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Background Underweight is associated with increased risk of mortality and morbidity. It is reported that the prevalence of underweight is increasing among Korean young women. However, there have been few studies on sociodemographic factors related to being underweight. This study was conducted to elucidate the sociodemographic characteristics of Korean underweight adults. Methods This study is a cross-sectional study of 7,776 adults aged 25 to 69 years using data from the Korea National Health and Nutrition Examination Survey, 2007-2010. Study subjects were composed of underweight and normal-weight adults excluding overweight adults. Body mass index was calculated from measured height and weight. Health behaviors such as smoking, drinking, and physical activity were surveyed through self-administered questionnaires, and socioeconomic status, marital status, and history of morbidity were surveyed through face-to-face interviews. Results Women had a higher frequency of underweight (10.4% vs. 7.0%, P < 0.001) than men. Among men, current smoking (odds ratio [OR], 1.62) and past history of cancer (OR, 2.55) were independently related to underweight. Among women, young age (OR, 2.06), former smoking (OR, 1.69), and being unmarried (OR, 1.56) were identified as independently related factors of underweight. In addition, among both men and women, alcohol drinking (men OR, 0.57; women OR, 0.77) and past history of chronic diseases (men OR, 0.55; women OR, 0.43) were independently related to a lower frequency of underweight. Conclusion We showed that various sociodemographic factors were associated with underweight. It was ascertained that there were differences in the sociodemographic factors related to underweight between Korean men and women.

BACKGROUND Marital status is as an important sociodemographic variable for health studies. We assessed the association between marital status and health behavior in middle-aged Korean adults. METHODS This is a cross-sectional study of 2,522 Korean middle-aged adults (1,049 men, 1,473 women) from the 2010 Korean National Health and Nutrition Examination Survey. The subjects were classified as living with a partner or living without a partner (never married, separated, widowed, and divorced). We assessed the relationship between marital status and five health behaviors (smoking, high-risk alcohol intake, regular exercise, regular breakfast consumption, and undergoing periodic health screening). RESULTS Age, income level, educational level, and occupational classification were all significantly associated with marital status. The risk of undergoing health screening (odds ratio [OR], 0.53; 95% confidence interval [CI], 0.32 to 0.90) and having regular breakfast (OR, 0.50; 95% CI, 0.27 to 0.92) were significantly lower in men living without a partner than with a partner. Women living without a partner had a higher smoking risk (OR, 2.27; 95% CI, 1.09 to 4.73) and a higher risk of high-risk alcohol consumption (OR, 5.33; 95% CI, 1.65 to 17.24) than their counterparts. CONCLUSION Korean middle-aged adults living with partners are more likely to have healthier behavior than living without a partner. The association between marital status and health behaviors differed by sex.

Background While smoking prevalence in Korean men has been decreasing, it is increasing in Korean women. Little is known about women's smoking inequalities in Korea. This study was conducted to investigate the association of socioeconomic indicators with the initiation and cessation of smoking among Korean women. Methods This was a cross-sectional study on 9,089 women aged 25-64 years from the 2008 Seoul Community Health Survey. The data on smoking and socioeconomic status were obtained through face-to-face interviews. Smoking initiation rate was defined as the proportion of the individuals who had started smoking at least one cigarette among all subjects. Smoking cessation rate was calculated by dividing the number of individuals who had quit smoking by the number of ever smokers. Education level, total family income and occupation were investigated as socioeconomic indicators. Results Education level was significantly associated with both initiation and cessation of smoking. Lower educated women had a higher likelihood of smoking initiation (odds ratio [OR], 1.72; 95% confidence interval [CI], 1.17 to 2.51) but lower likelihood of smoking cessation (OR, 0.38; 95% CI, 0.22 to 0.66) than higher educated women. Smoking initiation rate was higher in manual workers (OR, 1.65; 95% CI, 1.20 to 2.27) than in non-manual workers. However, there were no significant differences of both initiation and cessation of smoking according to total household income. Conclusion This study shows that there are smoking inequalities among Korean women. It is thought that education level and occupation are important determinants of women's smoking status.

