Foods and drinks supply the body with energy (calories) and nutrients (macronutrients and micronutrients) as well as dietary fibre and water.
Energy
Energy is needed by the body to stay alive, grow, keep warm and be active and is provided by food and drink. Different people need different amounts of energy in their diet, because body size, age, gender and level of physical activity will vary from one person to another.
Energy is measured in calories or joules.
A calorie is defined as the energy needed to raise the temperature of 1 gram of water from 14.5 to 15.5°C.
1 Calorie = 1,000 calories and is commonly refered to as kilocalorie (kcal).
A joule (J) can be defined as the energy used when 1 kilogram (kg) is moved 1 metre by the force of 1 Newton.
1 kilojoule (kJ) = 1,000 joules.
1 kcal = 4.184 kJ
The Calorie has been adopted as the unit of energy in nutrition, and so is often referred to on packaging.
