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Energy or kilojoules

Consuming energy from foods and drinks is essential as our bodies need energy to maintain basic bodily functions. Understanding which products are energy-dense can help you balance the energy you consume with the energy your body burns, which is often referred to as an ‘energy in – energy out’ balance. This may be helpful if you’re looking to lose or maintain weight.

What is energy?

In Australia, energy in food and drink is measured in kilojoules while other countries may use calories or kilocalories. The basic relationship is 1 calorie (Cal) = 4.2 kilojoules (kJ). The average recommended daily energy intake of an Australian adult is 8,700kJ.

It is important to be ‘kilojoule aware’ (but not count kilojoules), which means having an awareness of the types of food that provide the most kilojoules, to avoid consuming more kilojoules than your body actually needs each day. The main sources of energy (or kilojoules) from food and drink are protein, carbohydrates, fat and to a lesser degree, alcohol. These are also called ‘macronutrients’.

Why do our bodies need energy?

Our bodies need energy to function. This includes our most basic bodily functions like breathing, keeping the heart beating, maintaining body temperature, growth and development of new tissues, and digesting food and drink consumed.

The second largest user of energy is physical activity, which can vary depending on what you’re doing each day.

What are the recommendations for energy intake?

The amount of energy (or kilojoules) required for a person varies with age, gender, body size or composition and activity. Additional energy is required in pregnancy and lactation, and during growth and development (children and teenagers).

Estimated energy requirements for adults are calculated using basal metabolic rate (BMR) x physical activity level (PAL). To maintain a healthy weight, we need to balance the energy (or kilojoules) consumed with the amount of energy the body requires. To calculate your individual daily energy needs, use our quick and easy kilojoule calculator.

Recommendations on the total energy intake from the key macronutrients (fat, carbohydrate and protein) have been developed in relation to a reduced risk of chronic disease. These recommendations are called the Estimated Acceptable Macronutrient Distribution Ranges and are: 20-35% total energy intake from fat; 45-65% from carbohydrate; and 15-25% from protein. Outside these ranges, the risk of chronic disease, overweight and obesity, and inadequate micronutrient intake (vitamins and minerals) may increase.

What happens if we consume too much or too little energy?

If too much energy is consumed compared to what is required, body weight is more likely to increase as excess energy is likely to be stored as body fat. If the energy consumed is less than the body requires, weight loss is likely to occur.