According to the Better Health Channel a kilojoule is a unit of energy. It also refers to the energy value of food and the amount of energy our bodies burn. The common term for this used to be ‘calorie’. Fats and alcohol are the most energy-dense foods. Some carbohydrate foods are metabolised faster than others and are known as foods with a high glycaemic index (GI).
Kilojoules and Calories
Looking at a nutrition information panel you might see kJ or calories listed. What do they mean? How much should you be having each day?
What are they?
Put simply kJ’s and Calories measure energy that is found in food and drinks. They are also used to describe how much energy we burn when we move around.
Since they measure the same thing you can convert between the two:
Calories and kJ converter
You can use our converter below to figure out the kJ’s or calories.
An important note
There is a difference between Calories and calories. The Calorie with the big capital C has the same energy value as 4.2 kJ. The calorie with the little c is used in science to measure the amount of energy needed to heat water. This means that there are 1000 calories (note little c) in a big Calorie (note big C). This is confusing! But just remember the capital letters:
Why we need energy
Energy is the fuel for our body, so we need to make sure we get enough from our food and drink. To be healthy and weight stable, making sure that our energy is balanced is the key. This means that what we eat (energy in) equals what we use (energy out). If we consume more energy than we use, this will lead to weight gain. On the other hand if we use more energy than we eat, we will lose weight.
Kilojoules in food
Different foods have different energy values (meaning those fried chips are higher in fat and therefore energy than your veggies for example). The energy value per gram for each of the macronutrients is:
- Fat – 37kJ (9 Cal)
- Alcohol – 29kJ (7 Cal)
- Carbohydrates – 16kJ (4 Cal)
- Protein – 16kJ (4 Cal)
- Water – 0kJ (0 Cal)
So how much energy do we need each day?
This is different for each person; however it is recommended that an average daily intake for Australian adults is 8700kJ (or 2079 Calories). However it is important to remember that this is a guide and some people (pregnant, breastfeeding, kids and athletes) will need more/less energy each day.
If you are unsure of how much energy you should be consuming each day, book an appointment to see our dietitian Rhiannon Welsh at ENT Wellbeing Diet and Nutrition, Sydney – Phone 1300 123 368