Warning: mkdir(): Permission denied in /home/virtual/lib/view_data.php on line 81

Warning: fopen(upload/ip_log/ip_log_2024-09.txt): failed to open stream: No such file or directory in /home/virtual/lib/view_data.php on line 83

Warning: fwrite() expects parameter 1 to be resource, boolean given in /home/virtual/lib/view_data.php on line 84
Long working hours and overweight and obesity in working adults
Skip Navigation
Skip to contents

Ann Occup Environ Med : Annals of Occupational and Environmental Medicine

OPEN ACCESS
SEARCH
Search

Articles

Page Path
HOME > Ann Occup Environ Med > Volume 28; 2016 > Article
Research Article Long working hours and overweight and obesity in working adults
Byung-Mi Kim1, Bo-Eun Lee2, Hye-Sook Park3, Young-Ju Kim4, Young-Ju Suh5,6, Jeong-youn Kim7, Ji-Young Shin3, Eun-Hee Ha3
Annals of Occupational and Environmental Medicine 2016;28(1):36.
DOI: https://doi.org/10.1186/s40557-016-0110-7
Published online: August 22, 2016

1National cancer control Institute, National Cancer Center, Goyang, South Korea

2Environmental Health Research Division, Environmental Health Research Department, National Institute of Environmental Research, Ministry of Environment, Incheon, South Korea

3Department of Preventive Medicine, School of Medicine, Ewha Womans University, Seoul, South Korea

4Department of Obstetrics and Gynecology, School of Medicine, Ewha Womans University, Seoul, South Korea

5Department of Biostatistics, Inha University Hospital and Center for Advanced Medical Education by BK21 project, College of Medicine, Inha University, Shinheung-dong 3ga, Chung-gu, Incheon, Korea

6Chronic Diseases Research Division, Korea Center for Disease Control and Prevention, Seoul, South Korea

7Worker Health Protection Division, Occupational safety and health Bureau, Ministry of labor Government Complex III, Seoul, South Korea

• Received: September 3, 2014   • Accepted: May 11, 2016

© Ha. 2016

Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.

