[Relation of life style, working posture and job category to body mass index change in young male workers].

The relationships of change in body mass index (BMI) on blood pressure, blood and serum tests, and of life style, working posture and job category on change in BMI after age twenty were investigated in a cross sectional study. A total of 771 male employees aged 21 or older (mean age 29.9 +/- 9.1 years) of a semiconductor factory were examined in December 1993. BMI change of each subject was expressed as percent increase after age twenty. BMI value at age twenty was calculated from self-reported body weight at twenty and height measured at the 1993 health examination. Prevalences of high blood pressure (systolic blood pressure > or = 160 mmHg or diastolic blood pressure > or = 95 mmHg), high blood pressure including borderline hypertension (systolic blood pressure > or = 140 mmHg or diastolic blood pressure > or = 90 mmHg) and abnormal values of serum GOT, GPT, gamma-GPT, total cholesterol, triglyceride, HDL-cholesterol, uric acid and fasting blood glucose were greater in the high BMI change group than in the low BMI change group (Chi-square test, P < 0.1). With the exception of hypertension, these associations remained virtually unchanged after adjusting for age, alcoholic consumption, smoking habits and BMI at 20 years of age by multiple logistic regression analysis. After adjustment for age by the Mantel-Henszael method, increases in BMI after 20 years of age were positively associated with the following eight items (p < 0.05): shorter standing time, shorter walking time, lower meal skipping frequency, shorter meal time, longer sitting time during work, larger meal size, greater frequency of salad consumption, and sedentary work such as clerk and engineer. Greater rice consumption and higher frequency of instant foods consumption were weakly associated with the increase in BMI (0.05 < p < 0.1). Job categories such as clerk and engineer were significantly associated with longer sitting time and shorter meal time, resulting in greater BMI increase after 20 years of age. Multiple logistic regression analysis revealed that shorter standing time, shorter meal time, larger meal size, greater frequency of instant foods consumption and greater frequency of salad consumption were independently correlated with the increase in BMI (p < 0.05). Larger rice consumption was slightly correlated with increasing BMI (0.05 < p < 0.1). This study showed that job category, working posture and food intake patterns were strongly associated with BMI change after age 20 in young male workers. This study provides useful information for health care and health promotion programs in young male workers.