I've done the 500 calorie thing. I was taking in 1200 cal's a day but doing an rpm (spin) class and that knocked me down to 500cals.

Just eating 500cals a day is not good for you hun! Up your calories for your own health and maybe up the exercise.

The main thing is to look after your health and as long as you eat right and do exercise you will drop the weight in no time!