Background Youth suicide is increasingly being recognized as a major social problem in South Korea. In this study, we aimed to explore the effects of parental support on the relationship between life stress and suicidal ideation among middle-school students. Methods This study analyzed data from a cross-sectional study on mental health conducted by the South Korea National Youth Policy Institute between May and July of 2013. Questionnaire responses from 3,007 middle-school students regarding stress factors, thoughts of suicide during the past year, and parental support were analyzed in terms of 3 subscale elements: emotional, academic, and financial support. Results Among the participants, 234 male students (7.8%) and 476 female students (15.8%) reported experiencing suicidal ideation in the past year. Life stress significantly influenced suicidal ideation (P

Background Adolescent smoking is positively related to weight control attempts, especially by unhealthy methods. The co-occurrence of smoking and unhealthy weight control behaviors may cause serious health problems in adolescents. This study examined the relationship of smoking with unhealthy weight control behaviors among Korean adolescents. Methods This cross-sectional study involved 31,090 students of grades 7 to 12, who had tried to reduce or maintain their weight during the 30 days prior to The Tenth Korea Youth Risk Behavior Web-based Survey, 2014. Data on height, weight, weight control methods, smoking, alcohol intake, living with one's family, and perceived economic status were obtained through self-report questionnaires. 'Unhealthy weight control behaviors' were subcategorized into 'extreme weight control behaviors' and 'less extreme weight control behaviors.' Results The smoking rates were 13.3%±0.4% in boys and 3.8%±0.2% in girls. Current smokers were more likely to engage in extreme weight control behaviors (odds ratio [OR], 1.47; 95% confidence interval [CI], 1.09 to 2.00 in boys, and OR, 2.05; 95% CI, 1.59 to 2.65 in girls) and less extreme weight control behaviors (OR, 1.23; 95% CI, 1.07 to 1.40 in boys, and OR, 1.47; 95% CI, 1.22 to 1.76 in girls) compared to non-smokers among both boys and girls. Conclusion Current smoking is independently related to a high likelihood of engaging in unhealthy weight control behaviors among Korean adolescents. This relationship is stronger for girls than for boys. Extreme weight control behaviors have a stronger relationship with current smoking than less extreme weight control behaviors.

BACKGROUND: This study aimed to determine the prevalence of metabolically healthy and unhealthy obesity (MHO and MUO, respectively) and examine the demographic, anthropometric, and lifestyle predictors of metabolic health status in Korean children and adolescents. METHODS: This study was based on data collected from the Korean Children-Adolescent Study in 2010. A total of 1,700 children (846 boys and 854 girls) were included in the primary cohort and classified into metabolically healthy and unhealthy groups according to factors related to the metabolic syndrome. Demographic and biochemical features were evaluated in study participants. Logistic regression estimated the odds ratios of having more fat mass among MUO compared with MHO children after adjusting for confounding factors. RESULTS: Mean body mass index was higher in the MUO group than in the MHO group (24.83 vs. 23.02 kg/m(2), respectively). The proportion of obese participants was also higher in the MUO group (59.4%) than in the MHO group (20.7%). MHO children were more likely to have parents with better socioeconomic status and a higher fruit and vegetable intake compared with MUO children. Higher fat mass and percent fat was associated with MUO according to multiple logistic regression analysis. CONCLUSION: Fat mass and percent fat are associated with metabolically healthy phenotypes of obesity among children and adolescents.

