Nice to see your experience with fasting. The details and documentation are much appreciated.
On a related but more general note, fasting on a semi-regular basis has been part of several Eastern cultures for ages (millenia). Folks have understood the benefits of fasting (both short- and long-term), and have incorporated the same into their culture/religion/life. I'm originally from India, and am a Hindu (religion). We have many festivals throughout the year (at least once a month on average), and people fast for many of them before breaking their fast with prayers (at least traditionally; present day habits vary). I myself am not as regular - I often celebrate the festivals by eating a lot . For some of these festivals, folks do a complete fast for 24 hours (even no water). Only fruits+water for 24 hours is more common, though. I try to do this sort of fasting occasionally (over the past few years). Also, I usually avoid eating anything till ~1 PM on Sundays (I drink water and coffee without sugar/cream - need the drug to read CC, sheesh!). I've not tracked any effects of these minor fasting efforts (good or bad). The game would be quite different if you're fasting while/as part of training for huge climbs, so I'd be curious how you incorporate the same into your future endeavors into the big hills.