Energy: Expenditure, Intake, Lack of

Definition

Energy expenditure refers to the amount of energy an individual uses to maintain essential body functions (respiration, circulation, digestion) and as a result of physical activity. Total daily energy expenditure is determined by resting or basal metabolic rate (BMR), food-induced thermogenesis, and energy expended as a result of physical activity.

BMR is the minimum amount of energy that the body requires for essential organ and cellular function when lying in a state of physiological and mental rest. BMR accounts for typically 65–75% of total energy expenditure. Differences in BMR exist between genders and across ages. Females tend to have a lower BMR than males, and BMR decreases with age. These differences can largely be accounted for by differences in fat-free mass, which is proportional to BMR.

Food-induced thermogenesis refers to the increase in energy expenditure following the ingestion of food. This increase in energy expenditure is a result of digestion,...