What is a calorie?

They are listed on all food packaging, and many menus. We are told that a “general” diet is 2000 calories per day. Googling “What is a calorie?” will get you some results that talk about diets and tell you that it is a unit of energy. It is the amount of energy to heat some amount of water a few degrees.  Blah blah, not interesting... Back in the 1800s heat of food and other things was measured by burning them. For the steam engine, things that burned hotter, probably made more steam.

So how hot is hot? What does a calorie feel like, or look like? I wanted to show that so I made a YouTube video. It is only 3 minutes long, and it is the first video I made with my face in the picture. It is also unedited and done in one take. I did this because editing videos takes much longer than just recording them. I shared it with my family and friends–and my friends' children. They commented that it was much better to see the person and when I make mistakes it is “more real.”

Before you click, I want to say that a "food" calorie is actually 1000 chemical calories. There is lots of energy in food. A marshmallow is 25000 thermochemical calories. You may notice in Canada, and Europe where they aren't as opposed to the metric system, the nutrition labels say "kcal" and that added k means 1000x.

Now that you have seen it, you can more easily visualize that one marshmallow has enough energy to boil a cup of water. Normally we don't get all of the energy by burning something since we don't have a 100% oxygen atmosphere. Inside our bodies though the miracle of biochemistry can get lots of energy out of food without converting it all to heat (and light.)

You may be wondering how many calories does it take for some activity. 

Getting around on foot (walking or jogging) is roughly 100 calories per mile. So four marshmallows per mile, or one 12oz Miller Lite.

Now cycling is much more efficient so your calories will get you two or three times as far.

Is that a surprise? 

I hope you enjoyed my video.

Sometimes Just searching the internet only gets you numbers that don't necessarily make sense, especially in science. My goal is to put things like this together that don't take too long to read and provide a nice jumping off point for learning the chemistry and math later.