This has been posted before, but a good digestible source for the information in this comment is this two-video podcast series: https://www.foundmyfitness.com/e

This has been posted before, but a good digestible source for the information in this comment is this two-video podcast series: https://www.foundmyfitness.com/episodes/valter-longo https://www.foundmyfitness.com/episodes/valter-longo The studies you mention results of (like the 30% immune system culling in a 4-5 day fast) have only been published for mice so far afaik, but they're currently doing human studies. Also worth noting that one of the points Valter Longo makes quite strongly in these podcasts is that refeeding after the fast is at least as important as the fast itself.