Body Composition. How to Measure It?
A reference body composition measuring method, does it exist? No. Various methods have their pros and cons. That is why a physician can recommend the most suitable option for every patient.
What Does Body Composition Data Tell Us?
Body composition provides important information about health. Measurements of various body composition elements – bones, muscles, fat tissues, water, and others – allow to evaluate:

• ·    Inner fat level and risks the inner fat presents to your health provoking diabetes, heart diseases, low testosterone level etc.;
• ·    How and by which means to lose weight;
• ·    How your workout program does influence the growth and toning of muscles;
• ·    What is the condition of your bones and risks of osteoporosis development;
• ·    Is there a muscle disbalance and what are trauma risks;
• ·    Water balance in body, since water deficit or excess impedes normal functioning of the body (oxygen supply to tissues diminishes, the heart and kidneys are excessively stressed, body performance capability reduces).

A reference body composition measuring method, does it exist?
No. Various methods have their pros and cons. That is why a physician can recommend the most suitable option for every patient.

Main body composition measuring methods

Neutron Activation Analysis (NAA)
Patient is submitted to a radioactive emission. Special counters record radioactive isotopes emitted by the body. Obtained measurements provide body composition diagnostic data (up to 40 elements).

Method’s advantages:

• ·    A comprehensive and precise diagnostic data is obtained.

Method’s disadvantages:

• ·    The patient is exposed to a radiation source;
• ·    Irregularity of readings.

Natural Radioactivity of the Human Body
The source of natural radioactivity of the human body is potassium nuclide. Its measurements are used for studying the diseases related to endocrine disorders and liquids disbalance in the body.

Method’s advantages:

• ·    Low error level 1-5 %;
• ·    Duration 15 – 30 minutes;
• ·    Safe method.

Method’s disadvantages:

• ·    Analysis of specific sectors only.

Dilution Methods
Isotopes are injected into the body intravenously. Their dilution provides data about water level in the body.

Method’s advantages:

• ·    High accuracy.

Method’s disadvantages:

• ·    Long duration (up to several days and nights);
• ·    Intravenous injection + blood analysis needed;
• ·    The patient is exposed to a radioactive emission.

Hydrostatic Densitometry
An upgraded Archimedes method. A body is dipped into water, but the volume of the water discharged equals to the body volume. The volume data is further compared to the person’s weight, and fat percentage is calculated.

Method’s advantages:

• ·    Shows the real fat tissue volume in the body and is considered a reference method of fat tissue measuring.

Method’s disadvantages:

• ·    Long duration – 45 minutes – 1 hour;
• ·    Specific methodology (being under water for a quite prolonged time may be embarrassing for children, seniors and persons suffering from various diseases);
• ·    Substantial errors possible due to different bone density depending on race, gender, age. Deviations possible when measuring pulmonary residual volume.

Air Displacement Plethysmography (ADP)

Similar to the hydrostatic weighting method since based on the same principles. Here, the volume of the displaced air is being measured.

Method’s advantages:

• ·    Possible error of repeated measurements is under 0.3 %.
• ·    The whole measuring procedure takes up to 5-7 minutes only.

Method’s disadvantages:

• ·    Expensive equipment.
• ·    May become complicated for persons suffering from claustrophobia.

Dual-Energy X-ray Absorptiometry (DEXA)

A roentgenologic method of body composition analysis intended to measure bone mineral density, evaluate quantity of fat and non-fat tissues in the body, including segmental measurements.

Method’s advantages:

• ·    Duration 2-3 minutes.
• ·    Highly informative, accurate, safe method.

Method’s disadvantages:

• ·    Exposure to x-rays source (recommended once per year only).
• ·    Expensive equipment.
• ·    Use in stationary conditions only.

Computed Tomography (CT)
Parts of the body are being scanned by X-rays at various angles. Special detectors register the outcoming X-ray flow. Computer generated analysis allows to evaluate precisely the quantity of subcutaneous and inner fat, mass of skeletal muscles and internal organs.

Method’s advantages:

• ·    A sample body composition measuring method as per tissue types.

Method’s disadvantages:

• ·    The patient is exposed to a radiation source;
• ·    Expensive equipment.
• ·    Use in stationary conditions only.

Magnetic Resonance Imaging (MRI)
The method is based on measuring electromagnetic response of atom nucleus (normally hydrogen atoms nucleus) by exposing them to a certain combination of electromagnetic waves in a constant high-frequency magnetic field.

Method’s advantages:

• ·    Chemical body composition data can be obtained.
• ·    Provides data on fat and non-fat tissue distribution in the body.
• ·    Muscle tissue condition.
• ·    Safe method without exposure to ionizing radiation.

Method’s disadvantages:

• ·    Expensive method.
• ·    Long examination duration.
• ·    Use in stationary conditions only.

Anthropometry
Measurement of human proportions and proportions of the human body parts. Includes weighting, measurements of the person’s height, chest, hip circumference, skinfolds of certain body parts. Those measurements give a clue to various indexes, and mainly body mass index.

Method’s advantages:

• ·    Safe and simple method.

Method’s disadvantages:

• ·    Low accuracy.
• ·    The interpretation of the results may depend on many factors (man/woman/athlete/race).

Bioelectrical Impedance Analysis (BIA)
The electrical conductivity of the body tissues varies due to different content of liquids and electrolytes. A weak electrical signal is being transmitted over the human body in order to measure electrical impedance. The obtained measurements provide quantitative characteristics of different body components.

Method’s advantages:

• ·    Quick, accurate, simple method.
• ·    Low cost.
• ·    Mobile device.
• ·    Acceptable accuracy and low margin of error.
• ·    Comfort.

Method’s disadvantages:

• ·    The method is based on liquid content in the body, so in case of body dehydration the results can be inaccurate.
• ·    Erroneously high measurements of fat level for athletes, bodybuilders.

The Bioelectrical Impedance Analysis (BIA) is the most future-oriented and popular body composition measurement method. Fat mass measurements obtained through the BIA method are comparable to DEXA method measurements, but the results of segmental measurements correspond to those obtained by the computed tomography. At the same time measurement devices are portable, totally safe, and user-friendly. Moreover, continuous software development contributes to accuracy, informativity, and visibility of results.