I'm trying to fast with as little supplementation as possible exactly to give my body rest from years of non-stop (meat)-eating. I take fish oil for mood stabilization, vitamins not to get deficient in them and ZMA to sleep well. This doesn't distract me too much and I doubt it present any real work for my stomach.
I'm fasting longer than planned just because I feel so damn good and my mind is clearer than ever before. I do feel slight physical weakness in the morning, but I could still train, apparently. I've been so concerned with nourishing my body with food for so long, and it turned out that to nourish my mind, I need to fast. I've read in the past a lot about fasting helping the mind, but only now I got the proof.
I am dropping weight crazy fast though. 2 weeks ago (when caloric restriction/higher metabolism came unwillingly) I was 165. Now I'm 155 and feeling like fasting a full week (5 more days). I'm 24 and people started saying that I look 18... Haven't heard that in 4 years! If I drop down to 148, though, I'll stop and start eating again.