If you've ever tried to lose weight, you've probably heard of calorie counting. But is it really a simple case of calories in, calories out?

“Calories in, calories out” is a phrase commonly heard in health and fitness circles. But what does it actually mean?

Here’s the lowdown on calories and how to calculate your energy requirements to support your fitness goals.

You'll find in this article:

What is a “calorie”?

The technical definition of a calorie is the energy required to raise the temperature of 1 gram of water by 1 degree Celsius.

But to most people, calories represent the energy that a food or drink provides. All bodily processes, from breathing and thinking to digesting food, require energy. Calories are the unit we use to quantify this energy.