What is a Calorie (cal) or Kilocalorie (Kcal)?

So what exactly is a calorie? When we eat things, different types of food supply us with different amounts of calories. We know that butter or oil contains many calories. We also know that a glass of water does not add any at all. So what is the exact definition of a calorie?

Definition

A calorie is the amount of energie that we need to raise the temperature of one gram of water by one degree, at a pressure of one atmosphere.

All these units we use to measure this calorie can seem pretty dry. So imagine boiling water to make some tea. Underneath your kettle, you have a heat source. This heat source will make sure you will not be drinking cold tea.

It is also giving off energy in the form of heat. (In the picture you can see that where the colour is really light, more yellow, the temperature is really high. Where the colour is orange, the temperature is a bit lower.) As you know from putting a kettle of water on the stove and turning the stove on, after a while your water will heat up just like your kettle. The energy (the heat of the fire) is changing the temperature of the water.

This energy can also be expressed in calories. This does not change the amount of energie. You can tell someone how much you weight in for instance kilograms but also in pounds. Or you can tell them how tall you are in centimetres in stead of inches. You do not suddenly loose weight or grow, you just change the way of explaining to someone how heavy or tall you are.

When we are eating food, we supply our body with energy in a food package.If we eat more, take in more energy, than we use and need, our bodies will store that energy. The way our body stores this energy is in the shape of fat. And when our body needs to stay warm, move or do other important things, we use the energy that food supplies us with. The amount of energy we get from the food we eat, is expressed in calories.

Calorie (cal) or KiloCalorie (kcal)?

A calorie is often used interchangeably with a kilocalorie. There is a difference between a calorie (cal) and a kilocalorie (kcal) however.

A kilocalorie (like the name suggests) is the amount of energie that is needed to raise the temperature of one KILOgram of water by one degree at a pressure of one atmosphere. This means that in one kcal, you can find 1000 regular calories.

When we talk about food and calories, you often read amounts like; 230 calories per serving. And this is where it gets confusing. When we talk about food, we say 230 calories, when we are actually talking about kilocalories. Our bodies need more than 230 actual calories per serving!