Thesis (PhD)--Stellenbosch University, 2012. / Includes bibliography / ENGLISH ABSTRACT: Background/Aims: Obesity has increased rapidly in South African children and adolescents with significant variability observed among racial groups. Genes that regulate appetite have been studied in different populations worldwide, but their role in obesity among South African adolescents is unknown. The present study aimed at investigating the role of these genes, and their combined effect with physical activity in the development of obesity among South African adolescents. Methods: A total of 1564 South African school learners of Caucasian (n= 146), Mixed Ancestry (n= 872) and Black African (n= 537) ethnic groups were recruited for a research project that aimed to elucidate diabetes and the metabolic syndrome in children and adolescents attending schools in periurban areas of the Western Cape. The present case-control study included 227 obese-overweight (115 Black Africans and 112 Mixed Ancestry), and 204 normal weight (94 Black Africans and 110 Mixed Ancestry) adolescents learners. The learners were genotyped for nine polymorphisms (LEP: 19G>A, Lys36Arg, Val94Met; LEPR: Lys109Arg; Gln223Arg, Lys656Asn; CART: c.160-33G>A, c.499delA, and c.517A>G; GHRL: Leu72Met; and MC3R: Thr6Lys, Val81Ile) using allele-specific restriction enzyme analysis and automated sequencing. Genotype and haplotype associations with anthropometric variables such as body mass index (BMI), waist, hip, and mid-upper-arm circumferences (WC, HC, MUAC), and metabolic traits (fasting blood glucose, high density lipoproteincholesterol, total cholesterol), and blood pressure were further conducted. Furthermore, the type and frequency of physical activity was assessed by means of structured questionnaires; and its effect on obesity-related variables investigated in learners that were genotyped for the MC3R Thr6Lys and Val81Ile polymorphisms. Results: In a stepwise backward logistic regression analysis (containing age, gender, and LEP, LEPR, CART and GHRL polymorphisms), CART c.517A>G was independently significantly associated with obesity (OR= 5.98; 95%CI= 2.02, 21.27). CART c.517G carriers had higher MUAC (b coefficient= 1.88; 95%CI= 0.31, 3.44) while the LEPR 109Arg allele was significantly associated with decreased BMI (b coefficient = -2.36; 95%CI= -4.24, -0.47), WC (b coefficient = -5.66; 95%CI= -9.89, -1.44) and MUAC (b coefficient = -1.61; 95%CI= -3.00, -0.22); after adjusting for age, gender, and ethnicity. The haplotype containing the three LEP polymorphisms (A-A-A compared to the reference G-A-G haplotype) increased BMI (p= 0.0155), MUAC (p= 0.0146), and HC (p= 0.0128). The minor alleles of the MC3R polymorphisms decreased BMI, HC, WC, MUAC and TC; whilst only the Thr6Lys was associated with systolic and diastolic blood pressure (p= 0.0047 and 0.0027, respectively) in Mixed Ancestry learners. Doing house chores was associated with lower total cholesterol, independently and in the presence of the 81Ile allele (b coefficient = -0.355; 95%CI= 0.148, 0.561). Conclusion: To our knowledge, this is the first study that reports CART c.517A>G polymorphism as a risk factor for obesity in adolescents. Furthermore, the present study demonstrated that the MC3R polymorphisms had a positive effect on total cholesterol, which was further enhanced in physically active individuals. Similar to other studies, LEPR Lys109Arg and LEP polymorphisms were associated with variations in obesity-related variables among Black African and Mixed Ancestry South African learners. / AFRIKAANSE OPSOMMING: Agtergrond/Doelwitte: Vetsug het drasties toegeneem in Suid-Afrikaanse kinders en adelossente met ‘n beduidende variasie opgemerk tussen verskillende rassegroepe. Gene verantwoordelik vir