A macrocalorie is another name for a kilocalorie, 1 kcal = 1 macrocalorie = 4,184 joules = 4.184 kilojoules, so 1,000 kilojoules equals 239 kilocalories. A kilojoule is a unit of heat and refers to one thousand joules. Kilojoules are now commonly used to measure the number of calories contained in food, as well as the number of calories burned in a given unit of exercise. People generally control their weight by controlling the number of calories consumed in food and the number of calories burned in exercise. All calorie units are interconvertible. By counting calories, people can control their intake and maintain good control over their weight. For some people who need to lose weight, they need to know the conversion between these units in order to do a good job of losing weight.