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FFMI-Rechner

Miss deinen Fat-Free-Mass-Index und vergleiche mit der natürlichen genetischen Grenze (Kouri et al., 1995). Inklusive Größen-Normalisierung.

What Is FFMI and How Does the Kouri Formula Work?

The Fat-Free Mass Index (FFMI) is a body composition metric that normalizes lean body mass to height, similar to how BMI normalizes weight to height. It was popularized by a 1995 study led by Harrison Pope and Richard Kouri, which examined the muscularity of drug-free bodybuilders and found that FFMI rarely exceeded 25 in natural athletes. The basic formula is lean body mass in kilograms divided by height in metres squared. The normalized version adds a correction factor of 6.1 multiplied by 1.8 minus height in metres, which adjusts for the fact that taller individuals naturally carry more lean mass. To calculate FFMI you first need your body fat percentage, then lean mass equals weight multiplied by one minus body fat fraction. FFMI is more informative than BMI for anyone who trains seriously, since it strips out the effect of body fat and focuses purely on muscular development.

Interpreting Your FFMI Score

Typical FFMI ranges for men fall between 18 and 20 for untrained individuals, 20 to 22 for recreational lifters, 22 to 23 for experienced natural athletes, and 24 to 25 for advanced drug-free competitors. An FFMI above 25 in men is strongly associated with anabolic steroid use according to Kouri's original research, though a small number of genetically gifted individuals reach this level naturally. For women, ranges are lower due to hormonal differences, typically 15 to 17 for beginners and 19 to 21 for elite natural athletes. Use FFMI to track long-term progress rather than day-to-day changes. Because the metric depends on body fat percentage, measurement error in body fat translates directly into FFMI error, so consistent measurement methods matter more than absolute precision.

Häufig gestellte Fragen

What is a good FFMI?▼
For men, an FFMI of 20 to 22 indicates a recreational lifter, 22 to 23 an experienced natural athlete, and 24 to 25 an advanced drug-free competitor. For women, 16 to 18 suggests consistent training and 19 to 21 is achievable for elite natural athletes. The exact interpretation depends on height, body fat percentage, and training history.
Is an FFMI above 25 possible naturally?▼
The 1995 Kouri study concluded that an FFMI above 25 is extremely rare in drug-free athletes and strongly correlates with anabolic steroid use. However, a small percentage of individuals with exceptional genetics, including unusually favorable androgen receptor density or myostatin mutations, may reach or slightly exceed 25 naturally over many years of elite training.
What is the difference between FFMI and BMI?▼
BMI is weight divided by height squared and does not distinguish muscle from fat. FFMI replaces weight with lean body mass, so it isolates muscular development. An athlete with a BMI of 27 might have an FFMI of 23, indicating high muscle mass rather than excess fat. FFMI is therefore far more useful for lifters and strength athletes.
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