Calories and the Electric Car

By: Leo Desforges

The word “calorie” is an unnecessarily confusing way of saying “energy.” A calorie is just a way of measuring the energy value stored in food. Just like we measure electricity in kilowatt hours or gasoline in gallons, calories are merely a way of measuring energy. In fact, most countries in the world that label their food do not use the term calories. They actually use the term “energy” on food labels instead. Makes sense, right? Unfortunately, much like we Americans have not adopted the metric system, we still choose to use the word “calorie” instead of “energy,” further confusing folks on the whole nutrition thing.

Hopefully this next analogy will be helpful in further understanding how the human body processes and utilizes energy (calories):

The human body is like an electric car with a backup motor. There are a few electric cars on the market today that can run on battery power alone for about 35 miles (think Chevrolet Volt). After around 35 miles, the battery is depleted, and the car automatically switches over to a gasoline-powered motor (which is similar to any non-electric car). As long as there’s gasoline in the tank, you can keep driving. When you get home, you plug your car back in to recharge the battery, which prepares the car for another 35 miles of gas-free driving. Now this is a mild oversimplification of electric/gas hybrids, but it’s close enough and will help me demonstrate how human metabolism works on a daily basis.

Every time we eat a meal, it’s as if we are charging our batteries a bit. We eat, and our body “runs” on this recently digested fuel. The size of the meal affects how much “charge” we put in our batteries. But even after a Pesach-sized meal, eventually we run out of charge. At this point, our bodies switch over to their alternate fuel source, just like the car. This alternate fuel source is body fat. Once the recently digested food energy has been used, body fat becomes a nearly limitless fuel source for the human body to run on.

Unlike the car, the human body not only has a nearly limitless supply of fuel (body fat) but also a way to convert excess food energy (calories) into stored fuel for later use. The car can only accept so much electricity. It will not magically convert excess electricity into gas for later. The human body can! If we overeat, any energy that we don’t use before our next meal gets stored as fat for later use. Equally, if we run out of energy from a recently digested meal, we smoothly (sometimes hungrily) shift to fat as a fuel source and keep functioning just fine.

This analogy is also an oversimplification but close enough to serve as a primer on human metabolic function. Next month, I’ll delve deeper into this topic. As always, questions, comments and complaints are welcome!


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