Methods for Body Composition Analysis in Adults

Fat and lean components of the body including total body fat, fat-free mass and total body water and ectopic fat accumulation are important constituents that link obesity, aging, and chronic disease to subsequent morbidity and mortality. The methodology of body composition is based on a series of models characterized by progressive levels of anatomical complexity. A commonly used example is five-level model: atomic, molecular, cellular, tissue-system, whole body. Each body composition analysis method targets a component or a subcomponent of the five-level model of body composition. The choice of body composition analysis method greatly depends on the question being asked, the setting where the measurement is performed and the availability of measuring devices. Body composition analysis methods vary in complexity and precision, and range from simple field based methods to more technically challenging, laboratory based methods. Although several methods have been developed to assess body composition, anthropometric indices are simple, safe and cheap measures to quantify obesity. Body mass index, calculated from height and weight, is the most frequently used, quickest and the easiest measure. As body mass index does not differentiate peripheral from abdominal obesity, the use of waist circumference and waist-to-hip ratio was proposed in various guidelines. Waist-to-height ratio is emerging as a new anthropometric index with a potential for global use in different ethnic groups and in adults and children. The minimum measurements to be made in the basal evaluation of overweight patients are weight, height and waist circumference to calculate body mass index and waist-to-height ratio.