I know the question wasn't directed at me but I reckon pullups, hanging and "supermans" are great set of exercises for the back. I don't think squats directly work on the back, but they're definitely good for core strength. Am keen to hear others' thoughts and recommendations on this though, too.

I've done a few 24-72h fasts here and there, but not lately and not too often. I do (generally) eat once per day though (it's not that easy here in Estonia tho with lower quality food & smaller portions compared to Australia and New Zealand)