The field of remote health monitoring now includes technologies such as home and mobile health monitoring, tele-retinal imaging, tele-radiology, remote cardiac monitoring, video conferencing and sensors for remote diagnosis and treatment to patients. In this regard, implantable wireless body sensor networks (IWBSNs) have recently emerged as an important and growing research area. These implantable sensors are required to be reliable, very small, battery-operated, and capable of collecting data, processing it, and transmitting it wirelessly and efficiently. Since these devices are required to run with limited resources (energy, processing, and memory), their utility protocols (collecting, processing, and communication) should be designed carefully, not only to work reliably but, more importantly, to be resource-efficient. The life time of the embedded batteries associated with these sensor nodes varies from a few days to a few weeks as was described in a previous work by the authors. In this paper, we propose a novel technique which allows the implanted sensor nodes to communicate with a base station located outside the body efficiently by consuming the minimum amount of energy. Our proposed protocol allows the battery to last significantly longer even for years with a gain of up to 100's times of power saving. This will improve the quality of patient life, and reduce risk of infection resulting from frequent chirurgical operations needed to replace such implantable batteries. Also, a new time synchronization algorithm is briefly introduced in this work that is especially applicable to our proposed communication protocol.