In this paper, we propose a time synchronization protocol specific for Body Area Networks (BAN). The diversity of hardware on which sensors will be deployed, the need for energy efficiency and the degree of accuracy required by different applications, are constraints that are not always addressed in current synchronization schemes. Using the broadcast message exchange scheme from FTSP we introduce the ability for the node to decide when to resynchronize, based on a maximum error and the clock drift, which can differ for each type of sensor. The node can therefore, dynamically adapt its synchronization period thus saving energy while keeping accurate. We use a weighted moving average filter to compensate for clock drift, where the weight can be adjusted to improve the estimation quality. The protocol is design to support a star network topology and the IEEE 802.15 Task Group 6 guidelines.