The basic unit for measuring energy is the scientist’s calorie. This is the amount of energy needed to raise the temperature of one cubic centimetre of water by 1°centigrade. When talking about food and human energy, the measurement most commonly used is the kilocalorie – 1000 times greater – often written as kcal or calorie. Kilojoule (kJ) is the international unit of energy. Approximately 4200 joules or 4.2 kilojoules is equal to one kilocalorie.
Science Behind Calories and Nutrition Facts Labels | BytesizeScience | 12 Dec 2012 | 6m11s