Ba ckground: Korean women are known to have a very low smoking rate. However, the actual smoking rate among Korean women is higher than 10% and may continue to increase gradually. In addition, some Korean women use extreme weight control methods that have potentially harmful effects. This study was conducted to elucidate weight control methods related to cotinine-verified smoking among Korean adult women. Me thods: This cross-sectional study involved 4,189 women aged ≥19 years who had attempted weight control during the past 1 year from the Korea National Health and Nutrition Examination Survey, 2008–2011. Smoking status was assessed using both self-report questionnaires and assays of urinary cotinine, and weight control methods were investigated using self-report questionnaires. Re sults: The smoking rate based on the measurement of urinary cotinine was 12.4% ± 0.8% among Korean women. Cotinine-verified smokers were more likely to attempt fasting (odds ratio, 2.19; 95% confidence intervals, 1.03 to 4.67), taking prescription diet-pills (odds ratio, 2.37; 95% confidence intervals, 1.47 to 3.82), and taking nonprescription diet-pills (odds ratio, 3.46; 95% confidence intervals, 1.71 to 6.98), and were less likely to attempt eating less food or modifying dietary patterns (odds ratio, 0.71; 95% confidence intervals, 0.51 to 0.99) compared to non-smokers. Co nclusion: Korean adult women’s smoking is independently related to a high likelihood of using weight control methods with potentially harmful effects, such as fasting and taking diet-pills, and a low likelihood of choosing weight control methods, including dietary modification, that require constant effort for a prolonged time.

Background With metabolic syndrome (MS) being a major risk factor for cardiovascular disease, and central obesity being a major predisposing factor for MS, intensive research is currently being performed on cutoff values according to race and sex. Menopause is an especially significant factor in designating cutoff values for female central obesity, as menopause brings sudden bodily changes that induce central obesity and increased prevalence of MS. Therefore this study aimed to investigate the cutoff values for the obesity index and its validity in predicting the criteria for MS in Korean women according to menstrual status. Methods The study focused on 3,103 women 20 years of age or older participating in the 2007 Korea National Health and Nutrition Examination Survey. Definitions of non-adipose components of MS were defined by the International Diabetes Federation, and menstrual status was judged on the basis of survey results. The sensitivity, specificity, and positive and negative predictive values of the central obesity index (body mass index [BMI], waist circumference [WC], waist-to-height ratio [WHtR]) according to menstrual status for two or more non-adipose components of MS were calculated based on the Youden index. Results Area under the curve (AUC) values predicting the presence of two or more metabolic risk factors were higher in pre-menopausal women, with AUC values for BMI, WC, and WHtR being, in pre- and post-menopausal women, 23.1 kg/m(2) vs. 23.9 kg/m(2), 76.1 cm vs. 82.5 cm, and 0.49 vs. 0.53, respectively. The WC cut off (76 cm) for pre-menopausal women was found to be more sensitive and more effective at screening for MS risks than the cutoff value given by the Korea Society for the Study of Obesity. Conclusion The central obesity index showed better predictability for MS risk in pre-menopausal women. Because the central obesity index cutoff values are lower in pre-menopausal women, the possibility of metabolic risk can be considered for pre-menopausal women with WC lower than 85 cm. Assessment and control of other risks are needed accordingly for preventing the development of MS.

Background Underweight refers to the weight range in which health risk can increase, since the weight is lower than a healthy weight. Negative attitudes towards obesity and socio-cultural preference for thinness could induce even underweight persons to attempt weight control. This study was conducted to investigate factors related to weight control attempts in underweight Korean adults. Methods This was a cross-sectional study on 690 underweight adults aged 25 to 69 years using data from the Korea National Health and Nutrition Examination Survey, 2007-2010. Body image perception, weight control attempts during the past one year, various health behaviors, history of chronic diseases, and socioeconomic status were surveyed. Results Underweight women had a higher rate of weight control attempts than underweight men (25.4% vs. 8.1%, P < 0.001). Among underweight men, subjects with the highest physical activity level (odds ratio [OR], 7.75), subjects with physician-diagnosed history of chronic diseases (OR, 7.70), and subjects with non-manual jobs or other jobs (OR, 6.22; 12.39 with reference to manual workers) had a higher likelihood of weight control attempts. Among underweight women, subjects who did not perceive themselves as thin (OR, 4.71), subjects with the highest household income level (OR, 2.61), and unmarried subjects (OR, 2.08) had a higher likelihood of weight control attempts. Conclusion This study shows that numbers of underweight Korean adults have tried to control weight, especially women. Seeing that there are gender differences in factors related to weight control attempts in underweight adults, gender should be considered in helping underweight adults to maintain a healthy weight.

