This is made up of:
- Body fat: 40%
- Ease of use: 30%
- Weight accuracy: 20%
- Weight sensitivity: 10%
Our test is carried out at the University of Sydney's Exercise and Sport Science laboratory. Eight CHOICE volunteers (five males and three females) are weighed using underwater weighing (UWW), regarded as one of the best methods for determining a person's body fat. It measures the weight of water displaced when someone is submerged, and uses this value (together with dry weight, height and residual lung volume) to calculate body density, from which body fat percentage can be derived.
The person is weighed first on a normal calibrated scale, then again in a special underwater scale. Because bone and muscle are denser than water, someone with more bone and muscle mass will weigh more in water than on land and so will have a higher body density and lower percentage of body fat. Conversely, fat is less dense, so someone with more fat will be lighter in water.
In the same session, the volunteers are weighed on each of the scales. The average difference in percentage body fat between UWW and that measured by the scales is calculated and scored.