Fasting used to be a way of life, just not by choice. Now a study at the University of Southern California has shown that cycles of fasting can not only protect against immune system damage but also induce immune system regeneration.
In studies in both mice and human clinical trials involving patients receiving chemotherapy, it was noticed that white blood cell counts went down with prolonged fasting, then back up with re-feeding.
According to Dr Longo of USC, when you starve, the system tries to save energy and one of the ways it can do this is to recycle a lot of immune cells that are not needed, especially those that may be damaged. During each cycle of fasting this depletion induces changes that trigger stem cell based regeneration of new immune cells. For systems that are damaged by chemotherapy or ageing, this can generate a new immune system.