Increasing demand for real-time personalized healthcare and continuous activity monitoring has been accompanied by an ever-expanding number of wearable and implantable sensors that localize to nodes across the human body. Such sensing nodes can coalesce to form battery-free local body area networks that enhance activity monitoring by reducing system size and battery reliance and enable seamless communication among the sensors and a local hub (such as a smartphone). Here, we propose an epidermal magnetic metamaterial made from flexible resonator arrays conformally fixed on skin, forming a nearfield communication (NFC)-based metamaterial network to propagate magneto-inductive waves across the human body parts. We demonstrate wireless powering and signaling from/to battery-free sensors placed anywhere close to the network under various routine conditions and activities such as wetting and mechanical distresses.