This is achieved through a permuted block design with block size of 12, 16, and 20 units width (W.F. Rosenberger, J. Lachin. Randomization in clinical trials: theory and practice. Wiley and sons, 2002, pag. 57). This method allows an almost complete uniform distribution of the randomisation groups in every moment of the study; this is necessary in order to simplify the subsequent courses management (see below). Participants are told about their group allocation at the time of biological sampling / anthropometric measurements, only.