I didn't do any supplements. The Water Fast works best if nothing but water is taken. Sometimes I chew gum or something for my breath. You don't want to be repulsive during a fast.
A juice fast after Water Fasting is a really nice way to break the fast. you will still be in ketosis for a few days after beginning juice, if you don't go overboard on the juice. 3 12-16 oz servings a day was what I aimed for. A shot or two of wheatgrass here and there is nice as well.
for my first year of trying to get rid of Hashimotos, I averaged one week of Water Fasting per month. Some fasts were two and one three week long. This resulted in about 100 days of fasting in one year.
My condition was much, much better. Many symptoms were pretty much gone, such as joint pain. I didn't need thyroid meds any more.
Now when I fast, I usually try to start with three days dry and then transition into a water fast. I get really tired dry fasting, so three to four days is all I can handle and still work.
My Hashimotos has flared up recently and I think it's due primarily to stress. there is a link to the adrenals and thyroid. Also, I haven't been fasting enough. Also, I stopped taking Iodine on a regular basis.
I think to get completely better I would need to do a complete fast in a stress-free environment. that's difficult when you have a mortgage and bills, etc.