Hey, just thought I would throw in my two cents, since this was popping up on google searches for me, that probably means others will read it.
Long story short: Electrolytes worked for me.
I did a 30 day Water Fast about 2 years ago which went great. super hard first two weeks but then I got a blast of energy. Worked full time plus a part time job the whole time. No issues.
Currently on day 36 of a 40 day water fast. I never got the same hit of energy that I did last time. It went up a bit around 18, but on about day 25 I started having very mild nausea that was super annoying. I also started getting even more drained of energy, with considerably more lethargy that I had prior to that. Thankfully I work for myself now and could afford to rest more. On day 30, I threw up bile the first time. I didn't panic, but it got worse, until I couldn't really sit upright without expecting to throw up within a half hour. I threw up 3-5 times a day for the next five days, and most days I threw up the water I had drunk that day.
I could tell I was getting dehydrated (admittedly I had been struggling to make myself drink enough the entire time) and was worried that if something didn't change, I would become critically dehydrated. What was odd, was that there were no typical dehydration symptoms except for a dry mouth and slightly dry skin. I was constantly exhausted and had no motivation to do anything. After the fifth day of keeping very little water down, I decided to try electrolytes as per this post. If that didn't work, I was going to break the fast with juice for the last 5 days.
I chose EmergenC for its wide range of vitamins and electrolytes and that it could be mixed with water and diluted. It does have 35 calories. I decided that was perfectly acceptable, given that I was either going to be seriously hurting myself or breaking the fast anyways (yes, I've read all about healing crises and such, see the bottom for my response to that). I took one packet around 7:30pm on day 35. I had waves of strong (but different) nausea for awhile, but held it down. My stomach and intestines then went through a rather ridiculous bout of gurgling for nearly two hours while I watched a movie. I then drank about 16oz of water and kept it down. I did have some mild nausea several times, but nothing like before. By the end of the movie, I already felt better.
I didn't sleep well and woke up feeling terrible. I had a major headache, dry eyes, dry mouth, and almost no nausea. But, despite that, it felt like my body was finally signaling me that I needed water, where it hadn't been doing so before (I had to force it down). I had another EmergenC first thing, which made me a little nauseous, but not bad, and drank about 20oz over the next two hours. I sat upright all morning with no vomiting. Then I got up, cleaned up, shaved, showered, and have been on my computer for awhile. I had another EmergenC around 1 with no nausea.
I don't know if the 35 calories have broken the fast, but I know my body was happy to get what I gave it. I've got more energy and motivation than I've had in a week. Still weak, still tired, but vastly improved. This feels much more natural than the zero symptoms and deep fatigue I was feeling before. I'm also functional again.
Quick note: I'm 29, Male, and started this fast at 300lbs (I'm not weighing myself during the fast). Was eating a pretty healthy, cook at home, whole foods type diet for several months before the fast, and doing my best to make good choices before that, so I wasn't overly toxic, and the first two weeks were much more mild than my first fast.
As far as healing crises, I agree that the body does that, I've been through some strange aches, pains, and general issues during my two major fasts. Old wounds hurting, allergies going nuts, back pain, etc. All generally last about three days and I just let them work it out. This was different. My body wasn't responding to anything I did to it. It wasn't improving, it wasn't keeping water down, and it was getting worse. I'm no doctor, but the sudden surge of dehydration symptoms after I had the electrolytes and vitamins tells me that something wasn't right in my body. Now that I'm able to drink enough water again, the headache goes away when I get enough and comes back if I don't. Thats normal. I've got a few other strange abdominal sensations going on too, but it feels like things are moving around, where they definitely weren't before. I never had a major "Clean out" bowel movement this fast (I can't remember about the last fast). We will see what happens with the rest of the fast. I can't promise to update this, but if I think about it, I'll try.
Just wanted to inform people of my experience with the electrolytes, and say a hearty thank you to fastingforlife. I wasn't quite ready to break the fast (I'm doing it for religious purposes primarily). I did turn on alerts for replies to this, and I'm happy to answer questions.