Impacts of lifestyle behavior and shift work on visceral fat accumulation and the presence of atherosclerosis in middle-aged male workers.

Work style, and particularly shift work, can affect an individual's circadian rhythms. Moreover, lifestyle habits, including dietary and exercise routines, might be altered by irregular shift hours. The present study investigated how lifestyle and shift work affect the accumulation of visceral fat and the presence of atherosclerosis in middle-aged male workers. This study enrolled employees undergoing their periodic health check-up (n = 10,073). Visceral fat area (VFA) was evaluated by computed tomography. Atherosclerosis was assessed by the cardio-ankle vascular index (CAVI), carotid intima-media thickness (IMT), and carotid plaque. Lifestyle was evaluated by the following items: (1) eating breakfast, (2) nighttime eating, (3) regular exercise, (4) habitual drinking, (5) habitual smoking, (6) sleeping hours, and (7) working hours. Shift workers were defined as employees who were not engaged in fixed daytime work. The VFA and CAVI were significantly greater in fixed daytime workers than in shift workers, while the carotid IMT was lower in fixed daytime workers than in shift workers. Reduced regular exercise and fixed daytime work were independently associated with visceral fat accumulation by both multivariate regression and logistic regression analyses. Habitual smoking was independently associated with an increased CAVI and carotid atherosclerosis in both multivariate regression and logistic regression analyses. Reduced regular exercise and fixed daytime work were significantly associated with visceral fat accumulation, while habitual smoking had a consistent association with the presence of atherosclerosis. These findings support the idea that unhealthy lifestyles should be modified before considering an intervention in work style.