  • 56 Views
  • 0 Download
  • 16 Web of Science
  • 17 Crossref
  • 21 Scopus
prev next
  • Background
    Previous studies have identified a link between gender and the various risk factors associated with obesity. We examined obesity risk factors in working adults to identify the effects of differences in body mass index (BMI) and percentage body fat (PBF) between women and men.
  • Methods
    A total of 1,120 adults agreed to participate in the study. Data from 711 participants, including 411 women and 300 men, were analyzed. Multiple logistic regression analysis was used to estimate the effects of risk factors on obesity and being overweight. In addition, the least-squares (LS) means of both BMI and PBF were estimated by analysis of covariance (ANCOVA) in a generalized linear model. 
  • Results
    Increases in BMI and PBF were significantly related to an age > 50 years and long working hours in women after compensating for confounding factors. Using the PBF criterion, the odds ratio (OR) of being overweight or obese in women > 50 years of age who worked for > 9 h a day was 3.9 (95% confidence interval [CI], 1.05–11.00). For BMI, women who were > 50 years of age and worked for > 9 h a day were 3.82 times (95% CI, 1.31–11.14) more likely to be overweight or obese than those who were < 50 years of age and worked for < 9 h a day.
  • Conclusion
    Obesity in working adults was associated with > 50 years of age and long working hours in women. Further studies are needed to investigate the underlying mechanisms of this relationship and its potential implications for the prevention and management of excess weight and obesity.
Obesity, the accumulation of excess body fat, is recognized as an independent risk factor for a variety of chronic diseases, such as hypertension, ischemic heart disease, fatty liver, cholelithiasis, hyperlipidemia, diabetes, and osteoarthritis. Obesity also affects the development of some types of cancer in men (prostate and colorectal cancers), as well as breast and ovarian cancers in women. Thus, obesity is an important issue in public health [1].
The prevalence of obesity has been increasing in several countries [25]. The Korea National Health and Nutrition Examination Survey has recently reported that the rate of obesity in adults has been steadily increasing each year. In men, there was a significant increase over time in prevalence of obesity (26.8 % for KNHANES I (1998), 37.6 % for KNHANES III (2005), and 38.1 % for KNHANES V (2010–2012); P for trend < 0.0001), and these increases were consistent across all age groups. However, the prevalence of obesity among men has remained stable since KNHANES III. In contrast, the prevalence of obesity in women decreased over time, but the decrease was not significant (P for trend = 0.14) [6]. When comparing the incidence of obesity by gender and age group, men had the highest incidence of obesity in their 40s–50s, while women had the highest incidence in their 50s–60s [6]. 
Previous studies have reported that obesity is more prevalent in women than men mainly because the distribution of a woman’s body fat changes depending on the hormone cycle [7]. The literature suggests that the accelerated increase in total body fat experienced by many middle-aged women is not due to the general aging process, but is a phenomenon triggered by menopause and the withdrawal of estrogens [8].
The determinants of obesity have been shown to be multifactorial and gender-specific [9]. In particular, long working hours have been found to interrupt the recovery of workers from overwork, inhibit performance of regular exercise, and decrease sleep duration [10]. According to the Organization for Economic Cooperation and Development (OECD), the Republic of Korea had the longest working hours until 2007, and the second longest working hours from 2008 to 2011 [11]. An association between long working hours and obesity has been reported in several countries, including Hong Kong, Australia and Finland [1214].
Although studies showed a significant effects of long working hours on male obesity, the association between number of working hours and obesity in the female population was inconclusive. 14.8% more female than male workers are employed in the informal sector [15]. With increasing participation in employment and exposure to poorer labor environments among female compared to male workers, it is becoming more important to study the risk factors in the labor environment on obesity in female workers. However, to the best of our knowledge, few studies have investigated this topic. The main purpose of this study was to explore the relationships between number of working hours and excess weight and obesity among working adults in Seoul, Korea.
Study design and subjects
All respondents were > 40 years of age (range 40 to 78) and had a medical examination at Ewha Womans University Hospital (one of the participants in the Korea Health Examinees Cohort study from June 2005 to March 2006). All participants were given a full written and verbal explanation of the project and each subject provided written consent before enrollment. The participants completed a questionnaire, which included questions about socioeconomic and lifestyle factors. One thousand one hundred twenty subjects responded that they currently had a job. Four hundred nine participants whose data showed missing values for major variables, such as the body mass index (BMI) and percent body fat (PBF), were excluded so that a total of 711 participants (411 women and 300 men) were included in the final analysis, comprising 63.5% of the original group of study subjects (Table 1). The study was approved by the Institutional Review Board (IRB) of Ewha Womans University Hospital in Seoul, South Korea.
Table 1
Characteristics of study subjects by gendera
Variable N (%), Mean ± SD
Women(N = 411) Men(N = 300)
General characteristics
 Age group
  40–49 220(53.5) 141(47)
  50–59 123(37.5) 111(37)
   ≥ 60 57(17.4) 48(16)
 Marital status
  Unmarried 10(2.5) 8(2.7)
  Married 367(91.5) 277(93.9)
  Divorced/Widow/Widower 24(6.0) 10(3.4)
 Educational level
  Low 200(48.7) 129(43)
  Middle 191(46.5) 136(45.3)
  High 20(4.9) 35(11.7)
 Household income (US$/Month)
   < 2,000 21(5.8) 18(6.3)
  2,000–3,000 18(5) 17(6.0)
   ≥ 3,000 321(89.2) 249(87.7)
 Smoking
  Non-smoker 396(96.3) 86(28.7)
  Smoker 15(3.7) 214(71.3)
 Alcohol consumption
  Non-drinking 284(69.1) 54(18)
  Drinking 127(30.9) 246(82)
Anthropometric characteristics
 BMI(kg/m2)* 23.2 ± 2.9 24.5 ± 2.7
  Prevalence of overweight(%)+ 102(24.8 %) 85(28.3 %)
  Prevalence of obesity(%)+ 97 (23.6 %) 134(44.7 %)
 PBF(%)* 27.3 ± 5.3 23.9 ± 4.5
  Prevalence of overweight(%)+ 156 (38.0 %) 115 (38.3 %)
  Prevalence of obesity(%)+ 48 (11.7 %) 136(45.3 %)
 Lean body mass(kg)* 36.9 ± 3.5 48.9 ± 4.5
*Values are Mean ± SD
+Abbreviations. BMI: Body mass index (Cut-off limits of overweight: 23 ≤ BMI (kg/m2) < 25, Cut-off limits of obesity: BMI (kg/m2) ≥25), PBF: Percent body fat (Cut-off limits of overweight: 20 = <PBF (%) < 25 in men and 30 ≤ PBF (%) < 35 in women, Cut-off limits of obesity: men’s PBF (%) ≥ 25; women’s PBF (%) ≥ 35)
aDifferences between sexes: *P < 0.05 obtained by students t-test, **P < 0.05 obtained by χ 2-test
Anthropometric measurements
Anthropometric and body composition measurements were performed by two experienced nurses. Height was measured Using an ultrasonic height meter (FA-92H; Panics, Korea) and weight was measured without shoes and heavy clothing using a body composition analyzer. The height and weight measurements were recorded to the nearest 0.1 cm and 0.1 kg, respectively.
For the body composition analysis, the PBF and muscle mass were measured using a body composition analyzer (Zeus 9.9 Jawon medical Co. Ltd., Seoul, Korea, 2013) utilizing a bioelectrical impedance analysis (BIA), which is widely used in obesity clinics for the assessment of body composition and does not require any exposure to radiation.
Case definition
Categories were selected according to the standards of the World Health Organization (WHO) Western Pacific Regional Office proposal [9], which is widely used in Korea to define individuals that are of healthy weight (BMI 20.0–23.0 kg/m2), overweight (23–24.9 kg/m2), and obese (BMI ≥ 25 kg/m2). Men with PBFs < 20 %, 20–24 %, and ≥ 25 % were classified as healthy weight, overweight, or obese, respectively, while women were classified as healthy weight, overweight, or obese with PBFs of <30 %, 30–34 %, and ≥35 %, respectively [16].
