Try a short 1-2 day fast first, no need to do a long one right away. It's important to be able to refeed slowly and in my experience doing longer ones out the gate I had trouble not over eating on refeeding.
I swear after fasting and being more sensitive to food and water I notice a chemical taste in purified water. I recommend spring water as it tastes crystal clean.
On a previous longer fast 10 days, my calves started to get really sore and tight, as if they were pushing things out. I never had issues with my calves so I found it odd.