I have to put in my two cents here. I use to be severly over weight at the 285 lb range. Through anorexia nervosa i lost a decent amount of weight and latter in life when i was already 185 lbs i restricted my coloric intake to less thana thousand calories a day quite often in the 700-800 calorie area. I dropped to 146lbs. I did this by caloric counting and journeling. Be cautious and know why you are tring to loose the weight try to identify the emotional reasonings for it. For me it was more than just the idealized weight form. I saw it as an escape at first then as a transental way of dealing with the intense pain in my life. (this was after the first boyfriend i had ever had physically abused me when i tried to break up with him) It seemed that as each lb dropped i was able to deal with one more thing in my life that i had stored as a negative. Because of my slowed down metabilism i was for once able to act singularly instead of rapidly and without focus as i had been all my life(i have adhd) I worked 3 different jobs as well as walked 6 miles a day. Luckily, I found myself at the end of it when i started eating alot again more healthy emotively for having done it. My body was however ravaged and muscle depletion is a problem for me now as i struggle with basic weight training. But i wanted to say that if you have an eating disorder be cautious of this approach.