Shift work may be associated with IR syndrome in workers younger than 50 years. These relations may be underestimated mainly by broad definition of shift work and healthy-worker effects.

This study was conducted to determine if there is an association between shift work and risk factors for coronary heart disease (CHD) in Japanese male blue-collar shift workers. Health check-up data on serum lipid concentration and anthropometric indices of 33 three-shift workers and 27 two-shift workers were compared with those of day workers. The average years in age of the shift workers and day workers were 34.5 (SD = 7.1) and 32.7 (SD = 7.6), respectively. Serum total cholesterol levels of three-shift, two-shift and day workers were 5.70 (SD = 1.19) mmol/l, 4.81 (SD = 1.01) mmol/l, 4.98 (SD = 0.95) mmol/l, respectively, and the cholesterol levels of three-shift workers were significantly higher than the other workers (p < 0.05). In addition, the abdominal to hip circumference ratios were 0.905 (SD = 0.060) for three-shift workers and 0.877 (SD = 0.054) for day workers, with a significant difference (p < 0.05). In the present Japanese population, three-shift workers had higher risks of CHD than day workers, which was characterized by higher levels of serum total cholesterol and tendency to central obesity. These findings held when lifestyle factors were taken into account.

Resting heart rate and BP proportionally raise the risk for DM in middle-aged healthy men and women. Moreover, the adverse effects of fast heart rate and high BP are independent of each other as well as of the influences of conventional confounders.

This epidemiologic study was undertaken to determine whether working overtime is associated with anthropometric indices and serum lipids, risk factors for obesity, in white-collar workers. Non-management white-collar male workers were eligible. Body weight and height, waist circumference, skinfold thickness, serum total cholesterol and triglycerides were measured. Weight, height and waist circumference data obtained 3 years previously were also used. Lifestyle information was obtained by means of a self-administered questionnaire. Overtime hours correlated significantly with the 3-year change in body mass index (r = 0.206, p < 0.0017) and waist circumference (r = 0.218, p = 0.0091), but not with either the most recent anthropometric indices or serum lipids. Overtime hours were also intercorrelated (r = 0.436, p < 0.0001) with dinner time. The present study suggested that working overtime is associated with the increases in BMI and waist circumference over a 3-year period although the associations were weak. Additionally, eating habits of those with working overtime might reflect an intervening effect on the anthropometric changes.

We present population data on percentage body fat (%BF) by bioelectrical impedance analysis (BIA) in 12 287 men and 6657 women aged 30 ± 69 y. In addition, we examined relationships among BMI, %BF and serum lipids (totalcholesterol (TC), HDL-cholesterol (HDLC), TCaHDLC ratio, LDL-cholesterol (LDLC) and triglycerides (TG)) in order to determine whether body mass index (BMI, kgam 2 ) or %BF by BIA better re¯ected lipid metabolism. Women had larger %BF than men in all age groups. On the other hand, women aged`60 y had smaller BMI than corresponding men. Regardless of age, BMI was obviously correlated with %BF (r 0.743 ± 0.924). As previously reported, high BMI and high %BF were strongly associated with high serum TCaHDLC ratio and TG, and low serum HDLC rather than high serum TC and LDLC. Compared with BMI, %BF by BIA was better correlated with the serum indices except for serum HDLC. These results were found in both sexes, and there was a trend in which younger subjects had stronger correlations among BMI, %BF and serum lipids. Consequently, %BF by BIA (an index of body composition) better re¯ects serum lipid pro®le than BMI.