water cleanes

No.

Just eat your mfp prescribed calorie goal (or TDEE -20%, etc).

You probably also want to read this :http://www.myfitnesspal.com/topics/show/1080242-a-guide-to-get-you-started-on-your-path-to-sexypants .

Ok. I'm gona bite. You may be trolling but I'm too tired to argue with you so........... fuel your body, eat well, drink water, work out, get plenty of sleep, let go of stress and anxiety, take responsibility but forgive yourself. Do not look for a way to rectify 3 weeks of eating crap, you can't! It's done, move on. Do not starve yourself or do a water cleanse. Your body is pretty efficient of cleansing itself of toxins. If it wasn't you'd probably be on a dialysis machine. Start from right now, not tomorrow or next Monday. Make every decision from right now onwards based on how much better you will feel when you workout, choose the healthier food option, go to bed early, etc. Good luck.

There is an organ in your body called the liver, and another called the kidney (well technically kidneys because most people have two). The main purpose of these organs is to remove toxins from your body and they do this all day every day. Yes drinking more water on a regular basis will help your kidneys work more efficiently but there is no such thing as a "detox diet" or a "cleanse diet".
All you will do by drinking water and eating such a small amount every day is lose weight unhealthily which you will put back on once you start eating normally again - or you'll get to the point where you can't hack it anymore and crave a McDonalds (as a pen example) so bad you'll binge again, then feel guilty, then want to shift the weight gain immediately and this process will repeat. It's called yo-yo dieting.
Adopting a healthy lifestyle, where you eat and drink in moderation is the ideal way to lose weight at a slow but steady rate (ideal being 1-2lb per week) and will help prevent bingeing and a gain in weight.
You need to know your numbers and find out what your basal metabolic rate is (what you burn by existing and doing nothing) it is recommended by many to not eat below thus number. Then find out your total daily energy expenditure (TDEE - how much you burn based on your daily activities). Once you know that number you can reduce it by 10-20% to give you the number of calories you should consumer per day to lose approx 1-2lb per week.
I find a website called scoobys workshop to have a good calorie calculator - google it and you should find it.
I really hope that you listen to the advice being given to you and take heed of the many successful people on this site who have lost weight by following the above strategy as opposed to looking for a quick fix to assuage your guilt and get instant success, because that won't happen. Weight loss is hard - mentally much more more than physically and if you're not prepared for tough times and the occasional fall of the wagon you won't succeed.

Edit for spelling

Hmm... it worked for Ace Ventura. Anyway, poop, pee, and you're cleansed!

I think you may benefit more from a refrigerator and cupboards cleanse.

Not to mention, how do you feel your skin and face will look without any nutrition coming in at all?

I used to be a part of an extremist church, and we would fast for days on end to show our devotion to Jesus (thank goodness I left). That being said, it tended to help my skin and breakouts.

It just really isn't worth though, since you're taxing your body far beyond it's capabilities. Coming from somebody who is recovering from BED, I can tell you with MUCH confidence that the above people are right. Restriction only leads to episodes of reactive eating/over-eating, and neglecting to deal with the emotional reasons as to why you're using food to cope will only worsen the problem, Times ten.

PS. Your liver does all the cleansing you need. That's why it exists.