WHO WANTS TO START A WATER FAST WITH ME!? (question about heart palpitations from fasting)

Hi, I did a Water Fast the end of january, I went from 132 lbs to 115 but gained 5 back. I wanted to do it for 21 days but only made it to 11 because I started getting really severe heart palpitations and it really scared me so I ended the fast there, if someone could tell me how I can prevent that from happening this time that would be great as I would like to fast again and reach my goal of 21+ days.
I am doing this to gain better health, clear my skin and weight loss as I gained back some weight from the first fast. right now I am 5'9 and right now Im 125 lbs but 5 of that is water weight from binging last night, how much weight would I lose on a 21 day fast? and please no lectures because I know I am not fat lol but I know that fat carries toxins.

If anyone wants to fast with me let me know :)