I don't eat anything but I don't lose weight?

I eat really a little last 5 days , I feel hungry all the time ( I read that when we are hungry we lose weight).

I don't eat any sweets , I eat mostly vegetables and I drink a lot of water .. I don't eat more than 500 calories per day.

But my weight didn't change even a little since this 5 days..

Why don't I lose weight if I don't eat?
I don't eat anything but I don't lose weight?
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