Moisture is the fundamental requirement for the skin barrier to function. A lack of sufficient moisture contributes to a decline in the skin barrier’s function which causes sensitivities and many other unfavourable conditions. Lack of moisture under the skin also causes the skin to thicken as the outermost layer (horny layer) reacts to protect the skin as the result of drying out, just like the soles of the feet get dry during the winter. In contrast, too much moisture can be a concern too, much like being overweight has become more of an issue than malnutrition in the developed world.