I've been fasting for about 2 years now. I've done a couple of 5-days water fasts, and a few 7-days water fasts. The past 250 days I've been consistently following 16:8 and adding in a few 23:1's in there for good measure. I was healthy before I started, but have since then felt even better. My stomach feels calm, I sleep better, I feel stronger (even though I exercise less) and my overall focus has improved. This results in a better mental state, somehow calming my mind. I've been a practitioner of meditation before, but have not felt the need for it the past year. My body is calm and well-rested => my mind is mindful.
But the number 1 benefit of fasting (and all other non-conventional habits, such as cold showers in the morning), is mental resilience. Every time you realize that you perform well, if not even better, without food, you get a confidence boost. This effect compounds with time. I've found out that this in turn makes it easier to take on other habits as well, because your habit muscles are stronger now than before. Eating 5 meals a day is easy... eating 1 is hard => you grow a little if you manage to do it.