That's the Ana boot camp diet or anorexic boot camp diet. Some people call it either one. Lasts for 50 day, you eat no more than 800 calories a day usually less. And on some days you'll fast, or not eat anything. There are 5 days that you'll fast or not eat anything for the day. It tricks your metabolism and you'll loose weight. Most people don't like it because it's the beginning of anorexia or can lead into someone being anorexic as it did to me. After you're done with the diet you're supposed to go back to a normal eating routine slowly so you won't get sick or anything, so yeah.. That's the ABC diet. You could just look it up. It used to be on tumblr not sure if it still is, and it's all over the Internet. (: