حاسبة الكتلة العضلية

What Are Lean Body Mass and FFMI?

Lean body mass (LBM) is everything in your body that is not fat: muscles, bones, organs, water, and connective tissue. Knowing your LBM helps you understand how much of your weight is functional tissue versus stored energy. The Fat-Free Mass Index (FFMI) takes lean body mass a step further by normalising it to your height, similar to how BMI normalises total weight. FFMI is calculated as lean mass in kilograms divided by height in metres squared. An FFMI of 18 to 20 is average for men, 20 to 22 indicates above-average muscularity, and values above 25 are extremely rare without performance-enhancing substances. For women, typical values are lower by about 3 to 5 points.

What FFMI Can You Achieve Naturally?

Research into natural bodybuilders and athletes suggests that an FFMI of around 25 represents the upper limit for most drug-free men, with exceptional genetics occasionally reaching 26 to 27. For women, the natural ceiling is generally around 21 to 22. These numbers are useful benchmarks for setting realistic physique goals. If someone claims a natural FFMI well above 25, it may warrant scepticism. FFMI is also a valuable tool for tracking progress during a bulk or cut: if your FFMI increases during a surplus, you are likely gaining muscle, and if it holds steady during a deficit, you are successfully preserving lean mass while losing fat.

Frequently Asked Questions