The term is autolysis, which is in essence self-cannabalism, and is, as Livingwater pointed out, where the body gobbles up all the nasty tumors, cysts, dead cells, bad bacteria and so on... 'Tis another reason why a juice faster need not worry about their protein intake while fasting... The body happily chomps down on plenty of protein during detox.
Autolysis
Love what the body knows to do when left to its own devises... amazing.