The body is a complex organism that is made up of millions of cells, all working in progressively intricate systems of tissues and organs. Every cell in the body has a purpose, and to fulfil that purpose optimally they must be present in certain ranges. For example, humans have two eyes, innervated by millions of neurons. While one eye will work well enough, two gives a more complete visual range.
Body composition is made up mainly of the major tissues that give the body mass and weight: bone, fat, muscle and water, even though water volume is not added to the normal metrics of body composition measurement because of how variable it can be. The variance in these elements of body composition is what determines how big, or how lean a person will be. It is the ratio between total fat mass and lean muscle, putting into account the organs and tissues in interstitial places. It is one way of estimating the truest weight of a person, and know their true fat density, with applications in both medical and non-medical circles.
NORMAL RANGES OF BODY COMPOSITION
Bone mass makes up 2.5-5% of normal body composition, with women ranking on the lower end of the range, while men tend to rank on the higher end of the range.
Total body water measure not just “water”, but blood and interstitial fluids in both the cells and around them. It is a total of all the water in the body. Water makes up 45 to 65% of body composition, with 10% of fatty tissue and 75% muscle mass made up of water.
Body fat varies according to age, genetics and gender. Women generally have more body fat than men do, with the values ranging from 22-36% in women, starting at the lower range and moving up to the higher range as the women go through menopause. For men, the range is between 8-25%, increasing, as they get older.
Muscle mass measures striated, smooth and skeletal muscle weight, with normal ranges for women ranging between 63-72.5% and 75-84% for men.
TESTING FOR BODY COMPOSITION
There are many methods for estimating body composition, and while some are quick, they are seldom reliable. The different methods mean that there will be varying values that have different margins of error. However, some methods were approve, with slim margins of error that mean that the values can be reliable.
Bioelectric impedance is a method for measuring body fat. This method does not actually determine fat composition in itself, instead it measures the impedance caused by the interstitial spaces filled with fat when an electric current is applied. It can be used to measure total water, fat-free body mass and total fat of the body.
When current is applied to tissue, the cells provide a varying resistance, which can be measured as impedance. The electrodes are distributed evenly between the wrist and the ankle on the other side of the body from the chosen wrist, getting a measurement that covers the entire body.
Some factors can alter the true value of BIA, and these include:
Dual Energy X-ray Absorbtiometry is a method that uses x-rays to measure the density of the bones, alongside the body’s composition. X-ray beams of different intensities are passed across each body part individually, measuring bone, fat and even muscle.
This method’s accuracy is very high, and it is even more desirable because it measures the body composition in individual body parts, and so one can get to know what their limbs individually weigh. It might be expensive, but the accuracy makes it worth it.
Done while completely submerged, hydrostatic weighing compares body weight while completely dry to the body’s weight when submerged underwater in a bath. The two figures are calculated (considering the water’s density), giving an almost accurate number that represents the body’s composition.
Underwater scales are rare, but this method provides a more accurate reading with a very low percentage margin of error. For a more accurate reading, the subject will need to inhale and stay completely still. This method is most often used for research purposes.
AIR DISPLACEMENT PLETHYSMOGRAPH
Working with the same principle as hydrostatic weighing, the subject sits in an air vacuum chamber and is weighed, and the air displacement there is compared to his weight outside the chamber (putting into consideration the mass of the air in the vacuum).It’s non-invasive, fast, doesn’t require sedation or radiation exposure.
MAINTAINING NORMAL BODY COMPOSITION
Exercise: Aerobic exercises and resistance training build endurance and help to tone muscle, and with a mixture of a great diet, it can help to pack on the pounds. After the age of 30, muscle mass starts to deplete by almost 10% every decade. This means that to maintain muscle mass, a good exercise regime is needed.
Diet: A protein rich diet builds muscle mass and keeps a healthy fat composition. A diet rich in proteins, healthy vegetables, fruits and lean meat is ideal for keeping a healthy weight.
USES OF BODY COMPOSITION FIGURES