Huge mistake. Water fasting is a breeze when done correctly and dangerous when not. The biggest risks are not supplementing the fundamental electrolytes because your body runs out of them in about 2-3 days and the second is not taking precautions to prevent refeeding syndrome. If you’d like to attempt another 3+ day fasting please read up on the fundamentals this time to ensure a pleasant experience. I love my headspace during an extended fasting, nothing quite like it. Two good sources to read up on this is the r/fasting subreddit’s wiki, (note the electrolyte and refeeding syndrome sections) and if you’d like something with more depth any/all of Dr. Jason Fung’s fasting books.
I beg to differ sir.. (full disclosure.. I am no doctor, nor expert in the subject, I've just read a lot of material, and I have survived 8 years of water fasting sans electrolytes) I've been water fasting for 7 days every 3 months for the past 8 years. For maximum health benefit, it is my humble OPINIOIN that we should not consume electrolytes, not until the 10th day of water fasting that is. When I waterfast, I want my entire GI-track to be on vacation (park everything). Furthermore, I don't want my biological cells being "distracted" by any substance in the blood stream. I want them consuming fat(no conversion energy) and doing severe spring cleaning. I want tissue repair in the entire GI-track, I want tissue repair in the liver, kidneys, heart... everywhere. I want damaged white blood cells to be flushed out (due to calorie restriction)<to be replaced with new cells once I start eating> renewed, I want I want senescent cells<zombie cells) to be flushed out. I strongly believe that introducing salts into the body will prevent optimal health benefits otherwise achieved. I would however, consider the introduction of a substance to break-down plaque in the veins while I fast, something that would break down fibrin, which is the glue holding plaque together, but I have not found a good natural fibrin-disolving substance.
https://www.reddit.com/r/fasting/wiki/fasting_in_a_nutshell