Body composition assessment is used to identify health risk that comes with having high or low levels of body fat. During the assessment, the BMI is calculated using body weight and height. However, a false high value is possible for highly muscular individual. The waist circumference is measured with a tape measure around the smallest part of the waist. It is one of the best ways to predict risk for diseases relating to obesity such as cardiovascular diseases. Larger the circumference means higher the risk. Lastly, the SO5S is done using a caliper to pinch and measure the thickness of fat under the skin on 5 sites: triceps, biceps, subscapular (upper back), iliac crest (love handles), and medial calf.
Individually, each of the 3 tests is not perfect for assessing health related to fatness. The BMI does not distinguish between fat or lean mass. Both the BMI and the SO5S do not account for fat around the organs, which are dangerous to health at high volume. The waist circumference does not account total body fat distribution. However, the combination of all 3 tests together will provide a better assessment of health risk related to body composition and fat distribution.