Wearable technology has emerged as a hot topic in contemporary years around the globe and the interest in this sector continues to develop and will dominate in the future as well. This research work presents a microstrip-based multi-band monopole antenna for body wearable wireless devices (WWD) used for various body centric wireless communication applications. The designed antenna works at multi bands resonating at 1.8, 2.4, 5.0 and 8.9 GHz covering wireless and UWB based communication technologies. The electromagnetic (EM) effects of radiation absorption are investigated in terms of specific absorption rate and its biological manifestation as heating effect. EM computations and measurements are used to analyze the biological effects when placed on different sites on the body. Thermal effects for short term exposures and steady state conditions are evaluated using analytical methods. Experimental techniques using infrared thermography has been used for finding out the temperature elevation at three specific regions of the body. Simulated, analytical and experimental results of the heating effect are compared and are in good agreement. Further, the rise in temperature is found to be compliant with international safety regulations.