Body Composition

Body Fat Percentage

Percentage of body fat can be measured in a number of ways. Most make use of the different densities of body fat versus lean tissue.

Hydrostatic Weighing

Hydrostatic weighing has long been considered the gold standard. In this process, the body is weighed in air, and then in water. The difference is then used to calculate what percentage of the weight is lean tissue, and what is fat. The highly specialized equipment, coupled with the tendency to not be viable for people afraid of being submerged in water, does make it a less practical option, though.

Bio-electrical Impedance and Near Infrared Light

These two options also use the different densities as the basis for their measurements. They are also very convenient, as the measurement is very quick, and simple, provided you have the equipment. However, both have been shown to be inconsistent, as well as less accurate. Therefore, they are not widely suggested methods.

Skinfolds

This is possibly the most practical method of testing body fat, due to the ease of administration, as well as proven close approximation to measurements done by hydrostatic weighing. This method uses calipers to measure the amount of sub-cutaneous fat at a combination of selected sites around the body. These measurements can either be inputted in calculations devised for this test, or compared to norms. The norms are typically a table of measurements which have already been calculated using the equations. When performing the skinfold measurement, the fold is always made in the direction of the muscles below the skin. In other words, where the muscle runs diagonally, the skinfold should follow the same diagonal line. The same applies for vertical muscles and horizontal options too. Though, the use of horizontal folds is exceptionally rare.

Commonly used combinations of sites include:

3-Site:

• Best used for large testing groups

Males – Chest, abdomen and Thigh
Females –Triceps, Supra-Iliac, Thigh

4-Site:

• Used in situations where lower body sites are not accessible due to clothing

Bicep, Triceps, Subscapula, Supra-Iliac

6-site:

• Best used for individuals

Bicep, Triceps, Subscapular, Supra-Iliac, Thigh, Calf

Understandably, the accuracy of the overall measurement will increase with increased number of sites used. But, it is often more practical to use fewer sites. This may be due to time restrictions, or purely ease of access to the sites. When choosing which combination of sites to use, these factors must always be considered.

Skinfold Measurement Sites

1. Chest (Males only)