[Body composition analysis in obesity: radionuclide and non radionuclide methods]

Body composition (BC) assessment provides important information regarding the absolute or relative amount of bone, lean and fat tissue. Different somatometric techniques have been applied in numerous epidemiological and experimental studies, as well as in every day clinical practice. Traditional techniques for BC analysis include skin fold thickness measurements, radioisotope dilution methods, hydrodensitometry and underwater weighing, while newer techniques include bioelectrical impedance analysis (BIA), air displacement plethysmography (ADP), dual energy X-rays absorptiometry (DEXA), computer tomography and magnetic resonance imaging. In addition, positron emission tomography helped to the functional investigation of adipose tissue, in particular of brown tissue. All these techniques have contributed a lot to the understanding of physiological conditions such as exercise training, menopause and ageing, adolescence health parameters, as well as pathological conditions such as disorders of nutrition, cancer, obesity and diabetes mellitus. In obesity, BC contributed to diagnosis and the pathological impact of visceral adipose tissue. In addition, conditions such as pseudo- or hypermuscular obesity and sarcopenia, which are often observed in various endocrine diseases, were investigated in detail by using such methods. During weight loss, some of these methods were quite accurate in measuring changes in fat and lean mass. Apart from anthropometric measurements, a BC measurement if possible should be included in obesity assessment. Measurements of skin fold thickness combined with BIA are quite sufficient for routine clinical practice. However, in specialized clinics and in research, more sophisticated methods like ADP or DEXA are used.