ABSTRACT
This chapter describes methods of measuring metabolic rate and energy balance. The basal metabolic rate (BMR) is the energy expended for the on-going processes in the body in the resting state, when no food is digested and no energy is needed for temperature regulation. The measurement of BMR on subjects drawn from a variety of populations provides a basis for studying the relationships between metabolic rate and body size, sex, and age. Since the time of Galileo Galilei scientists have believed that BMR and resting metabolic rate are related to body surface area. If the BMR values are expressed per unit of lean body mass then the sex differences are essentially eliminated. Differences in body composition also largely explain the 2% decrease in BMR per decade observed through adulthood. The chapter discusses methods of measuring energy expenditure using expired air analysis. It provides an examples of the measurement of metabolic rate and energy balance.