regulering van eetlus is reeds wêreldwyd in verskillende bevolkingsgroepe bestudeer, maar hul rol in oorgewig Suid-Afrikaanse adolessente is onbekend. Die huidige studie was daarop gerig om ondersoek in te stel na die rol van hierdie gene en hul gekombineerde effek met fisiese aktiwiteit in die ontwikkeling van vetsug onder Suid-Afrikaanse adolessente. Metodes: ‘n Totaal van 1564 Suid-Afrikaanse leerders van Kaukasiese Afkoms (n=146), Gemengde Afkoms (n=872) en Swart Afkoms (n= 537) was gewerf in die navorsingsprojek wat ten doel gehad het om kinders en adolosente met diabetes en die metaboliese sindroom te identifiseer wat skole bygewoon het in semi-voorstedelike gebiede van die Wes-Kaap. Die huidige gevalle studie het 227 vetsugtige-oorgewig (115 Swart Afkoms en 110 Gemengde Afkoms) en 204 normale gewig (94 Swart Afkoms en 110 Gemengde Afkoms) leerders ingesluit. Die leerders was gegenotipeer vir nege polimorfismes (LEP: 19G>A, Lys36Arg, Val94Met; LEPR: Lys109Arg; Gln223Arg, Lys656Asn; CART: c.160-33G>A, c.499delA, and c.517A>G; GHRL: Leu72Met; and MC3R: Thr6Lys, Val81Ile) met die gebruik van alleel-spesifieke restriksie ensiem analises en geoutomatiseerde DNA volgorde bepalings tegnieke. Genotipiese en haplotipiese assosiasies met antropometriese veranderlikes soos liggaamsmassa indeks (BMI), middel-, heup- en mid-boarm omtrek (WC, HC, MUAC), metaboliese tendense (vastende bloed glukose, hoë-digtheid lipoproteïen-cholesterol, totale cholesterol) en bloeddruk was ook uitgevoer. Die tipe en frekwensie fisiese aktiwiteit was geassesseer deur middel van gestruktureerde vraelyste; en die uitwerking daarvan op vetsugverwante veranderlikes ondersoek in leerders wat vir die MC3R Thr6Lys en Val81Ile polimorfismes gegenotipeer was. Resultate: Statistiese ontleding (‘‘stepwise backward logistic regression analysis”), wat ouderdom, geslag en polimorfismes (LEP, LEPR, CART GHRL) ingesluit het, het getoon dat CART c.517A>G betekenisvol onafhanklik geassosiasieer was met vetsug (OR= 5.98; 95% CI= 2.02, 21.27). CART c.517G draers het ‘n hoër MUAC waarde gehad (b koeffisient = 1.88; 95%CI= 0.31, 3.44), terwyl die LEPR 109Arg alleel betekenisvol geassosieer was met verlaagde BMI ((b koeffisient = -2.36; 95%CI= -4.24, -0.47), WC (b koeffisient = -5.66; 95%CI= -9.89, -1.44) en MUAC (b koeffisient = -1.61; 95%CI= -3.00, -0.22) na die aanpassing van ouderdom, geslag en etnisiteit. Die haplotipe met die drie LEP polimorfismes (A-A-A teenoor die G-A-G verwysingshaplotipe) het die BMI (p= 0.0155), MUAC (p= 0.0146) en HC (p= 0.0128) verhoog. Die mindere allele van die MC3R polimorfismes het die BMI, HC, WC, MUAC en TC verlaag; terwyl slegs die Thr6Lys polymorfisme met sistolies en diastolies bloeddruk (p= 0.0047 en p= 0.0027, onderskeidelik) geassosieer was in Gemengde Afkoms leerders. Die verrigting van algemene huistake was geassosieer met laer totale kolesterol vlakke, onafhanklik en in die teenwoordigheid van die 81lle alleel (b koeffisient= -0.355; 95%CI= 0.148, 0.561). Gevolgtrekking: Na ons wete is hierdie die eerste studie wat die CART c.517A>G polimorfisme as ‘n risikofaktor vir vetsug in adolessente aantoon. Die huidige studie toon ook dat die MC3R polimorfisme ‘n positiewe effek op totale kolesterol gehad het, wat ook verder versterk was in fisiese aktiewe individue. Soortgelyk aan ander studies, was die LEPR Lys109Arg en LEP polimorfismes geassosieer met variasies in vetsug-verwante veranderlikes onder Suid-Afrikaanse Swart en Gemengde Afkoms leerders. / This research was supported by a grant from the University Research Fund of the Cape Peninsula University of Technology, Harry Crossley, University of Stellenbosch, Faculty of Health Sciences, Medical Research Council, and the National Health Laboratory Services, South Africa.

