I've been doing some studying on the subject of prolonged fasting. The findings are fascinating. I'll post a few links for you to explore at your leisure.
I'm amazed at how many testimonials there are of people whose ailments and diseases disappeared by the simple act of going for a prolonged period of time without energy intake. New studies are appearing in recent times regarding the benefits of fasting to control diabetes and some degenerative brain diseases.
Upton Sinclair, American Pulitzer prize winning author, outspoken socialist and one-time Democratic nominee for the governorship of California, is one of the major contributors. It's a lengthy read, but many us have that much time and then some, so it won't do any harm.
Another link is a YouTube video of a TEDtalk (which I really enjoy) given by a scientist from the National Institute of Health and National Institute on Aging, given at Johns Hopkins University, if memory serves correctly. Fascinating information.
My final link is a report on an article published in the scientific journal Cell which demonstrates that fasting has been proven to improve, if not cure, diabetic conditions in laboratory animals. I read the research in Cell, as well, and it's highly technical. I'll post that link below the link to the article.
And for those of you who REALLY have lots of time to spare, the final link is bonus material. It's a religious pamphlet reporting numerous healings as the result of prayer and fasting. It's content is unabashedly religious and I've warned you ahead of time. If and when you comment, please be as respectful of those religious beliefs as you expect others to be of yours.
Now...Here we go...
Click here: This link opens an online version of Upton Sinclair's work, The Fasting Cure.
Click here: This link automatically downloads a PDF version of Upton Sinclair's work, The Fasting Cure.
Click here: This link opens the TEDx Talk at Johns Hopkins University by Mark Mattson about "Why Fasting Bolsters Brain Power".
Click here: This link opens the article published by abc.net.au/news/ reporting on the results published in the scientific journal Cell about the benefits of fasting in diabetic laboratory animals.

Click here: Here's the scientific mumbo jumbo published in Cell. I perused it.
Click here: Here's the religious pamphlet published by Franklin Hall. This link automatically downloads the file, so you'll have to open it from your downloads folder.
Enjoy!