
I agree with the others. This doesn't sound like a healthy reaction to a "bad" day. Remember that although 2000 calories may sound like a lot to a dieter, this is actually the recommended daily allowance for women who are not dieting. It is not actually a bad number to hit every now and then.
There is a lot of debate about fasting, some people are for it and others against it. I do tend to lean towards being against it, and for someone with your history of anorexia, it could be very dangerous for you to allow yourself to get into a habit of fasting. Please think about consulting a doctor, nutritionist or even counsellor before you do any fasting. I don't know you so I am not the best person to comment, but I get the feeling from your post that the way you deal with overeating and then fasting is not a normal reaction, and does possibly stem from your previous eating disorder.
Please be careful

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Just remember, fasting can upset the body's metabolism and you could actually put on more weight when you come out of the fast. A balanced, low-calorie diet with lots of exercise is still the best way to reduce and maintain a good weight and figure.
Have you thought about calorie cycling rather than fasting? That could be far more effective for you.