Duration of shiftwork related to body mass index and waist to hip ratio

Abstract

OBJECTIVE: An elevated cardiovascular disease risk for shiftworkers has frequently been reported, however, the mechanism is still unknown. Changes in eating habits, in physical activity or metabolic factors could be involved. In this study we assessed the relationship between body mass index (BMI) as a possible indicator of changed eating habits or metabolic involvement and duration of shiftwork. DESIGN: Data from an ongoing cohort study among 377 shiftworkers and non-shiftworking controls, all starting in a new job were used. Anthropometric measurements were carried out at the start of the assignment. Job history was obtained by a questionnaire. RESULTS: A positive relationship was observed between BMI and waist to hip ratio (WHR) and duration of shiftwork experience, with an adjustment for age. The linear regression coef®cients, with additional adjustments for sex, smoking status, physical activity and educational level were 0.12 kgam 2 per y in shiftwork for BMI (P`0.05) and 0.0016 per y in shiftwork for WHR (P`0.05). CONCLUSIONS: These results suggest a relationship between years worked in shifts with BMI and WHR for both males and females. Whether this might re¯ect an effect of changed dietary habits or a metabolic effect is not yet clear.

Effect of shift work on body mass index: results of a study performed in 319 glucose-tolerant men working in a Southern Italian industry

“…18 Other evidence highlights a positive relationship between BMI and duration of shift work exposure. 19 In particular, employees involved in shift working for more than 5 y had significantly higher BMI than those with no shift work experience. 19 Weight gain in shift workers has been explained by several mechanisms, such as higher calorie intake, 16 changes both in dietary habits (such as eating fewer meals and more snacks) and in the circadian distribution of food intake, 16,28,29 lower physical exercise, 16,30 and changes in sleeping habits.…”

“…All subjects were asked about their work, family and clinical history, and their smoking habits. Since one of the inclusion criteria was to have at least 5 y of working age, that is, a reasonable latency for shift work to exert its effects on cardiovascular risk, 19 33 of 718 subjects were excluded from the study since their working age was lower than 5 y. Among the remaining 685 workers, further 32 individuals were excluded because of documented clinical history of diabetes mellitus (n ¼ 28) or impaired glucose tolerance (IGT) (n ¼ 4).…”

“…[16][17][18][19] Moreover, abdominal fat accumulation is a cardiovascular risk factor stronger than obesity itself, 14 and it is noteworthy that shift workers have been shown to have higher waist-to-hip ratio (WHR) (ie more central fat) than day workers, independently of body mass index (BMI). 20 Among several well known cardiovascular risk factors, total cholesterol [20][21][22] and triglycerides 5,21,23,24 have been shown to be higher in shift workers than in day workers, independently of other lifestyle factors.…”

Predictors of abdominal obesity among 31-y-old men and women born in Northern Finland in 1966

“…All in all, BMI is nevertheless one of the most marked determinants of WHR (Molarius et al, 1999;Lahti-Koski et al, 2000a;Kuh et al, 2002). Apart from its inverse relation to social class (Brunner et al, 1998;Lahmann et al, 2000) and level of education (Marti et al, 1991;LahtiKoski et al, 2000a), WHR has been shown to be associated with several lifestyle factors, such as alcohol consumption (Laws et al, 1990;Sakurai et al, 1997;Dallongeville et al, 1998), smoking (Laws et al, 1990), high intake of dietary saturated fats (Ward et al, 1994), physical inactivity (Laws et al, 1990;Trichopoulou et al, 2001), increased stress and anxiety (Lloyd et al, 1996), shiftwork (van Amelsvoort et al, 1999) and parity (Lahmann et al, 2000). These studies, however, have not taken simultaneously into account earlier lifecourse variables, for example, body size at different ages.…”

The effect of scheduled forced wheel activity on body weight in male F344 rats undergoing chronic circadian desynchronization

“…These disturbances include high body weight gain, 1 body mass index, [2][3][4][5][6][7] waist-to-hip ratio, [6][7][8] prevalence of overweight 9 and obesity, 2,10 serum cholesterol, 8,10 and prevalence of high serum triglyceride and low high-density lipoprotein (HDL)-cholesterol. 10 However, the causal relationship between work shifts and metabolic disturbances has been questioned.…”