Energy can be measured in two types of units: calories and joules. Because the amounts involved in the measurement of energy provided by foodstuffs are so large, kilocalories (1 000 calories) and kilojoules (1 000 joule) are mostly used as units of energy.
A multiplier of 4,2 must be used to convert kilocalories (or just "calories") to kilojoules.
Energy supplied by macronutrients
The number of calories in a food product is an indication of the potential energy the food possesses. The energy value of the macronutrients can be calculated as follows:
- 1 g protein provides 4 calories
- 1 g carbohydrate provides 4 calories (dietary fibre excluded)
- 1 g fat provides 9 calories
All calories are the same