It's a fairly simple rule to follow if you're looking to lose weight: If you eat more kilojoules than you burn, you'll gain weight; if you eat fewer kilojoules than you use, you'll lose weight.
According to registered dietitian Wesley Delbridge, a spokesman for the Academy of Nutrition & Dietetics, the number of kilojoules you need to lose, gain or maintain weight depends on your activity levels, body size, hormones and even sleep.
But, what is a kilojoule? The short answer is: It's a measure or unit of energy. If you say that a certain amount of a specific food contains 420kJ, for example, it means that if your body completely metabolises the food, 420 metric units of energy are released. Your body needs this energy for physical activity, digestion and breathing.
We took a look into what a kilojoule is, where kilojoules come from and how you can burn more of them.