The research revealed that “fasting for as little as three days can regenerate the entire immune system, even in the elderly .” It has applications for people whose immune systems have been decimated by chemotherapy, undermined by diseases like Multiple Sclerosis, or simply declined with age.
The findings are the results of two studies led by Professor Valter Longo of the USC Longevity Institute at the USC Leonard Davis School of Gerontology. How does the fasting-immune system connection work?
“It gives the ‘OK’ for stem cells to go ahead and begin proliferating and rebuild the entire system,” said Prof Longo…”And the good news is that the body got rid of the parts of the system that might be damaged or old, the inefficient parts, during the fasting. Now if you start with a system heavily damaged by chemotherapy or aging, fasting cycles can generate, literally, a new immune system .”
The body is forced to use stores of glucose and fat during prolonged fasting, but it also breaks down a significant portion of white blood cells. This depletion “triggers stem cell-based regeneration of new immune system cells .” It essentially shifts stem cells “from a dormant state into a state of self-renewal .”
So this could potentially be big news for chemotherapy patients, multiple sclerosis sufferers and the elderly. Mind you, fasting for long periods of time or going on a diet that mimics fasting is always something that should be approached with caution, and with the guidance of a suitable health professional. Longo et al used specific fasting and fast-mimicking diet protocols to achieve their results.
Still, they have turned up some very interesting findings in their quest to understand how the body reacts to fasting or fast-mimicking diet protocols.
So there you have it! There is certainly more to fasting than first meets the eye. The full studies can be found using the references below [6,7].
 Walia, A (2015), “Neuroscientist shows what fasting does to your brain,” Collective Evolution, http://www.collective-evolution.com/2015/12/11/neuroscientist-shows-what-fasting-does-to-your-brain-why-big-pharma-wont-study-it/ retrieved 21 March 2016
 Knapton, S (2014) “Fasting for three days can regenerate entire immune system, study finds,” The Telegraph, http://www.telegraph.co.uk/science/2016/03/12/fasting-for-three-days-can-regenerate-entire-immune-system-study/ retrieved 4 April 2017
 Wu, S (2014), “Fasting triggers stem cell regeneration of damaged, old immune system” University of Southern California News, https://news.usc.edu/63669/fasting-triggers-stem-cell-regeneration-of-damaged-old-immune-system/ retrieved 4 April 2017
 Gersema E (2016), “Fasting-like diet turns the immune system against cancer,” University of Southern California News, https://news.usc.edu/103972/fasting-like-diet-turns-the-immune-system-against-cancer/ retrieved 4 April 2017
 Gersema E (2016), “Diet that mimics fasting may also reduce multiple sclerosis symptoms,” University of Southern California News, https://news.usc.edu/101187/diet-that-mimics-fasting-may-also-reduce-multiple-sclerosis-symptoms/ retrieved 4 April 2017
 Cheng, C.-W., Adams, G. B., Perin, L., Wei, M., Zhou, X., Lam, B. S., … Longo, V. D. (2014). Prolonged Fasting reduces IGF-1/PKA to promote hematopoietic stem cell-based regeneration and reverse immunosuppression. Cell Stem Cell, 14(6), 810–823. http://doi.org/10.1016/j.stem.2014.04.014
 Brandhorst S, Choi I, Wei M, Cheng C, Sedrakyan S, Navarrete G, Dubeau L, Yap L, Park R, Vinciguerra M, Di Biase S, Mirzaei H, Mirisola M, Childress P, Ji L, Groshen S, Penna F, Odetti P, Perin L, Conti P, Ikeno Y, Kennedy B, Cohen P, Morgan T, Dorff T, and Longo V (2015), “A periodic diet that mimics fasting promotes multi-system regeneration, enhanced cognitive performance and healthspan,” Cell Metabolism, http://www.cell.com/cell-metabolism/pdfExtended/S1550-4131(15)00224-7 retrieved 4 April 2017