Human Resting Energy Expenditure Varies with Circadian Phase

Fasted resting energy expenditure varies by circadian phase, with lowest levels at approximately 0° and highest levels at approximately 180°.

• Circadian misalignment may influence energy expenditure and obesity risk in individuals with irregular schedules.
• The study demonstrates that resting energy expenditure (REE) varies independently of sleep and activity patterns.
• Respiratory quotient (RQ), indicating how the body uses macronutrients, also fluctuates with circadian phase.
• Lowest RQ values occur around circadian phase 240°, while highest values are observed at phase 60°, correlating with biological morning.
• Findings suggest that variations in energy expenditure and macronutrient metabolism could be linked to weight gain in shift workers.

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