This research study investigates the impact of being obese on all the facets of psychological well-being of the adolescent learner. Definitions for adolescence, obesity and psychological well-being are provided. For the purpose of this study an adolescent is considered to be a scholar between 12 and 18 years. The various methods of measuring obesity are presented and briefly discussed. Body Mass Index is internationally the most commonly used indicator of obesity and was therefore applied by the researcher. The possible causes of obesity are also discussed in this study. Presently there is no accepted standardised definition of psychological well-being, which it was found involves different aspects for different people. This phenomenon varies within various circumstances, is multifaceted in character and is not static. The researcher made use of projection media, expression media, interviews and standardised media to obtain relevant information. The main conclusion is that body image and physical appearance as experienced by an obese adolescent do have a negative impact on the individual's psychological well-being. / Educational Studies / M.Ed.(Specialisation in Guidance and Counselling)

Physical inactivity is one of the major public health problems in many parts of the World. In Scotland it is reported that two thirds of Scottish adults (>16yrs) and one third of Scottish children (<16yrs) do not do sufficient physical activity to gain the health benefits of physical activity. Furthermore, there is still much debate about the nature and volume of physical activity required to provide health benefits. Therefore, more investigations are required to help improve our understanding of the links between physical activity, obesity and health. In addition, the assessment of habitual physical activity needs to be accurately quantified using appropriate methods that are valid and reliable. The main aims of this thesis were thus to assess the validity and reliability of three new generations of movement sensing devices (Actigraph, ActivPAL and SenseWear PRO2) in adults and adolescents in a controlled laboratory environment and to then use the most valid and reliable device in assessing the habitual physical activity of adults (lean and overweigh/obese) and adolescents in a free-living situation. Following objectively assessing the habitual physical activity, investigation of the associations between physical activity status and cardiovascular and metabolic disease risk markers in adults and adolescents were the last main aims of this thesis. In the first study, the results indicated that the new generations of the three devices were reliable in assessing EE during walking on the flat and on a 5% incline in lean and overweight/obese adults and lean adolescents. However, none iii of these devices and the methods or programme versions that were selected and applied was able to accurately estimate EE during walking on a treadmill. However, based on the sensitivity data obtained and previous evidence, the Actigraph was considered the most appropriate device for assessing the habitual physical activity due to its ability to discriminate between physical activity intensities. The second and third studies concluded that adults (including lean and overweight/obese) met the recommended physical activity guidelines for health and wellbeing purposes. However, the data suggest that overweight/obese participants may need to be advised to spend more time in MVPA and probably more vigorous activity to not only reduce body fat but also to increase cardiorespiratory fitness and reduce their chances of future cardiovascular and metabolic disease. The fourth and fifth studies, demonstrated that the Scottish adolescents –in the cross sectional study- were below the recommended physical activity guidelines. When the method of physical activity assessment was adjusted the Scottish adolescents were similar to the adolescents in other European countries and were observed to be more active than adolescents in some of the developed countries such as American adolescents (Texas State). In the case of lean adolescents who have a low physical activity- but who are not sedentary- the cardiovascular and metabolic disease risk markers may not be obvious at this stage, but the differences in glucose and HOMA-IR suggest that there may be early signs of progression towards metabolic disease in this group. iv The importance of the associations between vigorous physical activity and body fat, as well as between body fat and the risk markers of metabolic disease, suggests that future intervention studies should focus on monitoring the outcome from vigorous physical activity interventions vs. moderate activity within current guidelines.

[Truncated abstract] Regular engagement in physical activity is proven to decrease the risk of numerous chronic diseases and to improve mental well-being. However, many children and adults around the world fail to engage in sufficient levels of activity required to produce health benefits, with reports showing physical activity levels still on the decline. Perhaps because of this increase in sedentary lifestyles, obesity has become one of the biggest public health threats in the 21st century. Furthermore, both obesity and physical inactivity are closely related to psychological health, and may play an important role in shaping self-perceptions and feeling of general well-being. '...' In the first study, physical status, physical activity levels, and social physique anxiety measures were obtained from an adolescent sample of 259 participants. Partial correlation analyses revealed that physical activity involvement was not directly linked with physical status; however, both factors were significantly associated with social physique anxiety, which suggested evidence of an indirect link between the two constructs. That is, analyses showed that poor physical status was associated with higher levels of physique anxiety, which in turn linked to low engagement in physical activity. In addition, age and gender effects emerged, revealing unique differences in the ways in which these three variables may be related. To cross-validate and further examine these relationships STUDY 2 extended the range of self-perception measures to include a multidimensional assessment of physical self-concept and a global self-esteem measure along with physique anxiety. These variables were assessed in a German adult sample (N = 229), again alongside measures of physical status and physical activity involvement. Consistent with STUDY 1, no direct link was found between physical status and levels of physical activity involvement. However, evidence of an indirect link did emerge as both variables were related to multiple dimensions of physical self-concept, thereby reinforcing and extending the findings from STUDY 1. Furthermore, age effects emerged for physical self-concept, which had not been confirmed in previous research on physical self-concept. STUDY 3 employed a longitudinal design and investigated changes in physical self-concept, global self-esteem and social physique anxiety before, during, and after participation in a 12-week weight management programme. Participants (N = 63) were assigned to one of three conditions: (1) cognitive-behavioural treatment only, (2) cognitive-behavioural treatment and exercise, and (3) non-treatment control. Statistical analyses revealed a small, but significant reduction in weight for members of both treatment groups. Relative to controls, both treatment groups also improved on a variety of physical self-concept dimensions. At the same time, however, significant group main effects suggested that a weight-loss program incorporating exercise involvement may provide physical self-concept benefits that go beyond those obtained with standard CBT regimes. Collectively, these studies add to the growing body of literature on the connections between physical activity, self-perceptions and physical status. They also highlight the importance of involvement in habitual physical activity throughout the lifespan. Findings are discussed with regards to their contribution to the extant literature, and applied implications, limitations, and future directions are considered.

