Answer:During aerobic respiration, mitochondria harvest only around 40% of total chemical energy available in a molecule (say, glucose) in form of ATP, the rest being dissipated as heat.
The rate at which the body loses heat depends on the temperature difference between the skin and the environment. In the cold, therefore, the aim is to reduce the skin temperature as much as possible, whereas in the heat the skin temperature should be as high as possible.
