The fat mass (or FM, from the English Fat Mass) represents the totality of lipids present in the human body. Usually expressed as a percentage of the total body mass, it is made up of two components: the primary fat and the storage fat.
By essential fat, or primary fat, we mean the amount of fat contained in the central nervous system, bone marrow, mammary glands, kidneys, spleen and other tissues. Given this particular anatomical location, essential fat has a physiological role of primary importance, to the point of being considered:
the minimum percentage of fat mass compatible with a state of good health.
For males, this value should not fall below 3-5% (already at these levels there is a greater susceptibility to infections), while in females the primary fat should be above 12% (already at levels below 16 percentage points some athletes become amenorrhoeic, with significant loss of bone minerals).
The storage fat, accumulated in the adipose tissue, represents the main energy reserve of the organism; it is found above all at the subcutaneous level, but also in the visceral area (the proportion between the two varies according to age, sex, ethnicity and state of form Physics) Normal values are around 12%.
For what has been said so far, if mathematics is not an "opinion," in the reference man and woman the fat mass represents, respectively, 15 and 24% of the total body mass. These values are much lower in athletes, where levels close to the primary fat percentage are reached, and much higher in the obese.
The determination of the fat mass in vivo can take place according to different methodologies, which differ in practicality, accuracy and costs (plicometry, bioimpedance analysis, body circumferences, Dexa, creatinine, magnetic resonance, CT, K40 and ultrasound). An even simpler and more immediate method is to calculate the lean mass starting from the height and some body circumferences, according to the formula developed by Wilmore and Behnke:
Men FM (%): 495 / {1.0324 - 0.19077 [log (waist-neck)] + 0.15456 [log (stature)] - 450
Women FM (%): 495 / {1.29579 - 0.35004 [log (waist + hips-neck)] + 0.22100 [log (stature)]} - 450
By comparing the result obtained with the values in the table, you can have an "idea of your level of fitness.
