Measuring and understanding body fat percentage correctly
Methods, reference values and practical tips
The body fat percentage indicates what percentage of body weight consists of fat mass. Unlike BMI, which only considers weight and height, body fat percentage distinguishes between fat mass and muscle mass. This makes it a more meaningful indicator of body composition and health risk. Our U.S. Navy method estimates body fat percentage from circumference measurements and requires only a simple tape measure.
The U.S. Navy formula is based on logarithmic calculations. For men, waist (at navel height), neck and height measurements are used. For women, hip circumference is also included, since women tend to store more fat in the hip and buttock region. The method was originally developed for fitness tests in the US military and has since been used worldwide because it is practical, inexpensive and reproducible. The average measurement error is ±3–5 percentage points compared with clinical methods.
A certain essential body fat percentage is vital for the body: it is needed for hormone production, protects internal organs and insulates the body. For men, this minimum is around 3–5%, for women around 10–13%. Falling below this value endangers health. Athletic body fat levels are 6–13% for men and 14–20% for women. An elevated body fat percentage above 25% (men) or 32% (women) is associated with an increased risk of cardiovascular disease, diabetes and metabolic syndrome.
For tracking progress over time, the tape measure method works well: always measure at the same time of day (ideally in the morning before breakfast), always at the same spots and with the same tape measure. Weight fluctuations from water or bowel contents affect this method much less than body fat scales (BIA). For absolute precision, clinical DEXA measurement remains the gold standard – useful before and after targeted body composition programs.