Bioelectrical impedance analysis is not approved in extreme body mass index and body fluid ranges. These conditions however may present in chronic heart failure patients. Thus it is essential to validate BIA to the gold standard DXA method which is our primary aim. Patients admitted to Gottsegen György Hungarian Institute of Cardiology with acute decompensation of chronic heart failure will be enrolled in this prospective study. Enrolled participants will undergo body composition measurements with dual-energy X-ray absorptiometry (Hologic, Delphi QDR) and bioelectrical impedance analysis (Bodystat, Quadscan 4000) methods. The main measured parameters - body weight, total body water, fat mass, fat-free mass (lean weight), extracellular mass, body cell mass, resistance, reactance, phase angle, basal metabolic rate - will be registered in database. Statistical analysis of data acquired by the different methods will be performed to validate BIA.