Background: This preliminary study is to assess risk factors associated with children’s body mass index (BMI) and their changes over a 2-year period based on the analysis of the Obesity and Metabolic Disorders Cohort in Childhood registry. Methods: A total of 1,504 children comprised of 474 1st graders and 1,030 4th graders were included in the study. Data on physical activity, dietary intake, and socioeconomic status were obtained through self-administered questionnaires, and height and weight were measured annually for 2 years. Results: In a cross-sectional analysis, BMI of 1st graders was associated with higher parental BMI (both P < 0.001) and frequent snack consumption (P = 0.049). BMI of 4th graders was additionally associated with shorter sleep duration (P = 0.001), lower household income (P = 0.016), higher fat intake (P = 0.017), and frequent meal skipping (P = 0.020). During a 2-year follow-up, BMI increased by 0.8 ± 1.4 kg/m 2 in 1st graders and by 1.3 ± 1.4 kg/m 2 in 4th graders. In a longitudinal analysis, higher exercise frequency (P = 0.007), shorter sleep duration (P = 0.027), lower household income (P = 0.002), and higher paternal BMI (P = 0.002, 0.043) were signifi cant predictors of BMI changes in the 1st graders whereas only higher maternal BMI (P=0.035), and frequent snack consumption (P = 0.010) were predictors for the 4th graders BMI changes. Conclusion: Our findings indicate that parental obesity, short sleep duration, low socioeconomic status, and frequent snacking are associated with BMI and BMI changes.

Background: Obesity is a disease state which should be prevented and managed. However, attempting unhealthy weight control can be related to psychologic problem like depression. This study was conducted to investigate the relationship between weight control methods and the depressive symptom among adults who have had weight control experience within recent 1 year. Methods: This study is a cross-sectional study on 10,285 adults (age, 25 to 69 years), who had weight control experience within recent 1 year, from the Community Health Survey, Seoul, 2009. Depressive symptom, tried weight control methods, weight, height, smoking status, alcohol intake and socioeconomic status were surveyed through face-to-face interview. The Center for Epidemiological Studies-Depression Scale is used for assessment of depressive symptom. Results: Depressive symptom was diagnosed in 5.2% (male: 2.9%, female: 7.0%) of study subjects and the most frequent method for weight control within 1 year was exercise (77.9%). Among men, depressive symptom was related to high likelihood of trying one-food diet (odds ratio [OR], 3.27; 95% confidence interval [CI], 1.62 to 6.62), fasting (OR, 3.59; 95% CI, 1.61 to 8.02), dietary supplements (OR, 2.57; 95% CI, 1.40 to 4.73), Korean herbal medicine (OR, 2.85; 95% CI, 1.24 to 6.51), self-medication (OR, 5.50; 95% CI, 1.53 to 19.80). Among women, depressive symptom have relationship with high likelihood of trying one-food diet (OR, 1.83; 95% CI, 1.14 to 2.94), fasting (OR, 1.69; 95% CI, 1.10 to 2.59), prescribed medicine (OR, 2.28; 95% CI, 1.48 to 3.52) and low likelihood of trying exercise (OR, 0.65; 95% CI, 0.51 to 0.83). Conclusion: This study shows the difference of tried weight control methods depending on depressive symptom. Depressive symptom was related to high likelihood of trying weight control methods such as one-food diet, fasting and taking a diet-pill. In addition, that symptom was also related to low likelihood of trying exercise in women.

