What are the three parts of the energy expenditure equation?

The energy expenditure equation is fundamentally governed by three main components: basal metabolic rate (BMR), physical activity, and the thermic effect of food (TEF).

Basal metabolic rate refers to the amount of energy expended while at rest, which is essential for maintaining vital physiological functions such as breathing, circulation, and cellular production. It represents the largest portion of total energy expenditure for most individuals.

Physical activity encompasses all forms of movement, from structured exercise to daily tasks, contributing significantly to overall energy expenditure. The amount of energy burned through physical activities varies widely among individuals and is influenced by factors such as intensity and duration of the activity.

The thermic effect of food accounts for the energy required to digest, absorb, and metabolize nutrients from the food we consume. While this component represents a smaller fraction of total energy expenditure compared to BMR and physical activity, it can still influence overall energy balance, especially in the context of varying dietary compositions.

These three components together form the basis of energy expenditure calculations, which are essential for understanding metabolism and energy balance in the context of diet and exercise.