My fasts last year to lose the 40 of my 140 kgs were short to medium length. I started with a 5 day dry fast, then went to a 14 day Water Fast and then did a series of dry fasts, the longest being seven days. I also did a one or two more ten or eleven day fasts as well. Over three months I fasted half the days and the other half I ate mostly raw foods- more than 90% raw.
Starting out obese and with Depression as well and being a single father having to keep up with two active young kids the duration of the fasts was mostly cut short due to my wanting to stay active with my children. They were my main motivation for fasting anyway, just wanting to be able to run around the park with them was enough to keep me going. I had stopped doing that when I nearly broke my coccyx sliding down a slide many years ago due to my being too big to take the fall. Since then I have stayed raw and kept fasting but no more than 5 days at a time since. I have kept the weight that I lost off but not been able to finish the job so far. My 'failure' to complete what I started isn't really a problem in itself as I am quite fit and healthy as I am now, but I do continue to try- I am on day three of my current fast.
The challenges I have to face right now are just rather close to impossible so it's been enough just to maintain what I had already gained. It would be nice to go the last mile though at some stage! :)
Before I became obese I also fasted for 30 days while working and doing strenuous karate classes each week. That was far easier than fasting while obese and having lived on junk food for many years prior!
My ex thought stretch marks were permanent too. She used to try heaps of topical remedies but nothing really effected them at all. I had them on my belly and the inside of my upper arms.