The measurement of the calorie value of foodstuffs or the energy expenditure of a person. In direct calorimetry, a small measure of food is burned up inside a sealed container, which is immersed in water. The rise in water temperature that results is used to calculate the calorie value.
Energy production in humans is measured by oxygen uptake.
Every litre of oxygen taken into the body produces 4.8 kilocalories of energy.
Energy production is calculated by comparing the percentage of oxygen in air inhaled and exhaled.
A unit of energy. One calorie is the amount of energy needed to raise the temperature of 1 gram of water by 1°C. However, the term calorie is also used in medicine and dietetics to mean kilocalorie, a larger unit equal to 1,000 calories. Normally, when calorie intake matches the amount of energy expended, body weight remains constant. If intake exceeds expenditure, weight is usually gained; if expenditure exceeds intake, weight is usually lost. In general, fats contain the most calories. Energy can also be measured in joules: 1 calorie equals 4.2 joules. (See also calorimetry; diet and disease.)... calorie
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