You may have heard the story of Archimedes who was tasked with detecting whether or not the king’s golden crown had been mixed with silver. After 
much thought he realized that he could calculate the density of pure gold from the weight of the crown and the weight of the water that it displaced. Legend has it that this occurred to him at a public pool in Sicily more than 2,000 years ago and he leapt from the pool and ran down the street naked shouting “Eureka” which is Greek for “I found it!”
Hydrostatic Weighing: What is it and what is the purpose of it?
The density of the human body can also be calculated by Archimedes’ principle using a person’s dry weight and the weight of water which is displaced when the body is immersed in water. The procedure for weighing someone underwater is called “hydrostatic weighing”. Why would one want to know their body density? Because body density is the most accurate way to estimate body fat and its complement, lean body mass. Until recently hydrostatic weighing was rarely performed outside of university research laboratories because of the high cost of equipment and the complexities of the procedure. But that has all changed completely through technological innovations such as computerized electronic weighing and the invention of the Floataweigh, a weighing system that floats in the water. Now underwater weighing can be done by anyone with access to a pool. The Floataweigh measures the weight of the immersed body and transmits it to a computer by means of radio waves. EXERTECH’s user-friendly computer software instantly calculates body fat percent and lean body mass in real time. The software even allows hydrostatic weighing to be done without head submersion by incorporating the latest research for estimating head volume from girths using a tape measure. Forget about “body mass index” (BMI) which classifies muscular individuals as “obese”! Get a Floataweigh and you will have the “gold standard” in body composition assessment with light weight, portable equipment and state-of-the-art software.