> When you starve, the system tries to save energy, and one of the things it can do to save energy is to recycle a lot of the immune cells that are not needed, especially those that may be damaged

That's remarkable news. I'm waiting to see the counter-arguments though. Fasting for 3 days seems like stretching the limits a bit. Also it seems to imply that these 3days periods are repeatable over the course of a few months.