[Truncated abstract] This descriptive study identified correlates of electronic media use among pre-adolescent children (10-12 year olds). It specifically focused on the potential influence of individual factors and the social and physical environment within the family home setting. The prevalence of overweight/obesity in children is escalating. Sedentary behaviour in the form of electronic media use (comprised of television (TV) and video/DVD viewing, video and computer gaming, and computer use) is a contributing and a modifiable risk factor for overweight/obesity. To date, research focused on sedentary behaviour has been largely derived from physical (in)activity data where the absence or observed low levels of physical activity participation or TV viewing only has been used as a proxy for sedentariness. Little is known about the specificities of children's electronic media use; its impact on children's overall leisure and screen-time; and, the potential influencing factors that may operate at the home level. The family home is a context-specific setting where electronic media use is a daily practice for most children. To better understand electronic-based sedentary behaviour among children the following specific aims were addressed; 1) To describe children's leisure time, particularly time spent with electronic media. 2) To explore children and parents' perceptions about electronic-based sedentary behaviour. 3) To determine the prevalence of children's electronic-media use at home. 4) To examine the influence of individual, family social and home physical factors associated with different levels of electronic media use by children. ... The availability and accessibility of a variety of electronic equipment at home, especially in the child's bedroom (particularly among boys), was also associated with children's screen behaviour. Physical aspects of the family home (i.e., lay-out and yard size) had a mixed effect on children's electronic media use. Overall, the nature of electronic media use among children is complex and is influenced by dimensions that present at children's individual, family social and physical home level. The knowledge generated from this study about specific correlates of electronic media use has extended the understanding about its impact on children's discretionary time. Future prospective longitudinal research is warranted given that most studies investigating electronic media and sedentary behaviour are of cross-sectional design. Including other forms of sedentary behaviour such as sitting and talking with friends and family, reading and/or using telephones may provide a more comprehensive measure of sedentariness in the future. Further studies should use multivariate statistical analyses (i.e., modelling) to improve clarity of relationships between multiple variables and gauge mediating factors. This study also calls for future intervention research. Findings on gender-specific correlates of electronic media use provide superior information for the development of tailored behaviour modification strategies aimed at girls and boys respectively. Active involvement of household members in the intervention is also warranted. Utilising this study's findings may strengthen intervention outcomes towards a more directed and sustained behaviour change

This research study investigates the impact of being obese on all the facets of psychological well-being of the adolescent learner. Definitions for adolescence, obesity and psychological well-being are provided. For the purpose of this study an adolescent is considered to be a scholar between 12 and 18 years. The various methods of measuring obesity are presented and briefly discussed. Body Mass Index is internationally the most commonly used indicator of obesity and was therefore applied by the researcher. The possible causes of obesity are also discussed in this study. Presently there is no accepted standardised definition of psychological well-being, which it was found involves different aspects for different people. This phenomenon varies within various circumstances, is multifaceted in character and is not static. The researcher made use of projection media, expression media, interviews and standardised media to obtain relevant information. The main conclusion is that body image and physical appearance as experienced by an obese adolescent do have a negative impact on the individual's psychological well-being. / Educational Studies / M.Ed.(Specialisation in Guidance and Counselling)

Thesis (MTech (Biomedical Technology))--Peninsula Technikon, 2004. / The prevalence of obesity amongst both the adult and paediatric population has assumed almost epidemic proportions in many developed and developing countries. A recent study by the Medical Research Council found that a disturbing 20% of all South African children could be categorized as being obese. Limited data is currently available on the prevalence of obesity in South African children, particularly from the previously disadvantaged population. Given the global epidemic of paediatric obesity, hypertension and type-2-diabetes and the limited available data relating to obese South African children, further studies to enhance the understanding of the risk factors associated with the epidemic are imperative.

