I just did my first 90 hour fast. Had 3 very minor bouts of diarrhea. They were small and not disruptive, seemed more like a release valve than the kind you’re describing (a kind I used to experience quite often pre-Keto). Didn’t mind them at all.
I take magnesium citrate with my ketoaid but in doses far less than the amount the bottle says to induce a laxative effect. Maybe next time I’ll leave out the magnesium and see if I have any bouts at all.
I’m pondering getting magnesium through the skin via epsom salt baths (feet only for me, no bathtub) based on something Dr Fung said in a video about absorption rates. Need to do some more googling on it, though.
Seems like there’s a lot of variability in how people react. I wish you could find a clearer answer. Good luck.