Our bodies need the energy to grow and repair themselves, keep warm and do physical activity. Energy comes from food and drinks, in particular from carbohydratesproteinfat and alcohol. Carbohydrates, protein and fat are essential macronutrients (often called ‘macros’) as we need them in our diet in large amounts (macro=large) to survive and function. Alcohol is non-essential (not needed in our diet).

Energy is measured in kilojoules (kJ) or calories (kcal).

1 kcal = 4.2 kJ

Kilocalories are commonly called ‘calories’. For example, you’ve probably heard someone say ‘this ‘food is 100 calories’ but the technically accurate statement would actually be ‘this food is 100 kilocalories’.

Energy values of different nutrients

NutrientEnergy provided
Carbohydrate17 kJ (4 kcal) per gram
Protein 17 kJ (4 kcal) per gram
Fat37 kJ (9 kcal) per gram
Alcohol29 kJ (7 kcal) per gram

As you can see, fat contains more than twice as much energy as carbohydrates and protein, closely followed by alcohol. This needs to be taken into account when we are watching our weight, or trying to reduce it.

Energy density

Food and drinks are made up of different amounts of protein, fat, and carbohydrate (and sometimes alcohol); The amount of each in the food or dirnk will determine its energy content.

Foods that are high in kilojoules per bite, tend to be high in fat and/or sugar (for example, chocolate, fizzy drinks, fats and oils). Such foods are described as energy-dense.
Low energy-dense foods (for example fresh fruit, vegetables and porridge) have fewer kilojoules in each bite.

But remember it is not only the type of food that we eat but how much – a large plate will have more energy (kilojoules) than a smaller portion. 

How much energy do I need?

How much energy you need is dependent on your gender, age, weight, and how active you are. You can use the Nutrient Reference Value’s online tool to estimate your recommended daily energy requirements. If you are particularly active or play sport, visit our sports nutrition page for information on meeting your energy needs.

Typically men require more energy than women, and we tend to need less energy as we age due to a decrease in muscle mass. Teenagers have large energy needs to cater for all the growing they are doing.

How much of each macronutrient do I need?

The Acceptable Macronutrient Distribution Range (AMDR) tells us what percentage of our energy should come from each macronutrient (carbohydrates, fat and protein).

  • Carbohydrate: 45-65% of total energy
  • Fat: 20-35% of total energy
  • Protein: 15-25% % of total energy

Source: Nutrient Reference Value: Summary


To maintain a healthy body weight, we should only consume as much energy as we need. Unused energy is stored as fat which accumulates over time, causing weight gain.

If you would like more information on your energy intake or energy requirements, contact a dietitian/nutritionist who can assess your needs and advise you accordingly.


National Health and Medical Research Council (Australia) and Ministry of Health (New Zealand) (2017). Nutrient Reference Values for Australia and New Zealand: Summary


Last reviewed: 20/06/2022  

Last modified: June 20, 2022