What method can be used to measure metabolic rate indirectly?

Measuring metabolic rate indirectly can be effectively done through spirometry, which assesses respiratory gases. This method measures the volume of air inhaled and exhaled by the lungs and analyzes the concentration of oxygen and carbon dioxide in the breath. By understanding the exchange of gases during respiration, one can estimate the metabolic rate because oxygen is consumed by the body to produce energy and carbon dioxide is produced as a waste product.

Calorimetry, while known for its ability to measure metabolic rates directly through heat production, is not the method indicated in this context for indirect measurement. Options that involve glucose uptake testing and body mass index calculation are also not methods used for measuring metabolic rate indirectly. Glucose uptake testing provides information about glucose metabolism rather than overall energy expenditure, while body mass index is a simple calculation that does not assess metabolic rate at all. Therefore, spirometry stands out as the most relevant method for indirectly measuring metabolic rate through gas exchange analysis.