Does indirect calorimetry measure heat released from the subject?

• A. Yes
• B. No
• C. Only with a heat sensor
• D. It measures both heat and gas exchange

Answer: (B)

Indirect calorimetry estimates energy expenditure by measuring respiratory gas exchange—how much oxygen is used and how much carbon dioxide is produced—and then calculates calories burned from those values. It does not directly measure heat released by the body; heat production is inferred from the energy expenditure, not measured with a heat sensor. Because of this, it answers that heat is not measured directly. The device’s role is to quantify gas exchange to derive energy use, not to capture heat output.