What is the Difference Between Calories and Kilojoules?

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Calories and kilojoules are both units of energy that represent the same thing: the amount of energy in foods and drinks we consume. The difference between them is that calories are part of the imperial system, while kilojoules are part of the metric system. In other words, they are just two different ways of measuring the same thing, like miles and kilometers.

Here are some key points about calories and kilojoules:

  • One calorie (kcal) is equal to 4.18 kilojoules (kJ).
  • To convert calories to kilojoules, multiply the calories by 4.18. To convert kilojoules to calories, divide the kilojoules by 4.18.
  • In the United States, calories are more commonly used, while kilojoules are more widely used in Australia and other countries that use the metric system.
  • The terms "calories" and "kilojoules" may be used interchangeably, but it is essential to know the difference when comparing or converting values.

Regardless of the term you use, the main focus should be on how calories or kilojoules relate to achieving and maintaining a healthy weight. Both are measures of energy, and consuming more energy than you expend can lead to weight gain, while consuming fewer calories or kilojoules than you burn can result in weight loss.

Comparative Table: Calories vs Kilojoules

Here is a table comparing the difference between calories and kilojoules:

Aspect Calories Kilojoules
Unit of Measure A unit of energy used to measure the energy content of food and drinks Equivalent to calories, but the scale is different; same purpose as calories
Abbreviation Cal kJ
Conversion 1 Calorie = 4.184 Kilojoules
1 Kilojoule = 0.2 Calories
1 Calorie = 4.2 Kilojoules
1 Kilojoule = 0.239 Calories
Usage Calories were used as the unit of measurement for energy in food until Australia officially stopped using the term in 1988 Kilojoules are used as the unit of measurement for energy in food in Australia since 1988
Energy Sources The energy content of foods depends on the amount of carbohydrates, fats, and proteins present in the food, and the portion size Food energy used to be measured in Calories (Cal), but now it is measured in kilojoules (kJ) in Australia

In summary, calories and kilojoules are both units of measurement used to quantify the energy content of food and drinks. They are essentially the same thing, but the scale is different, with kilojoules being the metric system equivalent to calories in the imperial system. Calories were used in Australia until 1988, when the country officially switched to using kilojoules as the unit of measurement for energy in food.