What are the four components of energy expenditure? Which is the biggest component?

1. Basal metabolism: minimal amount of energy required to keep a resting, awake body alive in a warm, quiet environment (e.g., energy for heartbeat, breathing, brain function, etc.); accounts for 60% to 75% of total energy expenditure
2. Physical activity: includes activities of daily living and planned exercise; accounts for 15% to 35% of total energy expenditure (highly variable)
3. Thermic effect of food: energy needed to digest, absorb, and metabolize nutrients; accounts for 5% to 10% of total energy expenditure
4. Adaptive thermogenesis: energy spent on nonvoluntary activities that maintain body temperature; accounts for <5% of total energy expenditure (negligible)