Which method of body composition assessment utilizes underwater weighing?

Hydrostatic weighing, also known as underwater weighing, is a method of assessing body composition that involves measuring a person's weight in water and air. This technique is based on the principle of buoyancy, where the displacement of water correlates with body density. By determining body density through this method, it can be inferred how much body fat and lean body mass a person has.

This approach is highly regarded for its accuracy because it accounts for the density of both fat and lean tissue. Fat is less dense than water, while lean tissue has a higher density, so the differences in buoyancy provide valuable data for calculating body fat percentage.

In contrast, the other methods listed, such as bioelectrical impedance analysis, dual-energy X-ray absorptiometry, and skinfold measurements, rely on different principles and technologies that do not utilize the water displacement method characteristic of hydrostatic weighing.