Final answer:
The primary way the body loses heat is through evaporation cooling, which is significantly utilized during physical activity. Conduction, convection, and radiation are other mechanisms of heat exchange but play a secondary role compared to evaporation during active heat loss.
Step-by-step explanation:
The primary way the body loses heat is through evaporation cooling. This process is when heat is transferred by the evaporation of water, a mechanism especially important during physical activity. While resting, about 20 percent of heat loss occurs through evaporation, with more significant amounts lost during exercise.
Other mechanisms of heat exchange include conduction, where heat is transferred from one object to another through physical contact; convection, the transfer of heat to air or water as it passes over the skin; and radiation, the transfer of heat in the form of electromagnetic waves.