Very low calorie even fairly low calorie like 1000 maybe even 1500 depending on how obese you are is very hard to stick too. You are constantly hungry usually. Fasting is as you know much easier in that by day 2 or 3 most all physical hunger is gone.

Obviously you lose weight fastest on water. Some of that is water weight would say maybe close to 10 pounds or so in my case.I went from 260 to 217 lowest at end of 40 day fast. 31 water, 3 juice, 2 water and last 4 juice.
I started to get too dizzy and lightheaded near the end of the 31 days so switched over to juice. Energy was much much better on juice and no problems with the lightheadedness and dizzyness. Was araid was going ot pass out in middle of store ,walking around,etc. Scary.

I saw the scales go back up to 227 on refeed from salt and carbs. I have been staying around 222/223 for last week or so now. I do aerobics 5x week did them pre,during and post fast. 30 minutes fairly easy walking type of stuff on my treadmill or recumbent bike.

I started up weights 3x week post fast.

I also don't eat breakfast post fast and do EAT STOP EAT two times a week as well. I try to eat better,not snack much or if do make sure its healthy or low calorie snacking.

I may repeat shorter fasts maybe 14 day water with 3 juice pre and 3 after maybe in another few weeks. Fasting seems to work great for taking off the weight and seem to be able to maintain the loss not counting that 5 or 10 pound regain of water weight.

I am very happy to be down nearly 40 pounds and holding there. You can read my recent fast posts and did them pretty much daily on here and my refeed posts and updates.

Wife in contrast to me did 28 day juice fast.It was her first fast. Energy is pretty much normal on juice fast.
But weight loss is slower than water of course.
Water is fastest but energy can be very low and I did get that dizzyness and lightheadness and fainting feelings which got a lot worse after about 20 or so days. I posted some ideas on that in my fasting posts/blog.

Basically if you want to lose say 30lbs Water Fasting have to lose more like 40 actual which could take like 30 days.
Or break it up into a series of fasts.There is girl on youtube that did three nearly back to back 40 day water fasts. She dropped from 200 to 110 or so maybe lower and months later was still 120.Seemed to work good for her but 40 day water are brutal. I never want to do 40 day even combined water and juice again. 40 days on juice is easily doable but really boring and fasts longer than about 30 days really start to feel like you are fasting forever. 14 maybe 20 days is nice amount of time for me. Short fasts are kind of waste of time you have to keep going thru that first 2 or 3 of hunger so they are harder than just going thru once and keeping on going.