I believe that it has a good effect due to not exacerbating any present issues. Fasting also fights inflammation. I find that when i fast, unlike any other time, i am no longer desensitized in my stomach area and can tune into what is happening there. I think a lot of times leaky gut gets to the point where peoples stomachs are numb and just accumulating more bad bacteria etc. So fasting is good, i think using probiotics along with fasting and taking aloe vera gel pills, help the intestinal lining and gut microbiome