Association of Rotating Night Shift Work with Body Fat Percentage and Fat Mass Index among Female Steelworkers in North China

Abstract

The aim of this study was to evaluate the associations of rotating night shift work with body fat percentage (BF%) and fat mass index (FMI). A cross-sectional study was conducted among 435 female steelworkers, aged 26–57 years in Tangshan, China. BF% was assessed via bioelectrical impedance analysis and FMI was calculated. Different exposure metrics of night shift work were used to examine the effects of night shift work on BF% and FMI. The duration (years), cumulative number (nights), and cumulative length of night shifts (hours) were positively correlated with FMI and BF%, and these relationships were independent of body mass index (BMI). Compared with day workers, night shift workers with an average frequency of night shifts >7 nights/month (odds ratio (OR) 2.50, 95% confidence interval (CI) 1.17 to 5.35) and percentage of hours on night shifts >30% (OR 2.55, 95% CI 1.21 to 5.39) had elevated odds of obesity (BF% ≥ 35.0%). Nonobese night shift workers by the BMI criterion should also be alert to the risk of the excess accumulation of body fat, which is actually responsible for most obesity-associated adverse health consequences. Health interventions for related populations need to be improved, which is currently more focused on overall weight control.

Fat mass index as a screening tool for the assessment of non-alcoholic fatty liver disease

“…The measurement criteria of height, weight, waist circumference and hip circumference (HC) in this study were shown in our previous study 20 . The detailed definitions of BF%, FMI, BMI, waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) have been elaborated in our previous study 20 . Blood pressure measurements were performed three times five-minute intervals using an electronic sphygmomanometer (OMRON, HBP-1100, China), and the participants were required to rest for more than ten minutes.…”

“…This cross-sectional study reported results from the baseline survey of a Chinese occupational cohort conducted among steelworkers in Tangshan City, Hebei Province in north China. The study design and population have been described in detail in our previous studies 19 , 20 . The main exclusion criteria were diagnosed or suspected secondary causes of hepatic fat accumulation such as excess alcohol intake, or serum hepatitis B surface antigen-positivity.…”

“…The values of fat mass and BF% were measured by the Body Composition Analyzer (TANITA BC-420, Japan). The manufacturer’s protocols 18 and the intra-rater reliability 20 of the body composition analyzer of the same brand and model have been described in detail elsewhere. The measurement criteria of height, weight, waist circumference and hip circumference (HC) in this study were shown in our previous study 20 .…”

“…The manufacturer’s protocols 18 and the intra-rater reliability 20 of the body composition analyzer of the same brand and model have been described in detail elsewhere. The measurement criteria of height, weight, waist circumference and hip circumference (HC) in this study were shown in our previous study 20 . The detailed definitions of BF%, FMI, BMI, waist-to-hip ratio (WHR) and waist-to-height ratio (WHtR) have been elaborated in our previous study 20 .…”

The Effect of Shiftwork on Body Composition

“…Another interesting finding of the current study was the increase in BF% with the duration of exposure to shiftwork irrespective of sex. Supporting the fact, a study conducted by Zhang et al, 57 among a group of female steelworkers, also demonstrated that lengthy duration and high-frequency night shiftwork may increase BF% independent of the BMI. A similar study conducted in the Netherlands reported that shiftwork length seems to be positively linked to BMI and WHR regardless of age, sex, smoking history, physical activity, or education 58 …”