Thermal Efficiency

Have you wondered how efficient your body is? I don’t mean at walking up and down or lying down. Instead, I refer here to the most basic of human functions. Functioning! The ability to take in energy in the form of calories and convert these calories into energy to exist. A large part of this energy goes into operating the various organs in your body. How efficient is your body in doing this and how is this even measured?

Between the quantity of food, it takes in and the energy it produces, the human body has to be effective. Imagine if you had to eat your body weight in food terms just to remain alive. You would practically be eating all day long. Now I know there are some out there who do that anyways, but that is a story for another day. For the rest of us, we get by being relatively frugal. On average your body needs about twelve calories per hour to function. This energy need is when you are in a state of rest. For humans, this is also measured in Metabolic Equivalent Task or MET. A MET is simply the energy cost of any physical activity. One MET is the energy equivalent of an individual at rest per minute. The standard definition of a MET is 3.5 ml O2·kg−1·min−1.

Rest? You say you are the fitness enthusiast personified? Well, your body only functions at 20 % efficiency. Before you fret, cars in the 1970’s were at 15%, and it is only now that they are getting into the twenties. At converting thermal energy that is. At this level of efficiency, the human body could cycle 290 miles per gallon of food. That is a lot better than most cars out there today. Nature has done an excellent job shaping us. The auto industry is still playing catch-up.


Ritesh is a born again health enthusiast and holds a Certificate in Physiology from Harvard Medical School and a Certificate in Nutrition from Tufts University.