You are a bundle of energy – literally. The number you see when you step on a scale is a measure of the energy that is stored in your body as fat, muscle, bones and the rest of the biological you. At some level most of us understand that the amount of food we eat in the form of calories has to equal the amount of energy we expend or the scale moves up or down. We gain weight if we eat and drink too much energy in the form of calories – a calorie is a measure of thermal (heat) energy needed to raise the temperature of a gram of water by I degree Celsius. If our energy intake is less than what we need to fuel our bodies, then we lose stored energy and that is measured as weight loss.
Anyone who has ever been on a weight loss/gain diet is well aware of the caloric value of popular foods. Carbohydrates and proteins contain 4 calories per gram, while energy-dense fat contains 9 calories. Fats even taste rich.
That’s basic thermo biology. But what do food calories have to do with the social issues surrounding energy?
Calories are fuel for work. In the post-industrial world we use the term “work” to mean a job such as being a taxi driver or the mental activity in an occupation such as accounting. But work has an earlier meaning as the physical labor in farming, hunting and the other activities needed to produce the means of human subsistence.
Until the industrial revolution and the application of inanimate machines to production, human and animal labor were the primary sources of work. (Physicists use work to refer similarly to energy acting as a force on, for example, an object).
So food is the primary fuel for human physical subsistence. It enables us to create shelter and clothing, raise our young, and search for more nutrients.
Those of us in affluent societies may not spend time searching for food because it is available seemingly everywhere - if we can afford it. It comes from the large cornucopias we call supermarkets, vending machines, even the local gasoline station where we can fuel our vehicles and ourselves at the same time. Time-intensive food search and preparation may indicate the presence of a foodie, not scarcity.