In modern mobile networks, users increasingly share their location with third-parties in return for location-based services. In this way, users obtain services customized to their location. Yet, such communications leak location information about users. Even if users make use of pseudonyms, the operators of location-based services may be able to identify them and thus affect their privacy. In this paper, we provide an analysis of the erosion of privacy caused by the use of location-based services. To do so, we experiment with real mobility traces and measure the dynamics of user privacy. This paper thus details and quantifies the privacy risks induced by the use of location-based services.