By Mark Faries, PhD

Howdy, I am Dr. Mark Faries and we are here separating lifestyle medicine fact from fiction.

We have an obsession with calories. We fear them, yet crave them. We want to watch them, count them, track them, calculate them, avoid them, and even believe that we can somehow burn them. So is the idea of burning calories fact or fiction?

Energy is needed to make the body work, but we cannot directly measure this energy in the body. However, we can attempt to measure the heat that is released when energy is used, and calories help us with this puzzle.

A calorie is a measure of heat energy. More specifically, a calorie is the approximate amount of heat (or energy) necessary to raise the temperature of 1 kilogram, or 2.2 pounds of water, by one degree Celsius.

To know how much energy is stored in a food, we place it in what’s called a “bomb calorimeter,” and then we ignite it to see if we can determine how much heat it gives off. We can then see if this heat is enough to raise our kilogram of water 1º Celsius, and then we convert this heat into units called “kilocalories,” or what we know as calories. Of course our stomachs are not bomb calorimeters. And we do not ignite food as part of our energy use system even though certain unhealthy meals might make us feel this way.

Thereforewe do not burn calories. It would be like saying we burn other units of heat or energy, such as Celsiuses, or Fahrenheits, or even kilowatts.

I guess I can see where the idea comes from though, as calories deal with heat energy stored or released. But, we do not burn them. So the claim that we burn calories is fiction.

Any textbook on physiology, biology or metabolism

Mark D. Faries, PhD

Mark has a PhD in Behavioral Health and an MS in Exercise Physiology. He is an Associate Professor and State Extension Health Specialist with Texas A&M AgriLife Extension and has developed lifestyle medicine curriculum and advocacy. He has served on the Board of Directors of the American College of Lifestyle Medicine, is founder of Lone Star Lifestyle Medicine for Texas and is founder of

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