So, I used to be a marathon runner. I kind of use the same diet before a fast that I used before a marathon.
Tons of water, best if splashes of juice inside so it doesn’t just flow right through you.
Carbs carbs carbs. Bagel for breakfast, Pasta dinner. Carbs are the first the body digests, and the easiest. If you carb load before an extreme excercise, the energy stores are ready to be absorbed and the body spreads the energy out longer for absorption.
I truly don’t know if this works the same with a fast, because fasting is not a high calorie burning activity. But something about it makes sense to me and it does help me in the long run.
PS. Another tip is to take a caffiene pill in the morning, if you are a coffee drinker. It’s really amazing.