Socioeconomic and lifestyle factors
We included socioeconomic factors, including age, marital status (unmarried, married, and divorced/widow/widower), educational level (<12, 12–16, and ≥16 years) and monthly household income (<200, 200–300, and ≥300 × 104 won) in the questionnaire. For lifestyle factors, we investigated smoking (non-smoker or smoker), alcohol consumption (drinker or non-drinker), regular exercise (yes or no), average number of working hours per day, average number of sleeping hours per day, and average occupational sitting time. Occupational sitting times were dichotomized at the median value of 4 h/day and categorized as: <4 h/day and ≥4 h/day.
Statistical analysis
Descriptive statistics for general characteristics and anthropometric measures were calculated separately for each gender. To analyze factors related to obesity and being overweight according to gender, we performed a χ2 test or an analysis of variance (ANOVA). We used multiple logistic regression to determine the association between obesity-related risk factors and BMI and PBF adjusted for confounding factors except for the targeted variable itself. The least squares means (LS means) of BMI and PBF according to the risk factors were estimated by analysis of covariance (ANCOVA) in the generalized linear model. All reported p values were calculated by two-sided tests at a significance level of 5 %. All analyses were performed using SAS (version 9.3; SAS Institute, Cary, NC, USA).
Table 1 lists the characteristics of the study participants by gender. Approximately one-half of the study subjects were in their 40s and were college graduates. The percentages of women who smoked cigarettes and drank alcohol were 3.7 % and 30.9 %, respectively. Men had a higher proportion of being obesity (44.7 %) than women (23.6 %, p < 0.05). The proportion of obesity based on the PBF was higher in men (45.3 %) than in women (11.7 %).
Table 2 shows the proportion of each gender that was overweight or obese individuals according to socioeconomic and lifestyle factors. In women, age and a low level of education were significantly related with being overweight, as based on BMI and PBF. In addition, the proportion of overweight individuals was significantly higher in women who worked > 9 h a day. In contrast, in men none of the socioeconomic and lifestyle factors were associated with being overweight.
Table 2
Prevalence of socioeconomic and lifestyle characteristics for being overweight or obese based on BMI and PBF by gender
BMI (kg/m2) PBF (%)
Women Men Women Men
Variable Controls* Cases+ Controls* Cases+ Controls* Cases+ Controls* Cases+
(N = 207) (N = 204) (N = 81) (N = 219) (N = 207) (N = 204) (N = 49) (N = 251)
Age group
 40–49 126 (59.4) 94 (47.2) 34 (42) 107 (42) 132 (63.8) 88 (43.1) 25 (51) 116 (46.2)
 50–59 69 (32.6) 79 (39.7) 31 (38.3) 80 (38.3) 67 (32.4) 81 (39.7) 17 (34.7) 94 (37.5)
  ≥ 60 17 (8) 26 (13.1) 16 (19.8) 32 (19.8) 8 (3.9) 35 (17.2) 7 (14.3) 41 (16.3)
p = 0.01 p = 0.21 p < 0.0001 p = 0.55
Marital status
 Unmarried 5 (2.4) 5 (2.6) 3 (3.8) 5 (2.3) 5 (2.5) 5 (2.5) 1 (2) 7 (2.9)
 Married 191 (92.3) 176 (90.7) 74 (92.5) 203 (94.4) 187 (92.6) 180 (90.5) 45 (91.8) 232 (94.3)
 Divorced/Widow/Widower 11 (5.3) 13 (6.7) 3 (3.8) 7 (3.3) 10 (5) 14 (7) 3 (6.1) 7 (2.9)
p = 0.67 p = 0.79 p = 0.48 p = 0.29
Educational level
 Low 89 (42) 111 (55.8) 36 (44.4) 93 (42.5) 89 (43) 111 (54.4) 23 (46.9) 106 (42.2)
 Middle 110 (51.9) 81 (40.7) 40 (49.4) 96 (43.8) 104 (50.2) 87 (42.7) 22 (44.9) 114 (45.4)
 High 13 (6.1) 7 (3.5) 5 (6.2) 30 (13.7) 14 (6.8) 6 (2.9) 4 (8.2) 31 (12.4)
p = 0.005 p = 0.28 p = 0.01 p = 0.40
Income (US$/Month)
  < 2,000 12 (6.6) 9 (5.1) 4 (5) 14 (6.9) 11 (6.1) 10 (5.6) 2 (4.1) 16 (6.8)
 2,000-3,000 8 (4.4) 10 (5.6) 5 (6.3) 12 (5.9) 7 (3.9) 11 (6.2) 2 (4.1) 15 (6.4)
  ≥ 3,000 162 (89) 159 (89.3) 71 (88.8) 178 (87.3) 163 (90.1) 158 (88.3) 45 (91.8) 204 (86.8)
p = 0.73 p = 0.63 p = 0.81 p = 0.35
Smoking
 Non-smoker 207 (97.6) 189 (95) 25 (30.9) 61 (27.9) 202 (97.6) 194 (95.1) 15 (30.6) 71 (28.3)
 Smoker 5 (2.4) 10 (5) 56 (69.1) 158 (72.2) 5 (2.4) 10 (4.9) 34 (69.4) 180 (71.7)
p = 0.24 p = 0.71 p = 0.28 p = 0.88
Alcohol consumption
 Non-drinking 151 (71.2) 133 (66.8) 14 (17.3) 40 (18.3) 146 (70.5) 138 (67.7) 10 (20.4) 44 (17.5)
 Drinking 61 (28.8) 66 (33.2) 67 (82.7) 179 (81.7) 61 (29.5) 66 (32.4) 39 (79.6) 207 (82.5)
p = 0.39 p = 0.98 p = 0.60 p = 0.78
Working hours
  < 9 h/day 193 (93.7) 169 (86.7) 47 (58.8) 146 (67.6) 189 (93.6) 173 (86.9) 29 (60.4) 164 (66.1)
  ≥ 9 h/day 13 (6.3) 26 (13.3) 33 (41.3) 70 (32.4) 13 (6.4) 26 (13.1) 19 (39.6) 84 (33.9)
p = 0.03 p = 0.20 p = 0.04 p = 0.55
Occupational sitting time
  < 4 h/day 152 (71.7) 132 (66.3) 28 (34.6) 74 (33.8) 149 (72) 135 (66.2) 14 (28.6) 88 (35.1)
  ≥ 4 h/day 60 (28.3) 67 (33.7) 53 (65.4) 145 (66.2) 58 (28) 69 (33.8) 35 (71.4) 163 (64.9)
p = 0.28 p = 1.00 p = 0.24 p = 0.48
Regular exercise
 No 89 (42.4) 73 (36.9) 34 (42.5) 84 (38.7) 79 (38.5) 83 (40.9) 19 (38.8) 99 (39.9)
 Yes 121 (57.6) 125 (63.1) 46 (57.5) 133 (61.3) 126 (61.5) 120 (59.1) 30 (61.2) 149 (60.1)
p = 0.30 p = 0.65 p = 0.70 p = 1.00
Sleeping hours
  > 9 h/day 135 (65.5) 146 (75.7) 59 (72.8) 157 (72) 132 (65.4) 149 (75.6) 35 (71.4) 181 (72.4)
    9 h/day 71 (34.5) 47 (24.4) 22 (27.2) 61 (28) 70 (34.7) 48 (24.4) 14 (28.6) 69 (27.6)
p = 0.04 p = 1.00 p = 0.03 p = 1.00
*Controls. BMI: Body mass index (Cut-off limits of overweight: BMI (kg/m2) <25, PBF: Percent body fat (Cut-off limits of overweight: men’s BF (%) < 20; women’s BF (%) < 30)
+Cases. BMI: Body mass index (Cut-off limits of overweight: BMI (kg/m2) ≥25, PBF: Percent body fat (Cut-off limits of overweight: men’s BF (%) ≥ 20; women’s BF (%) ≥ 3
Working hours, occupational sitting time and Sleeping time were dichotomized at the median
The results obtained from the logistic regression analyses for BMI and PBF are presented in Table 3. The ORs of being overweight or obese in women for both BMI and PBF were significantly higher in older women. Women with a lower educational level were more likely to be overweight or obese. Among women who worked >9 h a day, the risk for becoming overweight or obese increased according to both the BMI and PBF criteria after adjusting for confounding factors such as age, educational level, smoking, alcohol consumption, number of hours worked, sitting time at work, and number of sleep hours. Based on the BMI and PBF, the ORs for obesity attributable to long working hours were 2.42 (95 % CI, 1.05–5.57) and 2.50 (95 % CI, 1.07–5.79), respectively.
Table 3
Odds ratio and 95 % Confidence intervals of overweight or obese based on BMI and PBF by socioeconomic and lifestyle characteristics for women and men
BMI (kg/m2) PBF (%)
Women Men Women Men
Variable Crude OR Adjusted OR* Crude OR Adjusted OR* Crude OR Adjusted OR* Crude OR Adjusted OR*
(95 % CI) (95 % CI) (95 % CI) (95 % CI) (95 % CI) (95 % CI) (95 % CI) (95 % CI)
Socio-demographic factors
 Age group
  40–49 1 1 1 1 1 1 1 1
  50–59 1.54 1.47 0.82 0.66 1.81 1.96 1.19 1.41
(1.01–2.33) (0.89–2.42) (0.47–1.45) (0.34–1.28) (1.19–2.76) (1.18–3.24) (0.61–2.34) (0.66–3.02)
  60+ 2.05 2.49 0.64 0.48 6.56 7.37 1.26 1.65
(1.05–4.00) (1.16–5.33) (0.31–1.30) (0.21–1.11) (2.91–14.81) (3.06–17.76) (0.51–3.14) (0.57–4.76)
 Marital status
  Unmarried 1 1 1 1 1 1 1 1
  Married 0.92 0.74 1.65 1.65 0.96 1.41 0.74 0.94
(0.26–3.24) (0.17–3.18) (0.38–7.06) (0.35–7.71) (0.27–3.38) (0.30–6.65) (0.09–6.13) (0.11–8.35)
  Divorced, Widow/Widower 1.18 0.51 1.4 0.83 1.4 0.75 0.33 0.14
(0.27–5.18) (0.09–2.89) (0.20–10.03) (0.09–7.49) (0.32–6.16) (0.12–4.7) (0.03–4.04) (0.01–2.09)
 Educational level
  Low 1 1 1 1 1 1 1 1
  Middle 0.59 0.72 0.93 0.87 0.67 0.87 1.12 1.29
(0.40–0.88) (0.45–1.16) (0.55–1.58) (0.48–1.59) (0.45–1.00) (0.54–1.41) (0.59–2.14) (0.64–2.61)
  High 0.43 0.20 2.32 2.60 0.34 0.21 1.68 1.80
(0.17–1.13) (0.05–0.78) (0.84–6.45) (0.81–8.36) (0.13–0.93) (0.05–0.85) (0.54–5.23) (0.54–6.02)
Income (US$/Month)
  < 2,000 1 1 1 1 1 1 1 1
 2,000–3,000 1.67 1.72 0.69 0.42 1.73 1.63 0.94 0.99
(0.47–5.93) (0.41–7.31) (0.15–3.15) (0.08–2.33) (0.48–6.2) (0.37–7.20) (0.12–7.52) (0.11–9.07)
  ≥ 3,000 1.31 1.29 0.72 0.40 1.07 0.82 0.57 0.41
(0.54–3.19) (0.48–3.48) (0.23–2.25) (0.10–1.57) (0.44–2.58) (0.30–2.24) (0.13–2.55) (0.08–2.03)
Lifestyle factors
 Smoking
  Non-smoker 1 1 1 1 1 1 1 1
  Smoker 2.19 1.87 1.16 1.47 2.08 1.86 1.12 1.25
