A method for determining the hydration, fitness and/or nutrition status of a human body, or of segments of the human body, comprises providing values each of a mass or volume fraction of intracellular water and a mass or volume fraction of extracellular water of the human body or the segment, defining a two-dimensional parameter space, determining a reference line within the parameter space, locating a position within the parameter space which corresponds to the associated values of the mass or volume fraction of intracellular water and the mass or volume fraction of extracellular water of the human body or the segment, determining a distance between the position and the reference line, and deriving a mass or volume, or a mass or volume fraction, of hydration from the determined distance from the reference line for the human body or the segment.
