Underwater Weighing Technique
The gold standard measurement for body composition assessment is known as “underwater weighing”. A person is weighed in air and under water and the difference in weight is used to assess the levels of body fatness. It is based on the fact that muscle is more dense than fat (muscle is like a rock and causes you to sink while fat is like styrofoam and helps you float. Therefore, the relative amount of fat can be determined by bouyancy or weight under water.