(0.74–6.52) (0.55–6.39) (0.66–2.02) (0.77–2.81) (0.70–6.20) (0.54–6.43) (0.57–2.18) (0.58–2.67)
 Alcohol consumption
  Non-drinking 1 1 1 1 1 1 1 1
  Drinking 1.23 1.39 0.94 0.91 1.15 1.44 1.21 1.70
(0.81–1.87) (0.85–2.25) (0.48–1.83) (0.43–1.96) (0.75–1.74) (0.88–2.37) (0.56–2.60) (0.73–3.93)
 Working hours
   < 9 h/day 1 1 1 1 1 1 1 1
   ≥ 9 h/day 2.28 2.42 0.68 0.46 2.19 2.50 0.78 0.63
(1.14–4.59) (1.05–5.57) (0.40–1.16) (0.24–0.87) (1.09–4.39) (1.07–5.79) (0.41–1.48) (0.30–1.32)
Occupational sitting time
  < 4 h/day 1 1 1 1 1 1 1 1
  ≥ 4 h/day 1.29 0.96 1.04 1.16 1.26 0.98 0.85 0.91
(0.85–1.96) (0.53–1.76) (0.61–1.77) (0.63–2.12) (0.78–2.06) (0.53–1.83) (0.46–1.57) (0.45–1.85)
 Regular exercise
  No 1 1 1 1 1 1 1 1
  Yes 1.26 1.04 1.17 1.31 0.91 0.81 0.95 0.89
(0.85–1.88) (0.65–1.66) (0.70–1.97) (0.74–2.33) (0.61–1.35) (0.5–1.32) (0.51–1.79) (0.46–1.74)
 Sleeping hours
   > 9 h/day 1 1 1 1 1 1 1 1
     9 h/day 0.61 0.66 1.04 1.05 0.61 0.65 0.95 0.79
(0.40–0.95) (0.40–1.09) (0.59–1.85) (0.56–1.99) (0.39–0.94) (0.39–1.10) (0.48–1.88) (0.39–1.63)
*Adjusted for confounding factors except for the targeted variable itself. The confounding factors involve age, educational level, smoking, alcohol consumption, working hours, daily occupational sitting time, and sleeping hours (h/day)
Figure 1 compares the estimated LS means of BMI and PBF by gender according to age and number of working hours. BMI and PBF significantly increased with age and number of working hours in women after adjusting for education, smoking, alcohol consumption, and the average number of sleep hours a day. 
Fig. 1
Levels of BMI and PBF by gender according to daily working hours and age groups. Levels were adjusted for educational level, smoking, alcohol consumption, working hours, and sleeping time (hours/day). Working hours and age group were dichotomized at the median. LS-means: least squares means
40557_2016_110_Fig1_HTML.jpg
The ORs of being overweight or obese for the combined effects of age and long working hours at work are given in Table 4. Using the PBF criterion, the OR of being overweight or obese in women > 50 years of age who worked > 9 h a day was 3.9 (95 % CI, 1.05–11.00). For BMI, women > 50 years of age who worked > 9 h a day were 3.56 times (95 % CI, 1.03–12.37) more likely to be overweight or obese than those who were <50 years of age and worked < 9 h a day.
Table 4
Combined effects of age and daily working hours for overweight or obesity based on BMI and PBF criterion in women
Category N (%) Odds ratios (95 % Confidence Intervals)
BMI PBF
Crude Adjusted* Crude Adjusted*
Group1 (Age < 50 and working hours < 9) 263 (37.73) 1 1 1 1
Group2 (Age ≥ 50 and working hours < 9) 292 (41.89) 1.69(1.11–2.56) 1.68(1.04–2.73) 2.66(1.67–3.91) 2.87(1.75–4.69)
Group3 (Age < 50 and working hours ≥ 9) 87 (12.48) 2.39(0.94–6.03) 2.34(0.77–7.11) 2.60(1.32–8.90) 2.73(1.19–12.06)
Group4 (Age ≥ 50 and working hours ≥ 9) 55 (7.89) 3.82(1.31–11.14) 3.56(1.03–12.37) 3.43(1.23–9.54) 3.90(1.05–11.00)
*Adjusted for confounding factors except for the targeted variable itself. The confounding factors involve age, educational level, smoking, alcohol consumption, working hours, daily occupational sitting time, and sleeping hours (h/day). Working hours and age group were dichotomized at the median
We found associations among obesity (BMI and PBF), age > 50 years, and long work hours in female workers. Women > 50 years of age had a higher incidence of obesity and being overweight than other age groups. Data from large population studies have shown that mean body weight and BMI gradually increase during most of the adult life and reach peak values at 50–59 years of age in women [1720]. This may be explained by women’s weight rapidly increasing as their physical activity and energy consumption decrease following menopause [21]. Obesity may also exaggerate unfavorable lipid profiles in aging and menopausal women. Some studies have reported a more frequent age-related increase in the prevalence of being overweight or obese [7, 22] in females than in males [23] In addition, studies have reported a greater increase in fat mass and waist circumference or abdominal skinfold thickness in postmenopausal compared to premenopausal women [2325] An increase in abdominal lipoprotein lipase activity is observed after the withdrawal of estrogens, which leads to the local elevation of free fatty acids and the accumulation of abdominal fat [26, 27].
Our data showed that higher mean number of daily working hours was associated with higher BMI and PBF. A significant association was identified between obesity and working >9 h a day among females. A previous study in Korea also reported a relationship between long working hours and obesity, but the relationship was not statistically significant [28].
The pathology of obesity as an imbalance between energy intake, multifactor, and energy expenditure is the most important mechanism inducing obesity. Inadequate working conditions linked to the induction of the stress response, and poor lifestyle factors such as long working hours, may increase the risk for obesity [29], When stressful events affect the hypothalamic pituitary adrenal (HPA) axis glucocorticoids are released as end hormones. Glucocorticoids inhibit the positive effects of the growth and thyroid hormones on lipolysis and muscle anabolism [30]. Poor lifestyle factors have also been linked to hormonal factors such as reduced levels of leptin, [31] an adipokine strongly linked to appetite and fat storage that increases the risk for obesity [32]. Hence, the association between long working hours and obesity identified in the current study might be caused by the induction of a stress response as a reaction to working long hours and its associated metabolic effects [33].
Asian women generally assume much of the responsibility for housework. This cultural norm increases stress among female workers, who have less time to complete household duties after long hours spent at the workplace. A longitudinal study reported that women are more vulnerable to anxiety due to overwork than men [34]. The results of the current study suggest that working long hours induces chronic stress, which can increase the risk for obesity in Asian women. Therefore, attention should be paid to the working hours of women to reduce their risk for obesity. Several researchers have suggested that long working hours can lead to poor sleeping habits and less time for exercise and maintaining a balanced diet [35]. which are strongly linked to obesity and increased risk for cardiovascular diseases.
Our study had various strengths as well as limitations. The cross-sectional analyses did not allow us to determine the temporality of the associations, and the data were old. In addition, physical activity and diet may be important confounding variables in the association between obesity and number of working hours, which were not considered in this study due to a lack of data. In other words, obesity and its related health conditions can decrease work performance, and an obese worker might need more time to complete the job demand compared to a healthy worker [13, 36, 37]. This could have biased our results. Hence, careful consideration is needed to interpret our results accurately, and an appropriate prospective cohort study is needed to elucidate this causal relationship. However, we used PBF as an indicator of obesity and employed the BIA method to precisely diagnose obesity. BIA is a widely used method for estimating body composition and has increasingly been used in Korea [38]. The technology is relatively simple, quick, and noninvasive. It is currently used in such diverse settings as the offices of private clinicians, health clubs, hospitals, and across a spectrum of ages, body weights, and disease states. Despite a general perception among the public that BIA measures body fat, the technology actually determines the electrical impedance of body tissues, which provides an estimate of total body water.
In conclusion, obesity was associated with aging and long working hours in female workers in Korea. Further studies are needed to investigate the underlying mechanisms of this relationship and its potential implications for the prevention and management of obesity.
This work was supported by Ewha Global Top 5 project (2012).
Authors’ Contributions
All the authors have read and approved the final manuscript.
Competing interests
The authors declared that they have no competing interests.

