There are good diets and then there are bad diets. The 500 calories diet is another one of those fad diets that has gained popularity over time, but at the end of the day, what damage is a diet like this having on your body?
A normal low calorie diet is one which caters for 1200 calories per day. 500 calories is less than half that so you can only imagine what sort of an impact that level of calories would have on your body. The whole idea of embarking on a low calorie diet of 1200 calories a day would be to lose weight and lose weight quickly. To reduce this even further to 500 calories a day is fraught with danger and if you were contemplating doing this, you should first visit your doctor or dietician to get a clearance for this step. It would be extremely dangerous to do this without supervision.