There is no consensus among reflexologists on how reflexology is supposed to work; a unifying theme is the idea that areas on the foot correspond to areas of the body and that by manipulating these one can improve health through one's
qi. Reflexologists divide the body into ten equal vertical zones, five on the right and five on the left. Reflexologists posit that the blockage of an energy field, invisible
life force, or
Qi, can prevent healing. Another tenet of reflexology is the belief that practitioners can relieve stress and pain in other parts of the body through the manipulation of the feet. One claimed explanation is that the pressure received in the feet may send signals that 'balance' the nervous system or release chemicals such as
endorphins that reduce stress and pain. These hypotheses are rejected by the medical community, which cites a lack of scientific evidence and the well-tested
germ theory of disease. Reflexology's claim to manipulate energy (Qi) is unsupported by science; there is no
scientific evidence for the existence of life energy (Qi), "energy balance", "crystalline structures" or "
pathways" in the body. In
Trick or Treatment? Alternative Medicine on Trial,
Simon Singh states that if indeed the hands and feet "reflect" the internal organs, reflexology might be expected to explain how such "reflection" was derived from the process of
Darwinian natural selection, but Singh says that no argument or evidence has been adduced. ==Regulation==