ANCOVA

Analysis of covariance

BIA

Bioelectrical Impedance Analysis

BMI

Body Mass Index

IRB

Institutional Review Board

LS means

Least Squares means

MONICA

Monitoring Trends and Determinants in Cardiovascular Disease

PBF

Percentage body fat

WHO

World Health Organizations
  • 1. Keeffe EB, Adesman PW, Stenzel P, Palmer RM. Steatosis and cirrhosis in an obese diabetic. Dig Dis Sci 1987;32(4):441–445. 10.1007/BF01296300. 3829884.ArticlePubMedPDF
  • 2.
  • 3. Wang Y, Beydoun MA. The obesity epidemic in the United States--gender, age, socioeconomic, racial/ethnic, and geographic characteristics: a systematic review and meta-regression analysis. Epidemiol Rev 2007;29:6–28. 10.1093/epirev/mxm007. 17510091.ArticlePubMed
  • 4.
  • 5.
  • 6. Kim HJ, Kim Y, Cho Y, Jun B, Oh KW. Trends in the prevalence of major cardiovascular disease risk factors among Korean adults: results from the Korea National Health and Nutrition Examination Survey, 1998–2012. Int J Cardiol 2014;174(1):64–72. 10.1016/j.ijcard.2014.03.163. 24742812.ArticlePubMed
  • 7. Flegal KM, Carroll MD, Ogden CL, Johnson CL. Prevalence and trends in obesity among US adults, 1999–2000. JAMA 2002;288(14):1723–1727. 10.1001/jama.288.14.1723. 12365955.ArticlePubMed
  • 8. Martinez JA, Kearney JM, Kafatos A, Paquet S, Martínez-Gonzélez MA. Variables independently associated with self-reported obesity in the European Union. Public Health Nutr 1999;2(1a):125–133. 10.1017/S1368980099000178. 10933632.ArticlePubMed
  • 9.
  • 10.
  • 11. ..
  • 12. Lallukka T, Sarlio-Lahteenkorva S, Kaila-Kangas L, Pitkaniemi J, Luukkonen R, Leino-Arjas P. Working conditions and weight gain: a 28-year follow-up study of industrial employees. Eur J Epidemiol 2008;23(4):303–310. 10.1007/s10654-008-9233-7. 18322807.ArticlePubMedPDF
  • 13.
  • 14. Ostry AS, Radi S, Louie AM, LaMontagne AD. Psychosocial and other working conditions in relation to body mass index in a representative sample of Australian workers. BMC Public Health 2006;6:53. 10.1186/1471-2458-6-53. 16512915.ArticlePubMedPMCPDF
  • 15. Kong M-H. Economic Development and Women’s Status in Korea. Contemp South Korean Soc 2013;26:41.
  • 16. Gynaecol ANZJO. 1. WHO: Obesity: preventing and managing the global epidemic. Report of a WHO consultation. World Health Organ Tech Rep Ser 2000;894:1–253.
  • 17. Flegal KM, Carroll MD, Kuczmarski RJ, Johnson CL. Overweight and obesity in the United States: prevalence and trends, 1960–1994. Int J Obes Relat Metab Disord 1998;22(1):39–47. 10.1038/sj.ijo.0800541. 9481598.ArticlePubMedPDF
  • 18. Mokdad AH, Bowman BA, Ford ES, Vinicor F, Marks JS, Koplan JP. The continuing epidemics of obesity and diabetes in the United States. Jama 2001;286(10):1195–1200. 10.1001/jama.286.10.1195. 11559264.ArticlePubMed
  • 19. Kuskowska-Wolk A, Rössner S. Body mass distribution of a representative adult population in Sweden. Diabetes Res Clin Pract 1990;10:S37–S41. 10.1016/0168-8227(90)90138-J. 2286149.ArticlePubMed
  • 20. Hedley AA, Ogden CL, Johnson CL, Carroll MD, Curtin LR, Flegal KM. Prevalence of overweight and obesity among US children, adolescents, and adults, 1999–2002. JAMA 2004;291(23):2847–2850. 10.1001/jama.291.23.2847. 15199035.ArticlePubMed
  • 21. Haarbo J, Marslew U, Gotfredsen A, Christiansen C. Postmenopausal hormone replacement therapy prevents central distribution of body fat after menopause. Metabolism 1991;40(12):1323–1326. 10.1016/0026-0495(91)90037-W. 1961129.ArticlePubMed
  • 22. Godsland I, Wynn V, Crook D, Miller N. Sex, plasma lipoproteins, and atherosclerosis: prevailing assumptions and outstanding questions. Am Heart J 1987;114(6):1467–1503. 10.1016/0002-8703(87)90552-7. 3318361.Article
  • 23. Iwao S, Iwao N, Muller DC, Elahi D, Shimokata H, Andres R. Effect of aging on the relationship between multiple risk factors and waist circumference. J Am Geriatr Soc 2000;48(7):788–794. 10.1111/j.1532-5415.2000.tb04754.x. 10894318.ArticlePubMed
  • 24. Trémollieres FA, Pouilles J-M, Ribot CA. Relative influence of age and menopause on total and regional body composition changes in postmenopausal women. Am J Obstet Gynecol 1996;175(6):1594–1600. 10.1016/S0002-9378(96)70111-4. 8987946.ArticlePubMed
  • 25. Boynton A, Neuhouser ML, Sorensen B, McTiernan A, Ulrich CM. Predictors of diet quality among overweight and obese postmenopausal women. J Am Diet Assoc 2008;108(1):125–130. 10.1016/j.jada.2007.10.037. 18155998.ArticlePubMed
  • 26. Mayes J, Watson G. Direct effects of sex steroid hormones on adipose tissues and obesity. Obes Rev 2004;5(4):197–216. 10.1111/j.1467-789X.2004.00152.x. 15458395.ArticlePubMed
  • 27.
  • 28. Jang T-W, Kim H-R, Lee H-E, Myong J-P, Koo J-W. Long work hours and obesity in Korean adult workers. J Occup Health 2013;55(5):359–366. 10.1539/joh.13-0043-OA. 23892643.ArticlePubMedPDF
  • 29. Porter JS, Bean MK, Gerke CK, Stern M. Psychosocial factors and perspectives on weight gain and barriers to weight loss among adolescents enrolled in obesity treatment. J Clin Psychol Med Settings 2010;17(2):98–102. 10.1007/s10880-010-9186-3. 20119710.ArticlePubMedPDF
  • 30. Chrousos G. The role of stress and the hypothalamic-pituitary-adrenal axis in the pathogenesis of the metabolic syndrome: neuro-endocrine and target tissue-related causes. Int J Obes Relat Metab Disord 2000;24:S50–55. 10.1038/sj.ijo.0801278. 10997609.ArticlePubMedPDF
  • 31. Chaput JP, Després JP, Bouchard C, Tremblay A. Short sleep duration is associated with reduced leptin levels and increased adiposity: results from the Quebec family study. Obesity 2007;15(1):253–261. 10.1038/oby.2007.512. 17228054.ArticlePubMed
  • 32. Forbes S, Bui S, Robinson BR, Hochgeschwender U, Brennan MB. Integrated control of appetite and fat metabolism by the leptin-proopiomelanocortin pathway. Proc Natl Acad Sci 2001;98(7):4233–4237. 10.1073/pnas.071054298. 11259669.ArticlePubMedPMC
  • 33. Flier JS, Elmquist JK. A good night’s sleep: future antidote to the obesity epidemic? Ann Intern Med 2004;141(11):885–886. 10.7326/0003-4819-141-11-200412070-00014. 15583232.ArticlePubMed
  • 34.
  • 35. Maruyama S, Morimoto K. Effects of long workhours on life-style, stress and quality of life among intermediate Japanese managers. Scand J Work Environ Health 1996;22:353–359. 10.5271/sjweh.153. 8923608.ArticlePubMed
  • 36. Calle EE, Kaaks R. Overweight, obesity and cancer: epidemiological evidence and proposed mechanisms. Nat Rev Cancer 2004;4(8):579–591. 10.1038/nrc1408. 15286738.ArticlePubMedPDF
  • 37. James PT, Leach R, Kalamara E, Shayeghi M. The worldwide obesity epidemic. Obes Res 2001;9(S11):228S–233S. 10.1038/oby.2001.123. 11707546.ArticlePubMed
  • 38. Kang S-J, Song Y, Kim D-Y, Kim S-H, Park J-H. Validation of Bioelectrical Impedance Analyzer for Measuring Percentage of Body Fat. Fort Worth, Texas: 2008 AAHPERD National Convention and Exposition: 2008. 2008.

