Nutrition Science and Everyday Application - beta v 0.1

374 ALICE CALLAHAN, PHD, HEATHER LEONARD, MED, RDN, AND TAMBERLY POWELL, MS, RDN
Figure 7.3. Components of total energy expenditure include basal metabolism, the thermic effect
of food, and physical activity.
1. Basal Metabolic Rate (BMR)
BMR is the energy expended by the body when at rest. These are the behind-the-scenes
activities that are required to sustain life. Examples include:
• respiration
• circulation
• nervous system activity
• protein synthesis
• temperature regulation
Basal metabolic rate does not include the energy required for digestion or physical activity.
If a person is sedentary or moderately active, BMR is the largest component of energy
expenditure, making up about 60 to 75 percent of total energy output. For example, a
sedentary person might need about 1800 calories in a day, with about 1200 of them being
for BMR.