I personally don't think that eating less than 1000 kcal per day is healthy for a person who also does 1 hour cardio fitness per day. Neither is aiming for losing 2 kg per week. If you lose that much weight, you take out an extreme amount of fat. Unfortunately, your body doesn't only use fat to store reserve energy. Your body also uses this fat to store some harmful substances your body can't get rid off easily. Losing a lot of fat in a short time will "set these harmful substances free" and your body now needs to get rid of it in another way. Usually this is more difficult than storing it in your fat or liver.
If you now lose 2 kg weight every week, you will damage your body with dealing with these harmful substances in a large quantity. Of course, you might not have so much of this stuff in your body, since you only eat healthy stuff and don't live in a western society. However, if you are, like me, living in Europe or the US, you will have some unusual stuff floating around in your body coming from processed food. Your body will probably have stored this in your fat tissue a lot. When you can lose 2 kg a week, you might have a multitude of that too much on your hips.
Please, read the article that Berin Loritsch gave as a comment. Calculate your calorie need and try to have your intake between 500 and 750 kcal below that. You will then have a healthy weight loss.