Relationship between Shift Work and BMI; a Meta-Analysis Study

Aims Obesity is one of the most serious health issues in the world. Various factors such as shift work are known as potential risk factors for obesity. Thus this systematic review and meta- analysis evaluated the associations between shift work and Mean Body Mass Index (BMI). Information Methods In October 2020, PubMed, Google Scholar, Scopus, Web of Science, SID, Barakat, IranDoc, and Civilica databases were searched for observational studies in which the relations between the styles of shift works and obesity were investigated. The random-effect model was used to derive the BMI. Subgroup meta-analyses for the study design, particular forms of obesity, and shift work pattern characteristics were performed. Findings The search resulted in 580 documents, of which 217 articles were identified as eligible papers for the meta-analysis. Overall, the pooled Standard Mean Difference (SMD) and 95% Confidence Interval (CI) for shift work rather than day work was 0.082 (ranging from 0.047 to 0.116). Moreover, the results showed that the mean BMI of all of the styles of shift works (Rotation Shift, SMD (95% CI): 0.099 (0.058, 0.141), Night Shift, SMD (95% CI): 0.079 (0.047, 0.11)), except for evening Shift (SMD (95% CI): 0.041 (-0.061 to 0.142)), are higher than day work. Conclusion To minimize the harm, companies should provide shift workers with some advice on an appropriate and healthy diet and lifestyle. Companies that provide meals for their employees should consider a different meal plan for shift workers.