It is wrongly anticipated that the amount of fats burn in human body is related to the amount of sweating, particularly in hot months of the year. In this study, heat losses from human body are studied based on clothing habit, weather condition in Amman city, and the bio-heat transfer mechanisms. The heat losses from human body include breathing (evaporation), conduction, convection, and radiation mechanisms. It is shown that heat losses are largely prevailed by conduction and radiation compared with convection and breathing mechanisms in all months of the year. It is also realized that the heat loss by breathing air is totally depends on the dry bulb temperature of the ambient. The heat loss by convection mechanism depends on many parameters such as clothes temperature, Nusselt number, and heat convection coefficient. The heat loss by radiation mechanism depends mainly on temperature differences between clothes surface and ambient. From the results of this study, the human body losses more heat in spring and winter than summer and autumn. It is also concluded that human body burns more fats during winter and spring seasons than summer and autumn.