I tried to fast one day last week. Couldn't do it :lol. I ended up eating mabye 500 calories tho - I can't see myself even doing it for one day, let alone 3 days. The reason I did it is because I overate the day before.
I don't knoe if there is a "safe" way...I mean one day of fasting doesn't do extreme harm to the body from what i read& experienced (just as long as you don't have a hectic day)...it's when you binge the next day and return to poor food habits...or if you decide to continue starving yourself is when I would say it's unsafe.
The most I've gone without food (just water and tonic water) was almost 2 weeks, but I recently read that the human body can only go without food for 2 weeks. Hmm...well maybe I should have placed a bet with these scientists.
I've done fasting for anxiety. Thought the method in which I fasted was a bit strange. I had a job interview in another state. I lost my appetite about 4 days previous due to being nervous. So I fasted. Two days into the fast, I felt much calmer. I was really surprised at how much my anxiety was reduced.
I've tried fasting when I'm not experiencing alot of anxiety, but its just too difficult.