Resting energy expenditure and substrate oxidation do not differ between night and day shift workers: A real-life...

Area of Science:

• Metabolic Health
• Occupational Health
• Chronobiology

Background:

• Shift work is prevalent and associated with metabolic disturbances.
• Understanding the metabolic impact of night shift work is crucial for public health.
• Previous studies suggest altered energy expenditure and substrate utilization in shift workers.

Purpose of the Study:

• To investigate differences in resting energy expenditure (REE), respiratory quotient (RQ), and substrate utilization between night and day shift workers.
• To assess the impact of shift work timing on metabolic parameters.
• To identify potential metabolic consequences of circadian disruption due to shift work.

Main Methods:

• Cross-sectional study of 62 male workers (30 night shift, 32 day shift).
• Indirect calorimetry used to measure REE, RQ, and carbohydrate/fat oxidation.
• Linear regression and Generalized Estimating Equations (GEE) applied, adjusting for age, workload, and other confounders.

Main Results:

• Initially, night shift workers showed lower RQ and carbohydrate oxidation, and higher fat oxidation (adjusted for age).
• However, after adjusting for workload, no significant differences in REE, RQ, or substrate oxidation rates were found between night and day shift workers.
• Specific values for REE, RQ, carbohydrate, and fat oxidation showed no statistically significant divergence between the two groups.

Conclusions:

• Night shift work does not appear to differ from day shift work in terms of resting energy expenditure and substrate oxidation when workload is considered.
• The findings suggest that factors beyond shift timing, such as workload, may play a significant role in metabolic outcomes.
• Further longitudinal studies with larger sample sizes are recommended to validate these results and explore other influencing factors.