The phenomenon of a pressure profiles self-consistency in tokamak plasmas is interpreted in the framework of a 'thermodynamic' approach, used successfully in complex non-equilibrium systems studies. The solutions for the self-consistent pressure profiles are in accordance with experimental pressure profiles. The heat transport features in the vicinity of the minimum of the free energy are analysed. The deduced energy confinement scaling law is in qualitative agreement with the empirical so-called IPB98(y,2) scaling law.