BACKGROUND: Obesity increases the risk of many chronic diseases and contributes to functional disabilities. We assessed the relationship among obesity and obesity related chronic disease and disability in Korean adults. METHODS: This study used data from the 2005 Korean National Health and Nutrition Examination Survey. A total of 5,462 persons (2,325 men, 3,137 women) aged 20 years and older were included in this analysis. Obesity was measured by body mass index and abdominal obesity was by waist circumference. Information on the presence of chronic diseases was based on the self-report of having been diagnosed by physicians. Functional disability was assessed using the Korean activities of daily living (K-ADL) and the Korean instrumental ADL (K-IADL) scales. RESULTS: The relationship between obesity and prevalence of obesity-related chronic diseases was higher in the older aged group (>60 years for men, >70 years for women) than in the younger aged group. Waist circumference was more related to a higher prevalence of chronic diseases than body mass index in the younger aged group. Abdominal obesity increased the risk (odds ratio, 2.59; 95% confidence interval, 1.19 to 5.66) of having limitation in activities of daily living for the younger aged men after adjustments for age, smoking status, presence of chronic diseases, and body mass index. Body mass index was not associated with disability in either men or women. CONCLUSION: The association between obesity and prevalence of chronic disease differed depending on age and sex. It is important to control abdominal obesity to prevent disability in younger aged men.

Background High density lipoprotein (HDL) cholesterol level varies with ethnicity and gender. In Korea there has not been an agreement on standards for HDL cholesterol level. Therefore, in order to establish a foundation for research on HDL cholesterol, we investigated the gender difference in HDL cholesterol level after adjusting associated factors. Methods The study population included 4,465 individuals (1,833 men, 2,632 women) representing 33,502,918 Koreans 20 years of age or older, who participated in the 2005 Korean National Health and Nutrition Survey. After stratifying by gender, we analyzed the HDL cholesterol level according to the general characteristics of the study population. Then we identified independent factors associated with HDL cholesterol level. After adjusting for covariates, we estimated the gender difference in HDL cholesterol level. Results We demonstrated that age, current smoking, body mass index, alcohol intake, triglyceride and low density lipoprotein cholesterol level have significant impact on HDL cholesterol level. In addition, educational status was also an important factor for men, while fat intake was a significant factor for women. After adjusting associated factors, the means (standard errors) of HDL cholesterol level were 43.8 (0.2) mg/dL in men and 46.3 (0.2) mg/dL in women, respectively. Conclusion The mean gender difference in HDL level (2.5 mg/dL) in Korean adults was, therefore, less than those observed in previous western studies.

Background: Breakfast consumption is related not only with foods and nutrients intake, but also obesity, chronic diseases, school performance, and cognitive function. This study is to assess factors associated with breakfast skipping and its effects on food and nutrients intake in 5th grade children from the obesity and metabolic disorders cohort. Methods: BMI percentile was used as an obesity index. Overnight fasting blood was collected to measure blood lipids, and glucose level. Dietary habits and physical activity levels were assessed with a self-filled questionnaire. If a student said "yes" to the question, "Have you taken all breakfast during previous seven days?," he or she was considered as 'breakfast consumer,' if a respondent said "no," he or she was considered as 'breakfast skipper.' Nutrients intake was estimated from a three-day 24-hour recall including two weekdays and one weekend. Results: Among 1,536 students, 30.1% (n = 235) of boys and 31.3% (n = 231) of girls were the breakfast skipper. The breakfast skippers were more obese (P = 0.011), from families with lower household income (P = 0.037), went to bed late (P = 0.001), had a longer screen time (P = 0.003) than breakfast consumers. All macronutrients intake and the adequacy of micronutrients (iron, zinc, vitamin B1, vitamin B2, vitamin B6, vitamin C, niacin, and folate) intake were lower in breakfast skipper. Conclusion: The breakfast skipping was associated with a lower socioeconomic state and a longer screen time. We confirmed breakfast skipping is a risk factor of nutrients deficiency (quantity) and is also related with food intake quality.

