For example, consider the first law of thermodynamics, energy equals heat plus work. When fuel and air enter an engine the more energy converted to work, the less heat there is in the exhaust. When exercising, dress warmly. A thin t-shirt, as opposed to a sweatshirt, causes you to lose energy. A large amount of your body heat escapes into the atmosphere.
Heat energy is measured in calories.
Calories are part of what you ingest in order to gain weight. One of the functions of the skin is to serve as a radiator for the body, the reason elephants have large ears. Mac MacFarland, Mr. Hawaii 1963, once told me of an experiment with rabbits in which one ear of each rabbit was wrapped in wool and the other was left to flap in the winter cold. Through the winter the wrapped ear of each rabbit grew twice as long. Let's take each area and explain it.