Less than 1200 Cals a day??

You need to use the harris benedict to calculate your actual daily needs. because you're not in a coma!
I'm guessing you're around the same weight as me as I'm 5'2 and:

Your estimated BMR is: 1,249 calories/day*

So using the harris benedict equation:
If you are sedentary (little or no exercise) : Calorie-Calculation = BMR x 1.2
If you are lightly active (light exercise/sports 1-3 days/week) : Calorie-Calculation = BMR x 1.375
If you are moderatetely active (moderate exercise/sports 3-5 days/week) : Calorie-Calculation = BMR x 1.55
If you are very active (hard exercise/sports 6-7 days a week) : Calorie-Calculation = BMR x 1.725
If you are extra active (very hard exercise/sports & physical job or 2x training) : Calorie-Calculation = BMR x 1.9

So for you (for example), 1225 x 1.2 (if you are sedentary) = 1470. So to reduce by 300 calories a day, you would be at 1170. I would round it up to 1200. This is without exercise, of course. If you're going to burn 100 calories through exercise, you would eat 1300/day.

I'm 5'2, I work out 6 times a week and I eat around 1300 calories. I tried 1200 and felt way too hungry all the time.

Heya,

I'm no expert at this and I could be giving terrible advice, but here's what I'm thinking...

I'm about the same height, I'm 5'3 and am with a similar metabolic rate given on the application, though I believe that mine is in reality faster running than the program judges for. You can't always accurately judge how much every person should consume, as everyones bodies run differently and we all have varying body types and factors. For example...if I put my BMI into a computer it would probably say I'm underweight, though I know for a fact I'm not. I have a fairly average body fat ratio - it's just the way I'm built. Very small frame.

I think a lot of the time you need to make an educated guess regarding the way your body responds to food and excercise. Under 900 calories to consume does seem really low - I tend to eat around 1200-1400 calories a day (and sometimes overeat!) but I work it down with cardio and strength training. My goal is to shift my body fat percentage also, so I'll be spending a lot of time working on my large muscle groups and trying to burn away the fat while I'm at it.

Also remember that there are certain foods high in calories that are actually very good for you and necessary for you to function. Things like snacking on almonds, or having a pre-workout protein shake (if you're so inclined!) might blow out a calorie intake for a day, but they're doing you good in the long run.

I think it's not all about exact numbers in the end, but this program is a really good guide and a fantastic way to stick to a healthy routine and watch what you're doing each day. I think that if you're feeling really lost, definitely talk to someone experienced, a personal trainer, nutritionist or doctor. I'm sure they'll be able to nut things out for you. I'm just lucky my partner is a health freak!