Good question. I think it's a hack: on the one hand it supposedly frees up energy from digestion to concentrate on prayer or repentance, on the other hand I don't feel the thinking is as deep: it locks one into a survival mode thinking - which may or may not help the spiritual practice. Like driving when tired: only the needed parts of the brain that are required switch on. So concentration improves, but the thinking is not as deep (that is when hunger pangs don't distract!)
Supposedly fasting also promotes longevity by affecting gene expression, and the same effects can be obtained from resveratrol. Additionally, small fasts are meant boost human growth hormone, hence the warrior diet: only eating at night. Fasting before and after exercise boosts it the most.
A doctor I once knew said the reason they put new doctors on such long shifts is so they stop thinking and behave more according to text book.
Supposedly fasting also promotes longevity by affecting gene expression, and the same effects can be obtained from resveratrol. Additionally, small fasts are meant boost human growth hormone, hence the warrior diet: only eating at night. Fasting before and after exercise boosts it the most.
A doctor I once knew said the reason they put new doctors on such long shifts is so they stop thinking and behave more according to text book.
Anyhow, check out this article/podcast about a fasting, and in particular regarding someone grossly obese for 1 year and 17 days: http://www.abc.net.au/science/articles/2012/07/24/3549931.ht...
"His weight dropped from 207 kilograms to 82 kilograms. Some five years later, he had regained only 7 kilograms."
I wonder how mentally active he was during that time.