<unk> , also referred to as "underwater<unk> ",<unk>  body composition analysis", and "hydrodensitometry" is a technique for measuring the density of a living person's body. It is a direct application of Archimedes' principle, that an object displaces its own volume of water.
Hydrostatic weighing
Helium dilution technique
Evaporimetry
AutoAnalyzer
High-performance liquid chromatography
Whole-body counting
Nephelometry 
Thermoluminescent dosimeter