Recently saw this threaddiscussing water-fasting, and noticed a few other users mentioning they'd completed 30+ day fasts. There seemed to be a bit of interest in the results/changes/consequences for someone going zero-calories for extended periods of time. Figured I'd open a forum topic if anyone was interested in some more information.
From my experience, I started the 30 days at 96.1kg and reached 79.1kg on day 30. Using the data from a body composition scan at both the start and end of the fast, I discovered I lost around 60% fat and 40% muscle - which ended up much more than I was expecting. I also checked in with my GP regularly, and took blood tests before and after the fast for safety's sake.
If there's any questions, ask away!