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published_or_final_version / Zoology / Master / Master of Philosophy

(Uncorrected OCR) Abstract Many studies have been conducted in Caucasian populations on the optimal body mass index cut-off for obesity, as well as the relationship between body mass index and percentage body fat and their associations with cardiovascular risk factors. However, few studies of this kind have been conducted in the Hong Kong Chinese population, This research is deemed to be important due to ethnic differences between Asians and Caucasians, Therefore, this dissertation aims to determine any ethnic differences from a sample of the local Hong Kong Chinese population, in order to advance health care policies controlling known cardiovascular risk factors. A total of 800 subjects were randomly selected from a pool of subjects participated in a Hong Kong Cardiovascular Risk Factor Prevalence study conducted in 1994-1996. These subjects were contacted and 453 disease-free subjects (210 males and 243 females) consented to participate in the current study, Data collected included serum and blood pressure measurements, body mass index, percentage body fat measured by bioelectrical impedance analysis, and a self-completed cardiovascular risk factor questionnaire, The mean age of the 453 subjects was 51.64 years (SD=12.3). When obesity was defined as percentage body fat ~ 25 and 2: 30 in males and females respectively, 23 kg/m2 was found to be the optimum cut-off value, with 78% correct classification (95% CI = 69%-87%). The corresponding sensitivity and specificity were 88% (95% CI = 81 %-95%) and 67% (95% CI = 57%-77%) respectively. On the other hand, if obesity was defined as percentage body fat ~ 25 and 2: 35 in males and females respectively, then 25 kg/m2 was found to be the best cut-off value with 82% correct classification (95% CI = 74%-90%). The corresponding sensitivity and specificity were 78% (95% CI = 69%-87%) and 85% (95% Cl = 78%-92%) respectively. Moreover, body mass index was found to be quadratically body fat. The quadratic relationship did not appear two genders, except that the percentage body fat of of females by 9.97 (SE=0.33). Finally, except for total cholesterol, high density lipoprotein cholesterol, and fasting glucose, body mass index did not provide any substantial information additional to percentage body fat on serum and blood pressure measurements. was the only measure on which percentage body fat did additional to body mass index. When waist-hip body mass index and percentage body fat,. except for body mass index did not have additional information on measurements when percentage body fat or/and [n conclusion, the optimal body mass index cut-off for obesity in Hong Kong Chinese was lower than the 30kg/m2 recommended by the World Health Organization, a clear reflection of ethnic difference between Asians and Caucasians. The quadratic relationship between percentage body fat and body mass index was similar in Hong Kong Chinese as in Caucasians and Blacks. Moreover, percentage body fat together with waist-hip-ratio were found to be better indicators of cardiovascular risk factors in Hong Kong. This was the first time such findings were found in the Hong Kong Chinese population. II / abstract / toc / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / abstract / Community Medicine / Doctoral / Doctor of Philosophy

Childhood obesity is becoming a challenging issue in China, and parents may playa key role in the development of adolescent obesity. However, the relationships between certain parent-related factors and the development of adolescent obesity are rarely reported in China. Therefore, this study aims to investigate the relationship among Chinese parents' perception of their children's weight, parenting behaviors, parenting style, and adolescents' weight status. Two studies were performed to achieve this purpose. / Key words: adolescent obesity, parenting behaviors, parenting styles / The first study (Chapter 3) examines the validity and reliability of the questionnaires for adolescents and parents; the questionnaires are intended to measure parenting behaviors, parents' perception of their children's weight, and parenting styles in the Chinese context. Several steps were performed. First, the questionnaires were selected based on their validity and reliability, as well as their applicability to the Chinese adolescent and parenting context. Second, the questionnaires were translated into Chinese using a cross-cultural translation technique. Third, five experts were invited to evaluate the content validity and feasibility of the questionnaires for application in the Chinese population. Fourth, 15 pairs of adolescents and their parents were invited to attend a short interview after completing the experimental version of the questionnaires. They were asked to share comments on the readability and cultural relevance of the questionnaire. The questionnaires were then revised according to their feedback. Fifth, 127 pairs of adolescents (10-15 years old) and their parents (Ganzhou: 62 pairs, Shantou: 65 pairs) were recruited to examine the retest reliability and internal consistency of the questionnaires. Sixth, the data collected in the main survey were used to examine construct validity. The result showed that 10 items were excluded because of poor content validity or low intraclass correlation coefficient (<0.7). The internal consistencies of the subscales (ranging from 0.61 to 0.81) were found to be acceptable (Cronbach's alpha >0.6). The goodness-of-fit statistics (RMSEA, CFI, and NNFI) also indicated acceptable fit for the theory models. The results suggest that the validity and reliability of the questionnaires are acceptable, and the questionnaires are applicable to Chinese adolescents and parents in Southern China. / The second study (Chapters 4,5,6) determines the relationships among parenting behaviors, parents' perception of their children's weight, parenting style, and adolescent weight status. A total of 2,143 adolescents and 1,869 parents were recruited from secondary schools in Ganzhou and Shantou in China. The adolescents' weights and heights were measured by trained testers. The dietary habits and physical activity level of the adolescents, as well as parenting behaviors, parenting styles, parents' perception of their children's weight, and demographic information were collected through questionnaires issued to the adolescents and parents validated in Study 1. Several parenting behaviors, including "pressure to eat" and "diet and PA monitoring," were found to be significantly related to adolescents' age and gender-specific BMI Z score (Z-BMI), although the correlation coefficients were low (r ranged from -0.23 to 0.09, p (r ranged from -0.23 to 0.09, p<0.01). The results of the hierarchical multiple regression revealed that "pressure to eat" and "diet and PA monitoring" were the predictors of adolescent Z-BMI. The results of Kappa statistics showed that only a slight agreement exists between parental perception of their children's weights and the adolescents' actual weights (Kappa=0.221, p<0.01). A significant difference in parenting behaviors was found between parents with correct and incorrect perceptions of their children's weight. Compared with the reference authoritative parenting style, the odds of acquiring unhealthy dietary habits were significantly higher for children with authoritarian (Father: OR=1.67, 95%CI: 1.29-2.16; Mother: OR=1.72, 95%CI: 1.31-2.26) and neglectful (Father: OR=2.17, 95%CI: 1.66-2.82; Mother: OR=2.29, 95%CI: 1.76-3.00) parents. The odds of being physically inactive for children with neglectful parents were almost twice than that for children with authoritative parents (Father: OR=2.05, 95%CI: 1.37-3.06; Mother: OR=1.77, 95%CI: 1.18-2.67). Significant differences were found in the parenting behaviors of parents with four different parenting styles. However, no association was found between parenting style and adolescent weight. The data of this study suggest that parenting behaviors are weakly but significantly associated with the development of adolescent obesity. Misclassifications of children's weight status were prevalent among Chinese parents. Parental perceptions of their children's weights were associated with some parenting behaviors related to children's weight development. The adolescents' dietary habits, physical activity, and some parenting behaviors were associated with parenting style. However, there was no direct association between parenting style and adolescent weight. / Wen, Xu. / Adviser: Stanley Sai-Chuen Hui. / Source: Dissertation Abstracts International, Volume: 73-03, Section: A, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves 130-163). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Sea Man Mei. / "September 2004." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (p. 194-218). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest Information and Learning Company, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. Ann Arbor, MI : ProQuest dissertations and theses, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.