Human beings have been involuntarily fasting for many thousands of years throughout history. During times of famine or lack, food was scarce and the human genome would have to have learned how to adapt to these conditions. Most religions incorporate some type of fasting into their teachings as a means of deepening their connection to our creator. Science however is only beginning to discover the benefits and physiological changes fasting has on our body, mind and soul.
https://www.youtube.com/watch?v=GvuNI6_BS0w