Calories and Kilojoules -Why You Need Them

Calories and Kilojoules -Why You Need Them

It can get really confusing when people say calories, but in New Zealand and Australia, we say kilojoules.

Quite simply, these are measurements of food energy levels. They are both one and the same.

The Low-Down on Food Energy:

The energy food provides is used by our bodies to achieve all levels of activity. From the extreme of running a marathon, down to the simple act of breathing.

To clarify, calories and kilojoules are NOT vitamins or minerals; they have no nutritional value. They DO however, play a significant role in providing your daily energy requirements.

Just like a car, you need fuel.


The human body requires multiple sources of “fuel” which come from the food we eat. Macronutrients are our main sources of energy, these are:

  • Proteins
  • Fats
  • Carbohydrates

All of these can be found in the foods and drinks we consume on a daily basis.

How does it Work?

Your body uses energy that has been consumed and stored.

Without the correct energy source, it will first use up your fat reserves. Then, it will look to your muscles to get protein and use that as an energy source.

This is particularly bad news for bodybuilders, and anyone who is fitness conscious. This is why they drink protein shakes and eat up to 6 small nutrient dense portions of food per day.

Energy Density

The energy density of foods vary according to the different types of macronutrients.

The higher the kilojoules or calories the more energy dense a food is.

  • Protein contains 17 kJ per gram or 4 calories per gram
  • Carbohydrates contain 17 kJ per gram or 4 calories per gram
  • Fat contains 37 kJ per gram  or 9 calories per gram

At first glance, if you wanted more energy, you’d just go for high fat foods right?

Unfortunately, there’s more to it than that.

Please keep in mind, that to maintain a healthy body weight, you need to consume the correct amount of kilojoules or calories to meet your activity requirements. Consuming higher levels than necessary, results in the body storing it as fat.

The source of the energy is an important consideration to make. You do not want the majority of your food energy coming from unhealthy fats or processed sugars, but that in itself is another topic.

Putting it into Practice

Let’s say you want to take an 8 hour hike around the beautiful Waitakere Ranges, or tackle a big day at work.

What could you bring?

  • A carrot?
  • Trail Mix?
  • A peanut bar?

In this case, the trail mix and peanut bar provide the highest energy levels.

A carrot is great, and yes it is healthy, but it has a low energy density, resulting in you burning up that energy too quickly. To obtain the energy levels needed, you would need to buy a whole bag of carrots.

To calculate the energy density of a food is simple. All the information you need is on your Nutritional Information Panel.

It looks like this:


From the above you can see that a 50g peanut bar contains 1184 kj.

The breakdown of this is:

Protein: 8.3g = 141 KJ

Carbohydrates: 21.6g = 367 KJ

Fat: 18.3g = 677 KJ

4.2 Kilojoules equals 1 Calorie; so one 50g bar contains a total of 161.21 calories.

A hike or very busy day may take up approximately 7532 KJ or 1800 calories of energy.

That is A LOT of energy needed so pack in that peanut bar and trail mix.

How Much Energy Do You Need?

If you’re living an inactive life, or are slightly more senior than the rest, you probably don’t need as much energy as someone who is physically active or a young teenager.

Everyone is different, one great way to calculate your energy requirements is to use an online calculator. This takes in to account many factors including your age, activity level, goals and sometimes your height.

Don’t forget to trust your body. It is necessary to make these health related decisions based on your intuition. Understand that nutrient dense foods with naturally occurring energy levels, are your best bet to living a healthier balanced life.

Our Shameless Promotional Piece!

With all this talk about food energy, how do Health Discovery products stack up?

Nutrients and energy come from the right food. 

Being tired or listless often comes down to the food you eat.

Our range is naturally energy dense, and is great for supporting your daily lifestyle. Some of you want more than just a sugary treat.

At Health Discovery, we take great care to balance the all-natural nutrient and energy rich ingredients in the products we hand craft.

Good health, and a vibrant lifestyle need looking after.

We help you choose wisely.

Written by Bianca Don

Leave a comment