Which body composition measurement technique calculates body density?

Underwater weighing, also known as hydrostatic weighing, is a technique that calculates body density by assessing a person’s weight in air compared to their weight when submerged in water. This method relies on Archimedes' principle, which states that an object submerged in fluid experiences a buoyant force equal to the weight of the fluid displaced.

To determine body density, the person's weight is measured in both the air and the water. The change in weight, when submerged, allows for the calculation of the volume of water displaced, which is then used to derive body density. The density of the body can subsequently be used to estimate body fat percentage, as lean tissue is denser than fat tissue.

Other techniques mentioned, such as Bod Pod technology, skinfold measurements, and bioelectrical impedance analysis, utilize different mechanisms for estimating body composition but do not directly calculate body density in the manner that underwater weighing does. Bod Pod technology uses air displacement instead of water to assess body volume, skinfold measurements rely on calipers to estimate fat thickness at various sites, and bioelectrical impedance analysis measures resistance to electrical flow in the body, which correlates with fat and lean mass. Each of these methods has its unique methodology, making underwater weighing the specific technique