By healthiergang writer , student in Pharmacy.
Fat Mass and Lean Mass
For Fat Mass (or FM, Fatty Mass, in English) we mean the mass part of our body made up of adipose tissue. All the remaining component (organs, bones, liquids, etc. ..) makes up the Lean Body Mass (or LBM, Lean Body Mass, in English).
In reality, there is a type of fat that is also included in the count of lean mass: it is the essential fat, essential for our body to perform various physiological functions, and normally not involved in slimming processes. This constitutes, in men, 3% of the body mass, while 12% in women.
If we also exclude this part of fat from the lean mass, we will speak of alipidic lean mass (or FFM, from the English Fat-Free Mass).
Differences
Let's see from a composition point of view in what mainly fat mass and lean mass differ.
Fat Mass: it is composed of the various types of adipose tissue: white (visceral, subcutaneous, peripheral), brown, and intramuscular triglycerides.
Lean Mass: the main component is water, which can be present for weight values ​​from 40% to 70%, depending on the subject. This is followed by protein mass, stored glycogen, essential fat and various minerals.
How to calculate fat mass?
Thanks to special equations we are able to calculate, or rather estimate, our body fat percentage; just have paper, pen and a measuring tape (or use one of the many calculators available online). An example is the Wilmore and Behnke formula:
- for humans: FM (%): 495 / {1.0324 - 0.19077 [log (waist-neck)] + 0.15456 [log (stature)] - 450
- for women: FM (%): 495 / {1.29579 - 0.35004 [log (waist + hips-neck)] + 0.22100 [log (stature)]} - 450
Obviously the value we will obtain will be indicative but, although usually not true, it can be of some use.
If, on the other hand, we want to really measure body fat, today we can use various techniques, different from each other above all in terms of practicality and precision.
Plicometry
The most common technique is undoubtedly plicometry, a relatively simple, practical and effective method. This involves the use of an instrument, similar to a caliber, called a skinfolder: with the index and thumb you go to lift and firmly grip a fold of skin, which will then be measured through the skinfolder; it is good to move the fold beforehand in order to detach the underlying muscle tissue. The most commonly measured folds are the suprailiac, bicipital and pectoral folds.
To obtain a measurement that is as realistic as possible, it is good to take at least 2 measurements, and obtain the average (letting the skin rest for a few minutes between one measurement and the other). If the measurements of the same fold are too different (more than 10%) it is a good idea to perform a third one.
The data obtained are then compared and inserted in appropriate equations and graphs, to obtain a measurement of body fat (eg the Nomogram by Jackson et al.).
However, to perform a truly effective skin test, technique and experience are required, as well as adequate instrumentation. However, in practice, even an "improvised" measurement can be in a certain sense effective, not so much in the actual determination of body fat, but rather in monitoring any progress, comparing our measurements over time.
In addition, plicometry allows, by measuring skin folds of different parts of the body, to obtain a realistic picture of the distribution of body fat.
Limits of Plicometry
However, plicometry has an undeniable number of limitations:
- there is a certain margin of human error;
- it does not allow truly reliable measurements in severely obese or elderly subjects;
- does not allow to measure visceral fat;
- the measurement of fat mass by plicometry is strongly influenced by the hydration of the subject.
The second technique most commonly used in the determination of fat mass is Bioimpedancemetry, which is more precise and effective than plicometry.
Bio-impedancemetry
Bio-impedancemetry (BIA) is a rapid, precise and non-invasive technique for determining body composition (lean mass, fat mass and liquids), through the use of a specific device, more or less complex. In general, the subject is connected to the machine by means of electrodes, applied on the back of the hands and feet.
Once started, the bioimpedance meter measures the impedance of the body (in electronics, impedance is defined as the force of opposition of a circuit to the passage of a current), and then collects the resulting data.
Therefore bioimpedance analysis leads to the determination of the body composition (CC) by exploiting the different conduction properties of the various tissues; for example, fat will have a lower impedance than lean tissue, which is richer in water and electrolytes.
Bioimpedance measurement is also not free from measurement errors; these can be caused both by human error and by an error of the machinery itself; moreover, different machines can give different values ​​in turn. The operator must also take into consideration all the parameters that could alter the final measurement, such as the subject's hydration status, his body temperature, and any fasting and / or physical activity carried out during the hours preceding the measurement.
While plicometry allows you to directly obtain only the measurement of body fat, thanks to bioimpedance we can detect:
- the fat mass;
- lean mass;
- the cell mass;
- muscle mass;
- total body water;
- intracellular water;
- extracellular water.
Other commonly used techniques
DEXA: is the method considered to be the most precise and effective; however it requires both a particularly expensive instrumentation and a certain collaboration on the part of the subject, who must remain practically motionless for about 10-20 minutes.
BOD POD Plethysmography: the patient enters a booth, and remains there for about 5 minutes, until the machinery connected to it has processed and transmitted the data obtained.
TOBEC: uses a plant capable of generating a magnetic field and observing the different electrical conductivity of the tissues; although very accurate, it is little used due to the high costs.
Conclusion
To date, thanks to the different techniques available, we are able to measure and evaluate our body composition and therefore obtain important information not only about our sports performance, but also about our state of health.
In fact, evaluating body composition means measuring the various components of our body: we can monitor our progress, accurately quantify our improvements in terms of hypertrophy and definition, but also identify any health risks, and prevent certain pathological conditions.
Our articles should be used for informational and educational purposes only and are not intended to be taken as medical advice. If you are concerned, consult a health professional before taking dietary supplements or making major changes to your diet.
