Wireless Body Area Network (WBAN) is one of the latest technologies in wireless communication, and is being widely studied for its applications in military, healthcare, sports, and other sectors. In this paper transmission coefficients S21 are measured for several on-body radio channels and the effects of two different body structures on path loss coefficients are determined. Considering static position of body in the laboratory, measurements are carried out for Line-of-Sight (LOS) and Non-Line-of-Sight (NLOS) radio channels by using two identical tri-slot microstrip patch antennas of 2.48 GHz connected with a vector network analyzer (VNA). Using necessary statistical method path loss coefficients are calculated from the measured data and compared to explore the effect of different types of bodies on WBAN performance. Finally, we have tried to justify the reasons for considering LOS and NLOS measurements separately in establishing an accurate channel model for BAN.