What is the Origin of Resting Energy Expenditure?

This is a core concept in clinical nutrition and thermophysiology, typically quantified through indirect calorimetry measurements in a thermoneutral environment. The 'resting' designation explicitly separates this energy expenditure from energy used during physical activity or the thermic effect of food.

What is the Mechanism of Resting Energy Expenditure?

Resting expenditure is primarily driven by the basal metabolic activity of major organ systems, notably the liver, brain, and the mass of metabolically active skeletal muscle, even at rest. Thyroid hormones exert a profound regulatory influence on the efficiency and rate of mitochondrial ATP production that dictates this baseline energy burn rate. Adrenal health also contributes by maintaining cellular membrane potential and essential ion transport processes necessary for cellular function.

Resting Energy Expenditure

Meaning

The total amount of energy, quantified in calories, that an individual expends daily while in a state of complete rest to maintain fundamental physiological functions, including respiration, circulation, and basic cellular maintenance activities. This value serves as a key determinant of the basal metabolic rate (BMR). It reflects the irreducible energy cost of being alive.