I Am A Female Who Is 5 Feet 5 And Weighs 115 Pounds. If I Were To Fast For 12 Days How Much Weight Would I Lose?

Well it depends upon your metabolism. Some people lose faster and some lose at slower speed. But ideally it is healthy to reduce 2 to 3 kg -- 4 to 6 pounds--- in one month. If you lose more than it is not good for your health. You will feel weakness and you may become lazy and I am sure you don't want that.
So eat healthy and do regular exercise to remain fit in long run.

Loosing weight by fasting depends upon you body's metabolic rate. It also require consultation with doctor. Because this way of loosing weight will not be permanent and will cause many side effects. I advise you to visit a dietitian before doing this and act upon his advise and start weight reducing exercises.

If you are 5'5" and 115 lbs., you are already thin and do not need to lose any more weight.
Suggest that you do not fast, because that will slow your metabolism down to a crawl, or shut it down completely. Which will cause you problems in the future, once you start to eat normally again.
Check on-line, etc., for a height and weight chart to see what your average weight should be.

Fasting will only mean as soon as you have finished you will put all the weight back on again that you lost a sensible eating plan where you lose a couple of pound a week is what you need you are not over weight so try and look after your body metabolism take care

You are actually too thin.  You must look like a stick.

First off, at 5'5 and 115 pounds, you are already well within the normal weight range for someone your height.

The normal range is 114 - 144 pounds.

Considering that alone, it doesn't seem like you would have too much left to lose.

Nevertheless, lets look at what would happen:

At 115 pounds, the amount of calories your body would need to maintain it's current weight would be: Bodyweight (115) x 15 = 1,725 calories/day.

If you were not eating anything at all, and only drinking water, you'd be at a daily deficit of 1,725 calories.

It takes 3,500 calories to burn 1 pound...so assuming you somehow managed to eat absolutely nothing for 12 days, that is:

1,725 x 12 = 20,700 / 3,500 = 5.9 pounds.

Chances are you'd loose a few pounds of water weight as well, so I would guess between 6-9 pounds.

If you're going to fast, you should look into intermittent fasting, which has you fasting at most for 2 24 hour periods within 1 week...

Another variation has you fasting for 16 hours each day and fitting all your meals in the remaining 8 hour window.

Bottom line though, don't look for any quick fix that will put your health at risk...it won't result in any long term results anyways.  Find a proven diet/exercise routine that works, stick to it and implement it to a T.

I don't know about you but I am anorexic and have been struggling with it and I eat less than 200 calories a day and I lose about 1 pound a day.