Fasting occasionally under supervision may have benefits, but it is nothing compared to maintaining a healthy balanced diet combined with exercise. If you really want to take care of yourself, do it every day - don't just save it for a fitness binge like this. Check out something like the anticancer book by the late Dr. David Servan-Schreiber or try out any diet high in veggies and low in processed foods, focussing on occasional high quality meats, eggs and fish. You will be a better hacker for it.