Background: It has been reported that the abdominal obesity can cause various metabolic abnormalities not only in adults but also in adolescents. This study was conducted to investigate lifestyle habits related to abdominal obesity in Korean adolescents. Methods: This study is a cross-sectional study on 561 adolescents (305 boys and 256 girls) aged 12-18 years from the Korean National Health and Nutrition Examination Survey 2005. The abdominal obesity was defined as waist circumference at or above the 90th percentile for each age and gender based on the 2007 growth chart for Korean children. The frequency of physical activity, screen time, and the intake amount of energy and macronutrients were investigated as lifestyle habits. Results: The prevalence of abdominal obesity in Korean adolescents aged 12-18 years was 9.1% (Boys, 9.4%; Girls, 8.7%). The mean of daily screen time was 4.3 ± 0.1 hours (Boys, 4.4 ± 0.2 hours; Girls, 4.2 ± 0.2 hours). The subjects with daily screen time ≥ 5 hours had a 3.0 times increased risk of abdominal obesity compared to subjects with daily screen time < 3 hours (P-value = 0.004). The adjusted odds ratio of fat intake ≥ 35% of energy was 2.57 (95% confidence interval, 1.16 to 5.68; P-value = 0.020) with fat intake < 25% of energy as reference. The relationship between long screen time and abdominal obesity was observed in girls and high fat intake was related to abdominal obesity in boys. Conclusion: This study shows that abdominal obesity in Korean adolescents is associated to long screen time and high fat intake.

Background: Dietary supplements affect the health and disease status of Koreans. We assessed the patterns of dietary supplements use and the related factors in Korean adults from the 2005 Korea National Health and Nutrition Survey (KNHANES). Methods: Among the subjects, 2,024 men and 2,811 women underwent all the three parts of 2005 KNHANES, which consisted the health survey, the health examination, and the nutritional survey. Reported supplements were classifi ed according to the 2008 Korea Food and Drug Administration Notification. We assessed the relationship between supplements use and socioeconomic state, health behaviors, and chronic diseases. Results: Twenty-nine percent of Korean adults was taking dietary supplements. Vitamin/mineral supplements were the most commonly taken one. Glucosamine/mucopolysaccharide, ginseng, spirulina/chlorella, omega-3, and aloe followed in listing. Supplement users were likely to be woman and middle-aged. Supplement use was associated with older, high income, with spouse, higher education, urban-living, regular exercise, non-smoker, and lower BMI. Musculoskeletal diseases were associated with supplement use. Conclusion: Dietary supplement use is prevalent in Korean adults. The supplement use was associated with some demographics characteristics, health behavior, and chronic diseases. These factors should be considered when evaluating the effi cacy of dietary supplements.

Background: Many children and adolescents are exposed to the risk of cardiovascular diseases because of increase in obesity and obesity-related metabolic derangements in children and adolescents. The diagnosis of the metabolic syndrome is useful to identify these children with high cardiovascular risk. In 2007, the International Diabetes Federation (IDF) presented a new defi nition of the metabolic syndrome for children and adolescents. The aim of this study was to estimate the prevalence of the metabolic syndrome using the IDF pediatric defi nition in Korean children and adolescents. Methods: We used data from 931 participants aged 10-19 years in the Korean National Health and Nutrition Examination Survey 2005. The metabolic syndrome was diagnosed by the new IDF pediatric defi nition. Results: The prevalence of the metabolic syndrome in Korean children and adolescents aged 10-19 years was 2.0 ± 0.5% (boys: 3.1 ± 0.8%, girls: 0.8 ± 0.4%). Approximately 95% of children and adolescents with the metabolic syndrome was classifi ed with obesity and none of the normal-weighted participants were diagnosed with the metabolic syndrome. Conclusion: The prevalence of the metabolic syndrome in Korean children and adolescents was 2.0 ± 0.5%. It is expected that the new IDF pediatric defi nition will help to detect children with high cardiovascular risk early and to manage them properly. However, whether the IDF pediatric defi nition of the metabolic syndrome and cut-off points of its components are appropriate for Korean children and adolescents should be answered through future research.