I dropped from 140 lbs to 110 lbs in a month. I'm 5'4 female, and a 'skinny' weight for me is about 130 lbs as I am fairly muscular.
I used to want to look like a skeleton, I had no medical supervision and this was probably one of my worst eating disorder periods, the other being at college where I ate a microwaved apple or orange and 2 cups of broccoli / carrots only every day, for most of my freshman/sophmore year.
When I was ill, I knew I what I was doing with a disorder in mind, but I didn't admit it to anyone outside of me. I think most people who have an eating disorder know they have it inside, it's just something kept carefully secret.
I've been in recovery for about 2 years now, with healthy thoughts and no food restriction, excess exercising, starvation or purging. When I was sick I really didn't care if I died, as I have major depressive disorder comorbid, which I continue to have more difficulty beating than I did the eating disorder. I've fainted from fasting and I've been hospitalized from starvation. It's hell, pretty much.
I think it's important to take a step back from whatever the goal of these diets are, and look at the bigger picture. My weight only varied between 30 lbs over 15 or so years, and it controlled me entirely. It made me have to put a lot of my life on hold, when I had to focus what little energy I had towards getting better. I would really recommend anyone take a more careful, therapeutic look at their life if the above sounds tempting, and they find themselves going into cycles of fasting and 'losing' control over how they manage their diet.
After 3 days, I could easily do a week, and I managed to do a 30 day fast one year.
I don't recall feeling high, I just remember a lot of laying down, dreaming and thinking about food, baking, and not doing much of anything else.
I really rather prefer being able to eat everything I want, and spend 2-3 hours a week at the gym. But my weight has gone up by 10-15 lbs (and I have also aged from 17 years old to 29).
I can't say I'm the same size as when I was fasting, but I have a defined shape, whereas before I was bone and skinny fat.