Waterfasting with supplements

Hi! Here is the deal. Im a soon to be 19 young man from Norway, and i was at about 80Kilograms last june 2014 before i visitied my family in Pennsylvania. My height is now 168cm ish and my weight now is 120kilograms. Before i visited the states i was about to start to cut(since i was bulking). But i didn't have time so i thought i could do it in the states. But when i arrived in the states i was so shocked at how good the food was there, so i ate and ate and ate.. and since i was staying in Lancaster Pa, there were so hard for me to get the gym because my aunt wouldn't let me borrow her car, and on the top of that i wasn't so motivated to workout. 2 months later i return back home to Norway, weighing 95kilograms. But i was still not motivated. Now, 7 months later im at 120kilograms... BUT! IM MOTIVATED! I have done alot lf pure Water Fasting before.. 3 -12 days.. i recently broke my 21-42 days Water Fast on day 8 this week because i just couldn't bare the nasty taste in my mouth and i was tired of feeling tired lol. So what im tryina ask now is: if i start a Water Fast from monday, but takong vitamons, minerals and caffein pills/Pre workout.. will my body be able to heal my stretch marks and some scars? Or do i need to do a pure Water Fast for my body to heal the stretch marks?

And since im tthinking about losing all that i have gained and go down to 80kilograms or less in 4 months, then i still think that my skin will tighten fast anyways because 1: im still young. 2: im on a fast (insulin drops and Human growth hormone increases very much) which has the job to produce more collagen whoch will help with my skin. 3: i haven't been ao overweight for so long either. What dl you think? Will my body heal? And will my skin tighten fast?

Thanks!