Shift work is characterized by schedules that differ from conventional working hours. Night work and work that occurs continuously for 24 hours with rotating shifts also fall within this definition of shift work. During the last few decades, the proportion of shift workers has been increasing. This work system has been described as an important risk factor in the etiology of metabolic disorders and chronic diseases.
The causal mechanisms of this association are not fully elucidated, but observational studies indicate that changes in work schedules result in physiological and behavioral changes in shift workers. These workers suffer from a disruption of the circadian rhythm and, therefore, experience hormonal alterations from being awake at the time biologically reserved for sleep. In addition, in shift work, the reorganization of nighttime and daytime activities involves changes in lifestyle, including eating habits.
Working in shifts can affect eating habits in a variety of aspects. Epidemiological studies have shown differences in relation to the consumption of calories and macronutrients and the quality of the food eaten by shift workers. Changes in meal patterns (i.e., meal frequency, types of meals and times for meals) have also already been previously associated with changes in work schedules or sleep deprivation.
Systematization of the knowledge about the influence of shift work on eating habits is critical in understanding the relationship between work shifts and metabolic disorders and chronic diseases. In this sense, three published review studies on this topic were found. One narrative review described dietary characteristics among shift workers but did not compare dietary characteristics with those of nonshift worker controls. A systematic review investigated dietary habits in conjunction with the nutritional status of workers. In addition, a meta-analysis study focused only on energy intake assessment. Therefore, it is necessary to carry out review studies with a high-quality systematic approach that investigate the association between the timing of work shifts and dietary habits, considering eating habits in a broad way, including quantitative and qualitative assessments of diet, as well as the meal patterns of workers.
Thus, the aim of this study was to perform a systematic review of evidence of the association between shift work and eating habits. We hypothesized that shift workers have irregular eating times, skip main meals, and have a higher consumption of snack meals and foods rich in sugars and fats than daytime workers.