Define Techniques for Measuring Body Composition - Underwater weighing?

Underwater weighing (densitometry): It applies the Archimedean principle of water displacement by the fully submerged individual. The specific gravity is determined by dividing the body weight by the body volume. Tables have been developed that show the percentage of body fat for a given specific gravity. A body specific gravity of 1.048 is equivalent to 25 percent body fat; a specific gravity of 1.002 is equal to a fat content of 49.3 percent.