Here's one thought on IF.
Recently I was diagnosed with IBD, I was in a bad way, 16 really unpleasant, rushed visits to the smallest room. This was something I'd had on and off for many years. Anyway, I had to do something and refused the meds, so I thought I'd give my guts a rest, let them heal was my thought, seemed logical.
I did a 3 day fast, that was 2 months ago, I've just had my results back from a calprotectin test (the marker for IBD) and my doctor can find zero evidence of IBD, she's in shock! my calprotectin score was 6 mg/g, she said that's about the best score she's seen in anyone. I'll be doing this 3 day fast once every month.