Figure & Data

REFERENCES

    Citations

    Citations to this article as recorded by  
    • Relationship between consumption of high fat, sugar or sodium (HFSS) food and obesity and non-communicable diseases
      Sasinee Thapsuwan, Sirinya Phulkerd, Aphichat Chamratrithirong, Rossarin Soottipong Gray, Nongnuch Jindarattanaporn, Nutnicha Loyfah, Natjera Thongcharoenchupong, Umaporn Pattaravanich
      BMJ Nutrition, Prevention & Health.2024; 7(1): 78.     CrossRef
    • Fenugreek (Trigonella foenum-graecum L.) Modulates Energy Metabolism and Anti-inflammatory Response in Obesity via Combinatorial Analysis
      Fong Fong Liew, Theysshana Visuvanathan, Shalini Vellasamy
      The Natural Products Journal.2023;[Epub]     CrossRef
    • The association between long working hours and obstructive sleep apnea assessed by STOP-BANG score: a cross-sectional study
      Dong-Wook Lee, Jongin Lee
      International Archives of Occupational and Environmental Health.2023; 96(2): 191.     CrossRef
    • The social determinants of health influencing obesity for the aged in the Pakpoon community context: A qualitative study
      Pornchanuch Chumpunuch, Urai Jaraeprapal
      International Journal of Nursing Sciences.2022; 9(2): 211.     CrossRef
    • You Can’t Avoid Shift Work? Then Focus on Body Fat Rather than Weight
      Eun Kyung Lee
      Endocrinology and Metabolism.2022; 37(5): 756.     CrossRef
    • Maternal working hours and smoking and drinking in adolescent children: based on the Korean National Health and Nutrition Examination Survey VI and VII
      Tae-Hwi Park, Yong-Duk Ahn, Jeong-Bae Rhie
      Annals of Occupational and Environmental Medicine.2021;[Epub]     CrossRef
    • Long working hours are associated with a higher risk of non-alcoholic fatty liver disease: A large population-based Korean cohort study
      Yesung Lee, Eunchan Mun, Soyoung Park, Woncheol Lee, Jee-Fu Huang
      PLOS ONE.2021; 16(7): e0255118.     CrossRef
    • Long Working Hours and Risk of Nonalcoholic Fatty Liver Disease: Korea National Health and Nutrition Examination Survey VII
      Eyun Song, Jung A. Kim, Eun Roh, Ji Hee Yu, Nam Hoon Kim, Hye Jin Yoo, Ji A. Seo, Sin Gon Kim, Nan Hee Kim, Sei Hyun Baik, Kyung Mook Choi
      Frontiers in Endocrinology.2021;[Epub]     CrossRef
    • The causes of obesity: an in-depth review
      Tahir Omer
      Advances in Obesity, Weight Management & Control.2020; 10(4): 90.     CrossRef
    • Association between Occupational Characteristics and Overweight and Obesity among Working Korean Women: The 2010–2015 Korea National Health and Nutrition Examination Survey
      Mi-Jung Eum, Hye-Sun Jung
      International Journal of Environmental Research and Public Health.2020; 17(5): 1585.     CrossRef
    • Factors Associated with the Nutritional Status among Male Workers of Iron and Steel Industries in Bara District, Nepal
      Raj Kumar Sangroula, Hari Prasad Subedi, Kalpana Tiwari
      Journal of Nutrition and Metabolism.2020; 2020: 1.     CrossRef
    • Obesity Fact Sheet in Korea, 2019: Prevalence of Obesity and Abdominal Obesity from 2009 to 2018 and Social Factors
      Ga Eun Nam, Yang-Hyun Kim, Kyungdo Han, Jin-Hyung Jung, Eun-Jung Rhee, Seong-Su Lee, Dae Jung Kim, Kwan-Woo Lee, Won-Young Lee
      Journal of Obesity & Metabolic Syndrome.2020; 29(2): 124.     CrossRef
    • Gender differences and occupational factors for the risk of obesity in the Italian working population
      C. Di Tecco, L. Fontana, G. Adamo, M. Petyx, S. Iavicoli
      BMC Public Health.2020;[Epub]     CrossRef
    • Long working hours, anthropometry, lung function, blood pressure and blood-based biomarkers: cross-sectional findings from the CONSTANCES study
      Marianna Virtanen, Linda Magnusson Hansson, Marcel Goldberg, Marie Zins, Sari Stenholm, Jussi Vahtera, Hugo Westerlund, Mika Kivimäki
      Journal of Epidemiology and Community Health.2019; 73(2): 130.     CrossRef
    • Physical fitness, musculoskeletal disorders and body mass index in transport drivers from Barranquilla, Colombia
      Martha Mendinueta-Martínez, Yaneth Herazo-Beltrán, José Vidarte-Claros, Estela Crissien-Quiroz, Roberto Rebolledo-Cobos
      Revista de la Facultad de Medicina.2019; 67(4): 407.     CrossRef
    • Auswirkungen verkürzter Ruhezeiten auf Gesundheit und Work-Life-Balance bei Vollzeitbeschäftigten: Ergebnisse der BAuA-Arbeitszeitbefragung 2017
      Nils Backhaus, Corinna Brauner, Anita Tisch
      Zeitschrift für Arbeitswissenschaft.2019; 73(4): 394.     CrossRef
    • Evaluation for Fatigue and Accident Risk of Korean Commercial Bus Drivers
      Hogil Kim, Tae-Won Jang, Hyoung-Ryoul Kim, Seyoung Lee
      The Tohoku Journal of Experimental Medicine.2018; 246(3): 191.     CrossRef

    • PubReader PubReader
    • ePub LinkePub Link
    • Cite
      CITE
      export Copy Download
      Close
      Download Citation
      Download a citation file in RIS format that can be imported by all major citation management software, including EndNote, ProCite, RefWorks, and Reference Manager.

