Kilojoule Health Dictionary

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Kilojoule: From 1 Different Sources

The unit of energy equal to 1,000 joules, abbreviated to kJ. One kcal (see kilocalorie) equals 4.2 kJ.
Health Source: BMA Medical Dictionary
Author: The British Medical Association

Energy

The capacity to do work or effect a physical change. Nutritionists refer to the fuel content of a food as its energy.

There are many forms of energy, including light, sound, heat, chemical, electrical, and kinetic, and most of them play a role in the body. For instance, the retina converts light energy to electrical nerve impulses, making vision possible. Muscles use chemical energy obtained from food to produce kinetic energy, movement, and heat.

Energy is measured in units called calories and joules.

Because these units are extremely small, more practical units used in dietetics are the kilocalorie (kcal, 1,000 calories), and kilojoule (kJ, 1,000 joules).

Carbohydrates and proteins provide 4 kcal per gramme (g), fats provide 9 kcal per g (see metabolism).

In general, the energy liberated from the breakdown of food is stored as chemical energy in ATP molecules.

The energy in these molecules is then available for processes that consume energy, such as muscle contraction.... energy

Joule

The international unit of energy, work, and heat. Approximately 4,200 joules (symbol J) or 4.2 kilojoules (kJ) equal 1 kilocalorie (kcal); 1 kJ is equal to about 0.24 kcal. (See also calorie.)... joule

Basal Metabolism

the minimum amount of energy expended by the body to maintain vital processes, e.g. respiration, circulation, and digestion. It is expressed in terms of heat production per unit of body surface area per day (basal metabolic rate – BMR), and for an average man the BMR is 1.7 Calories (7.115 kilojoules) per day. BMR may be determined by the direct method, in which the subject is placed in a respiratory chamber and the amount of heat evolved is measured, or (more normally) by the indirect method, based on the *respiratory quotient. Measurements are best taken during a period of least activity, i.e. during sleep and 12–18 hours after a meal, under controlled temperature conditions. Various factors, such as age, sex, and particularly thyroid activity, influence the value of the BMR.... basal metabolism

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