Why Most People Don't Exercise Regularly: The Law of Conservation of Energy

People cite all kinds of excuses for not exercising as much as they should, with the most common one being lack of time. While this is true for some, it doesn’t fully answer the question as to why so many don’t like to exercise and, like other forms of work, avoid it like the plague. I have a theory as to why this behavior is so prevalent among most people (and, really, all animals) and always has been. Borrowing a scientific term, I call it the conservation of energy. In physics, the law of conservation of energy states that energy can neither be created nor destroyed. Energy can be converted from one form to another, but the amount of energy in a closed system remains constant. The food we eat contains energy that is either converted into glucose for immediate energy or stored as fat for use when incoming energy (food) is low. The amount of fat we have depends upon the balance of energy coming in, in the form of food, versus the amount of energy we use, in the form of work, exercise, metabolism, and other bodily functions like breathing, which keeps us alive. Throughout this complicated process, though, the amount of energy doesn’t change.

Humans, like other animals, conserve energy primarily due to the fact that our lives depend upon this precarious balance between calories in versus calories used. I contend that our bodies have been programmed, via evolution, to not waste energy. From the beginning of human history we have had to expend energy gathering energy, i.e. food to eat and fuel to keep us warm. There were times when food and fuel were scarce, and therefore our energy stores dwindled to dangerously low levels. In essence, the success of the human species has been about pursuing, using, and conserving energy. Due to periodic famines and the inconsistency of food sources, our bodies became very efficient at storing energy – fat. From that standpoint, it would have been unwise to waste that stored energy on activities that did not result in the acquisition of more energy. And that’s why people today avoid all excess movement. Over the millennia, these behaviors became embedded deeply in our genetic makeup. Now still lurking in our unconscious, our brains tell us that exercise is a waste of valuable energy. It also explains why most people, in general, are somewhat lazy, due again to conservation of energy. We see the same behaviors throughout the animal kingdom. Predators expend most of their energy stalking and running down their prey. When they are not hunting, they are laying around. Just observe your cat or dog for a while, and you’ll see what I mean. You’ve no doubt heard how busy bees are. As it turns out, bees are idle about 70 percent of the time. It appears as though energy conservation within the animal kingdom is a natural phenomenon, one that impacts humans as much as any other species.

A second major consideration of the law of conservation of energy involves the body’s preference to maintain homeostasis, which centers around a balance of energy out versus energy in. In other words, the body attempts to maintain a constant weight. That’s why your metabolism decreases in response to a drastic drop in caloric intake. Your body senses this drop in incoming energy and adjusts itself to utilize less energy. Similarly, if you use more energy by doing more exercise, your body senses this, too, and responds by increasing your appetite so you will eat more and thus make up the energy deficit. You may also be inclined to rest more and move less in response to an increase in exercise, which, again, serves to conserve energy and maintain homeostasis.

And finally, there is a somewhat mysterious fact regarding the health benefits of exercise that rarely gets any attention and few people even know about. It appears as though regular exercise is not healthy for all individuals. A recent study looking at common health measures of those engaged in regular exercise found that a full 10 percent of test subjects experienced adverse changes in one or more of the following heart disease markers: resting systolic blood pressure, HDL cholesterol, triglycerides, and insulin.