      Format:
      • RIS — For EndNote, ProCite, RefWorks, and most other reference management software
      • BibTeX — For JabRef, BibDesk, and other BibTeX-specific software
      Include:
      • Citation for the content below
      Long working hours and overweight and obesity in working adults
      Ann Occup Environ Med. 2016;28:36  Published online August 22, 2016
      Close
    • XML DownloadXML Download
    Figure
    • 0
    Related articles
    Long working hours and overweight and obesity in working adults
    Image
    Fig. 1 Levels of BMI and PBF by gender according to daily working hours and age groups. Levels were adjusted for educational level, smoking, alcohol consumption, working hours, and sleeping time (hours/day). Working hours and age group were dichotomized at the median. LS-means: least squares means
    Long working hours and overweight and obesity in working adults
    VariableN (%), Mean ± SD
    Women(N = 411)Men(N = 300)
    General characteristics
     Age group
      40–49220(53.5)141(47)
      50–59123(37.5)111(37)
       ≥ 6057(17.4)48(16)
     Marital status
      Unmarried10(2.5)8(2.7)
      Married367(91.5)277(93.9)
      Divorced/Widow/Widower24(6.0)10(3.4)
     Educational level
      Low200(48.7)129(43)
      Middle191(46.5)136(45.3)
      High20(4.9)35(11.7)
     Household income (US$/Month)
       < 2,00021(5.8)18(6.3)
      2,000–3,00018(5)17(6.0)
       ≥ 3,000321(89.2)249(87.7)
     Smoking
      Non-smoker396(96.3)86(28.7)
      Smoker15(3.7)214(71.3)
     Alcohol consumption
      Non-drinking284(69.1)54(18)
      Drinking127(30.9)246(82)
    Anthropometric characteristics
     BMI(kg/m2)* 23.2 ± 2.924.5 ± 2.7
      Prevalence of overweight(%)+ 102(24.8 %)85(28.3 %)
      Prevalence of obesity(%)+ 97 (23.6 %)134(44.7 %)
     PBF(%)* 27.3 ± 5.323.9 ± 4.5
      Prevalence of overweight(%)+ 156 (38.0 %)115 (38.3 %)
      Prevalence of obesity(%)+ 48 (11.7 %)136(45.3 %)
     Lean body mass(kg)* 36.9 ± 3.548.9 ± 4.5
    BMI (kg/m2)PBF (%)
    WomenMenWomenMen
    VariableControls* Cases+ Controls* Cases+ Controls* Cases+ Controls* Cases+
    (N = 207)(N = 204)(N = 81)(N = 219)(N = 207)(N = 204)(N = 49)(N = 251)
    Age group
     40–49126 (59.4)94 (47.2)34 (42)107 (42)132 (63.8)88 (43.1)25 (51)116 (46.2)
     50–5969 (32.6)79 (39.7)31 (38.3)80 (38.3)67 (32.4)81 (39.7)17 (34.7)94 (37.5)
      ≥ 6017 (8)26 (13.1)16 (19.8)32 (19.8)8 (3.9)35 (17.2)7 (14.3)41 (16.3)
    p = 0.01 p = 0.21 p < 0.0001 p = 0.55
    Marital status
     Unmarried5 (2.4)5 (2.6)3 (3.8)5 (2.3)5 (2.5)5 (2.5)1 (2)7 (2.9)
     Married191 (92.3)176 (90.7)74 (92.5)203 (94.4)187 (92.6)180 (90.5)45 (91.8)232 (94.3)
     Divorced/Widow/Widower11 (5.3)13 (6.7)3 (3.8)7 (3.3)10 (5)14 (7)3 (6.1)7 (2.9)
    p = 0.67 p = 0.79 p = 0.48 p = 0.29
    Educational level
     Low89 (42)111 (55.8)36 (44.4)93 (42.5)89 (43)111 (54.4)23 (46.9)106 (42.2)
     Middle110 (51.9)81 (40.7)40 (49.4)96 (43.8)104 (50.2)87 (42.7)22 (44.9)114 (45.4)
     High13 (6.1)7 (3.5)5 (6.2)30 (13.7)14 (6.8)6 (2.9)4 (8.2)31 (12.4)
    p = 0.005 p = 0.28 p = 0.01 p = 0.40
    Income (US$/Month)
      < 2,00012 (6.6)9 (5.1)4 (5)14 (6.9)11 (6.1)10 (5.6)2 (4.1)16 (6.8)
     2,000-3,0008 (4.4)10 (5.6)5 (6.3)12 (5.9)7 (3.9)11 (6.2)2 (4.1)15 (6.4)
      ≥ 3,000162 (89)159 (89.3)71 (88.8)178 (87.3)163 (90.1)158 (88.3)45 (91.8)204 (86.8)
    p = 0.73 p = 0.63 p = 0.81 p = 0.35
    Smoking
     Non-smoker207 (97.6)189 (95)25 (30.9)61 (27.9)202 (97.6)194 (95.1)15 (30.6)71 (28.3)
     Smoker5 (2.4)10 (5)56 (69.1)158 (72.2)5 (2.4)10 (4.9)34 (69.4)180 (71.7)
    p = 0.24 p = 0.71 p = 0.28 p = 0.88
    Alcohol consumption
     Non-drinking151 (71.2)133 (66.8)14 (17.3)40 (18.3)146 (70.5)138 (67.7)10 (20.4)44 (17.5)
     Drinking61 (28.8)66 (33.2)67 (82.7)179 (81.7)61 (29.5)66 (32.4)39 (79.6)207 (82.5)
    p = 0.39 p = 0.98 p = 0.60 p = 0.78
    Working hours
      < 9 h/day193 (93.7)169 (86.7)47 (58.8)146 (67.6)189 (93.6)173 (86.9)29 (60.4)164 (66.1)
      ≥ 9 h/day13 (6.3)26 (13.3)33 (41.3)70 (32.4)13 (6.4)26 (13.1)19 (39.6)84 (33.9)
    p = 0.03 p = 0.20 p = 0.04 p = 0.55
    Occupational sitting time
      < 4 h/day152 (71.7)132 (66.3)28 (34.6)74 (33.8)149 (72)135 (66.2)14 (28.6)88 (35.1)
      ≥ 4 h/day60 (28.3)67 (33.7)53 (65.4)145 (66.2)58 (28)69 (33.8)35 (71.4)163 (64.9)
    p = 0.28 p = 1.00 p = 0.24 p = 0.48
    Regular exercise
     No89 (42.4)73 (36.9)34 (42.5)84 (38.7)79 (38.5)83 (40.9)19 (38.8)99 (39.9)
     Yes121 (57.6)125 (63.1)46 (57.5)133 (61.3)126 (61.5)120 (59.1)30 (61.2)149 (60.1)
    p = 0.30 p = 0.65 p = 0.70 p = 1.00
    Sleeping hours
      > 9 h/day135 (65.5)146 (75.7)59 (72.8)157 (72)132 (65.4)149 (75.6)35 (71.4)181 (72.4)
        9 h/day71 (34.5)47 (24.4)22 (27.2)61 (28)70 (34.7)48 (24.4)14 (28.6)69 (27.6)
    p = 0.04 p = 1.00 p = 0.03 p = 1.00
    BMI (kg/m2)PBF (%)
    WomenMenWomenMen
    VariableCrude ORAdjusted OR* Crude ORAdjusted OR* Crude ORAdjusted OR* Crude ORAdjusted OR*
    (95 % CI)(95 % CI)(95 % CI)(95 % CI)(95 % CI)(95 % CI)(95 % CI)(95 % CI)
    Socio-demographic factors
     Age group
      40–4911111111
      50–591.541.470.820.661.811.961.191.41
    (1.01–2.33)(0.89–2.42)(0.47–1.45)(0.34–1.28)(1.19–2.76)(1.18–3.24)(0.61–2.34)(0.66–3.02)
      60+2.052.490.640.486.567.371.261.65
    (1.05–4.00)(1.16–5.33)(0.31–1.30)(0.21–1.11)(2.91–14.81)(3.06–17.76)(0.51–3.14)(0.57–4.76)
     Marital status
      Unmarried11111111
      Married0.920.741.651.650.961.410.740.94
    (0.26–3.24)(0.17–3.18)(0.38–7.06)(0.35–7.71)(0.27–3.38)(0.30–6.65)(0.09–6.13)(0.11–8.35)
      Divorced, Widow/Widower1.180.511.40.831.40.750.330.14
    (0.27–5.18)(0.09–2.89)(0.20–10.03)(0.09–7.49)(0.32–6.16)(0.12–4.7)(0.03–4.04)(0.01–2.09)
     Educational level
      Low11111111
      Middle0.590.720.930.870.670.871.121.29
    (0.40–0.88)(0.45–1.16)(0.55–1.58)(0.48–1.59)(0.45–1.00)(0.54–1.41)(0.59–2.14)(0.64–2.61)
      High0.430.202.322.600.340.211.681.80
    (0.17–1.13)(0.05–0.78)(0.84–6.45)(0.81–8.36)(0.13–0.93)(0.05–0.85)(0.54–5.23)(0.54–6.02)
    Income (US$/Month)
      < 2,00011111111
     2,000–3,0001.671.720.690.421.731.630.940.99
    (0.47–5.93)(0.41–7.31)(0.15–3.15)(0.08–2.33)(0.48–6.2)(0.37–7.20)(0.12–7.52)(0.11–9.07)
      ≥ 3,0001.311.290.720.401.070.820.570.41
    (0.54–3.19)(0.48–3.48)(0.23–2.25)(0.10–1.57)(0.44–2.58)(0.30–2.24)(0.13–2.55)(0.08–2.03)
    Lifestyle factors
     Smoking
      Non-smoker11111111
      Smoker2.191.871.161.472.081.861.121.25
    (0.74–6.52)(0.55–6.39)(0.66–2.02)(0.77–2.81)(0.70–6.20)(0.54–6.43)(0.57–2.18)(0.58–2.67)
     Alcohol consumption
      Non-drinking11111111
      Drinking1.231.390.940.911.151.441.211.70
    (0.81–1.87)(0.85–2.25)(0.48–1.83)(0.43–1.96)(0.75–1.74)(0.88–2.37)(0.56–2.60)(0.73–3.93)
     Working hours
       < 9 h/day11111111
       ≥ 9 h/day2.282.420.680.462.192.500.780.63
    (1.14–4.59)(1.05–5.57)(0.40–1.16)(0.24–0.87)(1.09–4.39)(1.07–5.79)(0.41–1.48)(0.30–1.32)
    Occupational sitting time
      < 4 h/day11111111
      ≥ 4 h/day1.290.961.041.161.260.980.850.91
    (0.85–1.96)(0.53–1.76)(0.61–1.77)(0.63–2.12)(0.78–2.06)(0.53–1.83)(0.46–1.57)(0.45–1.85)
     Regular exercise
      No11111111
      Yes1.261.041.171.310.910.810.950.89
    (0.85–1.88)(0.65–1.66)(0.70–1.97)(0.74–2.33)(0.61–1.35)(0.5–1.32)(0.51–1.79)(0.46–1.74)
     Sleeping hours
       > 9 h/day11111111
         9 h/day0.610.661.041.050.610.650.950.79
    (0.40–0.95)(0.40–1.09)(0.59–1.85)(0.56–1.99)(0.39–0.94)(0.39–1.10)(0.48–1.88)(0.39–1.63)
    CategoryN (%)Odds ratios (95 % Confidence Intervals)
    BMIPBF
    CrudeAdjusted* CrudeAdjusted*
    Group1 (Age < 50 and working hours < 9)263 (37.73)1111
    Group2 (Age ≥ 50 and working hours < 9)292 (41.89)1.69(1.11–2.56)1.68(1.04–2.73)2.66(1.67–3.91)2.87(1.75–4.69)
    Group3 (Age < 50 and working hours ≥ 9)87 (12.48)2.39(0.94–6.03)2.34(0.77–7.11)2.60(1.32–8.90)2.73(1.19–12.06)
    Group4 (Age ≥ 50 and working hours ≥ 9)55 (7.89)3.82(1.31–11.14)3.56(1.03–12.37)3.43(1.23–9.54)3.90(1.05–11.00)
    Table 1 Characteristics of study subjects by gendera

