula (1966): Another widely respected formula, often returning results very similar to Boer.
- James Formula (1976): A simpler formula but known to underestimate LBM in individuals with higher body fat percentages.