Final answer:
Indirect calorimetry calculates the metabolic rate by measuring oxygen consumption, based on the understanding that energy production is directly related to oxygen utilization, with 4.8 Kcal of heat liberated per litre of oxygen. It is an alternative to direct calorimetry methods like bomb calorimetry, and is commonly used in research to measure energy expenditures in various scenarios.
Step-by-step explanation:
Indirect calorimetry is a method used to calculate the metabolic rate of an individual by measuring the amount of oxygen consumption. It is based on the principle that the utilization of oxygen in the oxidation of organic nutrients is directly proportional to the energy produced, with approximately 4.8 Kcal of heat liberated for every litre of oxygen used. This technique estimates metabolic rate by using devices such as the Benedict-Roth spirometer, which accurately measures the rate of oxygen consumption at rest or during very light exercise.
Unlike direct calorimetry, such as the bomb calorimeter method, which measures the heat produced when a food sample is completely burnt in oxygen, indirect calorimetry does not measure heat output directly. Instead, it relies on oxygen consumption as an indicator of energy expenditure. The method is predominantly used in research settings, and to develop nutritional and exercise recommendations based on a person's energy expenditures, as seen in studies like those undertaken by Carla Prado's team at the University of Alberta.