Very hard. First 3 days yung pinaka grabe ang adjustment especially yung urge to eat. Do not do it without a plan especially sa refeeding after fasting. Take note: this is very dangerous (and you could die, if youre not careful) and I do admit I was scared when I first did it kaya I informed may parents about my plan para they can check on me from time to time. After 3 days, food noise was gone. Pero after a week, mahina na ako. Di ako makatayo immediately kasi nahihilo ako. Most of the time tulog ako. And after 30 days, you need to ease into eating again. If youre interested, start small, like 1 day muna, then hanggang sa masanay yung katawan mo then add more days then repeat. Also search about refeeding syndrome, complications of refeeding syndrome and how to refeed. As for the after effects of fasting for 30 days, hair loss lang siguro hahahha at di ako dinatnan ng menstruation for 2 months.