some guys at the gym told me wearing a weight belt makes would give me a nice v shape looking,supossing it's true, how about when you stop using it often, does it go back to it's normal size?
That makes no sense. I would not recommend using a belt for lifting anyways. When you do that you are not allowing your core to develop and strengthen. You want to lift raw. This also goes for things like gloves, wraps, straps, etc..... learn to lift raw.
When you train WITHOUT a belt, you indirectly train your abdominal muscles to stabilize yourself when doing the exercises. Training without a belt will make your abs stronger and bring your midsection in.
I never train with a belt and my waist is wasp like. I tell all my clients to not use a belt unless absolutely necessary. Most of them have noticed their waist circumference decrease when they stopped using the belt.