Let's Talk Calories!

This article is a summary of what a 'calorie' is, as well as how calories work within our body. Most of us hear or see the word 'calorie' every day, whether we go looking for it or not. On social media, news segments, magazine articles; all talking about calories and how many we should consume, through what foods, at different times of day.. usually without telling us what a calorie is or does. Once we've learnt the basics, it makes processing all this information much easier and will hopefully encourage you to learn more about your body's energy consumption and expenditure.

General Definition of a Calorie

A calorie itself isn't something you can see or hold in your hand, it's a unit of measurement. Calories are used to measure the amount of energy in the food and beverages that we consume. This energy is needed to keep our body functioning and alive. Every day we rely on the energy that comes in the form of calories. Regardless of what food we consume, whether it be healthy or unhealthy, it all provides calories. However, within the calories we consume it is important that we take on foods that contain quality nutrients to keep the body healthy. Macro and micro nutrients won't be covered in this article, but within your calories it's vital to have a healthy balance.

Scientific Definition of a Calorie

Let's get a little bit science-y for a second, hang with me.. A calorie is a unit of measurement used in nutrition to measure the consumption and expenditure of energy within our bodies. A calorie, as most know it, is actually a kilocalorie (1000 small calories). A small calorie (cal) is the amount of energy required to increase the temperature of 1 gram of water by 1 degree celsius. Therefore, a kilocalorie (kcal) is the amount of energy required to increase the temperature of 1 kilogram of water by 1 degree celsius. This relates to the amount of energy required from the body to burn certain amounts of different foods.

In the this article we're going to refer to kilocalories as just calories, as they're more commonly known.

1 kcal = 1000 cal

Calories vs Kilojoules

Although this post will discuss calories, be aware that in Australia we measure nutrient energy with the unit kilojoules or 'kJ' as you'd read it on the nutrition labels. Even though this is the case, most times where nutritional energy is being discussed calories will be the unit of measurement in conversation.

Essentially, the difference between calories and kilojoules is terminology and you can convert calories to kilojoules by multiplying the calories by 4.2. Calories seem to have stuck around thanks to its use in America, even amongst Australians, which is why I've chosen to discuss calories over kilojoules.

1 kcal = 4.2 kJ

Consumption vs Expenditure Consumption vs Expenditure of calories is the equation that essentially determines whether body mass increases, decreases or stays the same. An increase in body mass occurs when consumption is higher than expenditure (calorie surplus). A decrease in body mass occurs when consumption is lower than expenditure (calorie deficit). Equal consumption and expenditure will see the body maintain its current mass.

As we've already mentioned, all foods that we consume contain calories that our body will use as fuel. Putting hand to mouth with food and drink is the only way calories enter our body, giving you full control (theoretically) over your calorie consumption. However, there are many ways in which our body expends the calories we consume and even without moving we require energy at rest. Here are the 4 main ways our bodies expends energy throughout the day: The total of all these combined is called out Total Daily Energy Expenditure (TDEE).

  • Resting Metabolic Rate (RMR) - Calories burnt at rest

  • Thermic Effect on Food (TEF) - Calories burnt through chewing/digestion etc

  • Non-Exercise Activity Thermogenesis (NEAT) - Calories burnt through everyday activities

  • Purposeful Exercise - Calories burnt through exercise

Balance Equation

Although counting or tracking calorie consumption seems to be something only the 'crazy fit people' do, It pays to understand how the balance of consuming and expending calories affects our body. Learning how many calories are actually in the foods you consume and how many calories you burn day to day can be done with relative ease. Once armed with this knowledge, the mysteries of weight loss and weight gain in the human body become not so mysterious.

How many Calories should I eat?

The amount of calories we should or shouldn't eat comes down to factors like age, size, lifestyle and goals. There are guidelines out there that give you a ball-park figure based on average statistics. It's worth diving in and working out a consumption requirement that's more personal to you and what you're looking for. To do this you would first need to find your Total Daily Energy Expenditure (TDEE) and from there work out your calorie requirements i.e surplus, deficit or maintenance depending on your goals. Do further research or consult a professional to ensure your calorie surplus or deficit is sufficient without being too significant as either can have negative effects. Ensure your macro and micro nutrients are considered for a healthier, more balanced nutrition plan.


Having knowledge of how energy balance occurs in the body as well as the caloric content of the food you eat and the amount of calories your body expends day to day will give you more control over your own body than you once thought possible. You'll also come to learn that while exercise has many healthy benefits, it is not the final factor when it comes to weight loss. I hope this article spurs you to research further and take more control of your day-to-day eating and movement habits.

Get in contact with a professional and make the investment, lifelong knowledge is priceless.

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