will i lose 1 kg a week if i eat less than 1200 calories a day and burn 400 through exercise? (thats 800 calories i am consuming a day)?

There are a lot of factors that contribute to weight loss and what you are suggesting above is not healthy despite those factors. There are so many questions that need to be answered in order for anyone to give you a decent idea about what kind of nutrition and training program you should be following and what kind weight loss is achievable in any given period of time.

First off, NO ONE, male or female should be eating under 1200 calories. That is starvation and it will do nothing but bad things for you in the long term. It may help you lose some weight at first but it will do MAJOR damage to your metabolism. With that out of the way, the first thing you need to do is find out what your Basal Metabolic Rate (BMR) is. This can easily be acheived by googling "BMR calculator" and putting in basic information about yourself. Typically all you have to put in is your sex, your weight, and your height. Your BMR is a calculation of how many calories your body burns performing the actions it needs to, to keep you alive. So, basically your BMR tells you how many calories you would burn if you did absolutely nothing, like laying in bed all day nothing! That doesn't include any calories you burn walking or sitting or typing or even chewing gum! Once you know your BMR you can figure out how many calories you should be eating by multiplying your BMR by 7 (7 days in a week) and then subtracting 3500 from that number then dividing that number by 7. That will give you how many calories you should be eating daily. Through diet alone this will allow you to lose 1lb per week. If you exercise and burn 400-500 calories per day that should bring you to just about 1kg a week.

I hope all of this makes sense to you and I really hope you don't do what you've planned because it's incredibly unhealthy.

Best of Luck

- M