    *Values are Mean ± SD

    +Abbreviations. BMI: Body mass index (Cut-off limits of overweight: 23 ≤ BMI (kg/m2) < 25, Cut-off limits of obesity: BMI (kg/m2) ≥25), PBF: Percent body fat (Cut-off limits of overweight: 20 = <PBF (%) < 25 in men and 30 ≤ PBF (%) < 35 in women, Cut-off limits of obesity: men’s PBF (%) ≥ 25; women’s PBF (%) ≥ 35)

    aDifferences between sexes: *P < 0.05 obtained by students t-test, **P < 0.05 obtained by χ 2-test

    Table 2 Prevalence of socioeconomic and lifestyle characteristics for being overweight or obese based on BMI and PBF by gender

    *Controls. BMI: Body mass index (Cut-off limits of overweight: BMI (kg/m2) <25, PBF: Percent body fat (Cut-off limits of overweight: men’s BF (%) < 20; women’s BF (%) < 30)

    +Cases. BMI: Body mass index (Cut-off limits of overweight: BMI (kg/m2) ≥25, PBF: Percent body fat (Cut-off limits of overweight: men’s BF (%) ≥ 20; women’s BF (%) ≥ 3

    Working hours, occupational sitting time and Sleeping time were dichotomized at the median

    Table 3 Odds ratio and 95 % Confidence intervals of overweight or obese based on BMI and PBF by socioeconomic and lifestyle characteristics for women and men

    *Adjusted for confounding factors except for the targeted variable itself. The confounding factors involve age, educational level, smoking, alcohol consumption, working hours, daily occupational sitting time, and sleeping hours (h/day)

    Table 4 Combined effects of age and daily working hours for overweight or obesity based on BMI and PBF criterion in women

    *Adjusted for confounding factors except for the targeted variable itself. The confounding factors involve age, educational level, smoking, alcohol consumption, working hours, daily occupational sitting time, and sleeping hours (h/day). Working hours and age group were dichotomized at the median


    Ann Occup Environ Med : Annals of Occupational and Environmental Medicine
    Close layer
    TOP