Fasting was one of the most memorable and shaping experiences of my life. I fasted for three days (72 hours of nothing but water) and observed so many interesting and fascinating things happening to my body each day: skin flare ups and subsequent clearings, changes in mouth and gut odour, periods of brain fog and brain clarity, cravings followed by complete loss of feeling of hunger. Every passing day had different effects. The most memorable was an astronomical improvement in my olefactory senses. By day two I was able to pick out the smell of individual ingredients in any dish being prepared in my vicinity. By day three, I lost the majority of my muscle mass.

The one and only time I ever did this was when I was young and in extremely good health (daily intense exercise, excellent diet, no health conditions). Slightly worried about doing it again today. Also, quite concerned having since learned that brain mass is the first stored energy source your body will go after during what is effectively starvation. Perhaps someone more knowledge on here can comment on how true that is.