Chan, Po Tai. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 128-150). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese; some appendixes in Chinese.

Made available in DSpace on 2017-06-01T18:08:53Z (GMT). No. of bitstreams: 1 silvana_maria_barros_santos.pdf: 1040372 bytes, checksum: 535cf6f879a0fe744c32c78db0ded9a9 (MD5) Previous issue date: 2013-10-16 / Nowadays, obesity is characterized as a disease of multiple causes, it´s a serious illness and with high incidence in developed and developing countries. This way, it is possible to consider that obesity can be analyzed by various multifactorial features as genetic, social, and affective. In this sense, this dissertation says some affective aspects in obesity and overweight s problematic in adolescent women, seeking to verify possible failures in affective relation mother and daughter, in the early stages of development of the girl. This study, is based on theoretical conceptions of Winnicott (1983, 2000, 2005, 2006), Levinsky (1995), Barbosa Silva (2005), Bruno (2011) and Cardoso (2008). It was used as methodological procedure the qualitative approach of Oral Life History that privileges the narratives of the subject as knowledge their affective experiences. Thus, they have been recorded interviews with obese adolescents or overweight 13 to 18 years who are part of the screening or are in the nutritional treatment Clinic-School of Nutrition of Biological Sciences and Health College (Cesmac) in Maceió, Alagoas. In this way, the narratives of the interviewed adolescents wove their life story, they are presenting significant data such as the relationship with the mother, the family context, the own act of adolescent and the dealing with conflicts in daily life as important aspects and as possible hypotheses to bring on the onset of obesity and overweight in these adolescent women. Each studied context, reveals singularities mother and daughter relationship and it stands as fundamental to the development and the construction girl s maturing in childhood, and mainly, in youth. / Nos dias de hoje, a obesidade se caracteriza como uma doença de causas múltiplas, sendo uma enfermidade grave e com alta incidência em países desenvolvidos e em desenvolvimento. Dessa maneira, é possível considerar que a obesidade pode ser analisada por vários aspectos multifatoriais como os genéticos, sociais e afetivos. Nesse sentido, esta dissertação aborda alguns aspectos afetivos presentes na problemática da obesidade e sobrepeso em adolescentes mulheres, procurando verificar possíveis falhas na relação afetiva mãe e filha, nos estágios precoces do desenvolvimento da menina. Este estudo está fundamentado em concepções teóricas de Winnicott (1983; 2000; 2005; 2006), Levisky (1995), Barbosa Silva (2005), Bruno (2011) e Cardoso (2008). Foi utilizada como procedimento metodológico a abordagem qualitativa da História Oral de Vida que privilegia as narrativas do sujeito como compreensão de suas vivências afetivas. Desse modo, foram feitas entrevistas gravadas com as adolescentes obesas ou com sobrepeso de 13 a 18 anos que fazem parte da triagem ou estão em tratamento nutricional na Clínica-Escola de Nutrição da Faculdade de Ciências Biológicas e da Saúde do Centro Universitário (Cesmac) em Maceió, Alagoas. Diante disso, as narrativas das adolescentes entrevistadas teceram sua história de vida, apresentando dados significativos como a relação com a mãe, o contexto familiar, o próprio ato de adolescer e o lidar com os conflitos existentes no dia a dia como aspectos importantes e como hipóteses possíveis de ocasionar o aparecimento da obesidade e do sobrepeso nessas adolescentes mulheres. Cada contexto estudado, revela singularidades da relação mãe e filha e se destaca como fundamental para o desenvolvimento e a construção do amadurecimento da menina na infância e, principalmente, na adolescência.

Dietary intake is a strong determinate of the health of an individual. Healthy eating is an important prevention to non-communicable diseases. If behaviour is to be changed insight into what the attitudes and barriers are to eating healthily amongst adolescents is imperative. This can provide knowledge for future prevention campaigns for healthy eating to prevent overweight and obesity. The purpose of the study was to quantitatively describe what attitudes adolescent females have towards healthy eating and what potential barriers omits them from adopting healthy eating behaviours. Data collection was done using structured questionnaires. Girls (N=73) from 3 public all girls’ high schools within Durban, KZN, participated in this study. The findings revealed that overall adolescent girls have a positive attitude to healthy eating. A lack of time, the foods sold in the school shop and the conveniences of less healthy food have been identified as barriers to healthy eating. / Health Studies / M. A. (Public Health)