I am not an expert, I'm on Day 2 of my second ever fast, I previously fasted for 19 days about 1.5 years ago. I didn't have leaky gut, but I did have some stomach/digestion/heartburn issues that caused some unpleasant symptoms. My fast resolved that issue and I haven't had a problem since.
And again, not an expert, but that was my experience, all the best to you.