I am now in the habit of fasting every month.
Last month I did a longer (five-day) fast which I worked in with eating no fibre before a colonoscopy.
They removed an adenoma polyp (non-malignant) which had shrunk due to the fast. (My stools had been "D" or crescent-shaped, as the polyp had been almost blocking the sigmoid (the bit of colon that connects the descending colon to the rectum).
Monthly 68-hour fasts are now routine for me, so I expect no drama... but watch this space for updates.