What energy expenditure measurement uses heat released from the subject?

• A. Indirect calorimetry
• B. Bomb calorimetry
• C. Direct calorimetry
• D. Calorimetric spectroscopy

Answer: (C)

Direct calorimetry measures energy expenditure by capturing the heat the body releases during metabolism. This approach relies on the fact that the body's energy production ultimately appears as heat, so measuring the heat flow from the subject gives a direct readout of total energy expenditure. Indirect calorimetry, in contrast, estimates energy use from oxygen consumption and carbon dioxide production, not from heat itself. Bomb calorimetry, meanwhile, assesses the energy content of foods by burning them, not the energy expended by a living subject. Calorimetric spectroscopy isn’t a standard method for this purpose.