What’s A Calorie?

Sometimes, after living something for years, you forget that you once were a beginner who knew virtually nothing. That happened to me yesterday when I saw an email from a reader. The email had a very basic question in it which was “what is this thing we call a calorie?” My first thought was, “oh wow, how could anyone not know this.” Then I remembered that not too long ago, I didn’t know this myself. So my apologies to the sender of this email and my thanks to her for allowing me to post the response.

What Is A Calorie?

A calorie is a unit of measurement, like a yard, meter, gram or gallon. More specifically, it’s a unit of measurement for energy. So if yards and meters measure length and gallons measure volume, a calorie measures energy. Even more specific, a calorie is the amount of energy required to heat 1g of water by one degree celsius. By the way, that’s a very broad definition right there, since the amount of energy required to heat up water varies by air pressure, water purity and a few other factors. However, for our purposes, stating that a calorie is the amount of energy required to heat up one gram of water by one degree celsius is close enough.

Wow, I Must Be Burning Thousands Of Calories Just Standing Here!

When I first learned this I did a quick calculation in my head. Let’s see, I weight about 100 kilo grams which is about 100,000 grams. My body temperature is about 37 degrees Celsius. So if I just stand outside on a cold day I’d be burning thousands of calories an hour as my body raced to keep me warm, right? Yah, not so much. Unfortunately, in an attempt to confuse you even more, a calorie used for food is actually 1,000 of the original calories. So a food calorie is actually the amount of energy required to heat up 1 kilo gram of water by 1 degree Celsius. For your non metric folks out there, that means a food calorie is the amount of energy required to heat up 2.2lbs by about 1.8 degrees Fahrenheit.

So now when I look at the energy requirements to keep my body warm, they don’t sound so high. They’re measured in the 100’s and not in the 1000’s. Plus my body doesn’t lose enery very quickly since I don’t typically go outdoors on a cold day wearing no clothes, which also reduces the energy requirements.

By the way, our bodies don’t use calories just to keep warm, that’s just one way in which this energy could be used. For example, moving a part of the body also uses up energy, which can be measured in calories. That’s why a lot of gym equipment can show you how many calories you’ve used up in your current workout. It’s basically figuring out how much energy you’ve spent and then translating it into this standard unit of measurement.

So How Do We Get Calories From Food?

So if the previous section explained how we used calories, then how the heck do we get calories out of food? Well, that’s a more complicated explanation involving a lot of chemistry and biology. I’m sure that some scientist out there is going to cry when he reads my amazingly simplified explanation but hey, I’m not trying to teach biology here. Essentially, the bottom of the food chain are plants, who take energy that they absorb from the sun and store it as chains of carbon molecules. As animals eat plants and we eat both plants and animals, these carbon chains are broken down to release the energy stored there by the plant. If we can’t use the energy right away, we store the energy in various forms, one of them being fat and another being various sugars. That’s why foods that contain sugars and fats are so high in calories, because we’re basically eating something else’s energy storage.

It’s Good To Know What A Calorie Is

By understand calories and what they represent, a lot of things about fitness and health make more sense. For example:

Now it makes sense why turning the thermostat down a bit in our homes would help us burn more calories. The room temprature is lower which means our bodies have to spend more calories trying to keep us warm.
Negative calorie foods also make sense. It’s not that these foods somehow grab calories and go hide them somewhere. Negative energy foods like celery still have some calories in them, it’s just that the energy required to chew and digest them is more than the energy we get out of them.

You can even use this knowledge to understand a few more things about your body. For example:

Why do we sweat? Well, because your body is trying to keep cool. So it puts out moisture. The body then uses up extra heat energy to evaporate this moisture, causing your to be cooler. (and yes, that’s a very simplified explanation of perspiration).

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Fitness is part art and part science. The science part tells us the basic facts. The art part is how we apply those facts to our daily routines. The art is important, but it’s also important to educate yourself about the science underlying all this art.

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