MSc (Med), Bioethics and Health Law, Faculty of Health Sciences, University of the Witwatersrand / Rising levels of obesity pose a major threat to the public health system in South Africa and in many other parts of the world. Yet the question of whether or not the prevention of obesity should become a matter for public health remains contentious. In this research report, I explore the issues that surround a high burden of obesity in South Africa, including some contributing factors and arguments for and against public health intervention. I will show how globalization, a consumerist culture and the media's representation of "the good life" have contributed to the obesity epidemic. In this context, I will argue that the South African government has a responsibility to curb increases in obesity levels.

Promoting physical exercise is necessary to combat childhood obesity. Walking to school is an encouraged physical activity, but the feasibility of walking to school depends on the walkability of the environment. During the last 40 years, the number of U.S. schoolchildren who walk to school has declined. The purpose of this evidence-based practice project was to perform a walkability assessment of the 2 largest communities in Wilson County Kansas to identify and address walkability issues. Frameworks for this practice initiative were social cognitive theory and the Health Promotion model. Questions for the project addressed whether sidewalks along the main pedestrian routes leading to the schools were in good enough condition to allow children to walk safely to and from school. Using an adapted tool from the Pedestrian Safety and Mobility Audit Guide, assessment of the condition of the sidewalks was completed using the key characteristics of the sidewalks such as width, evenness, surface, and condition in the 2 major school routes. Results indicated no safe walk route in Fredonia. In Neodesha, only the sidewalks on the west side of 8th Street were in excellent condition. Safety issues identified during the assessment led to recommendation of safe pedestrian travel on only one route to school. Findings may be used to promote daily physical exercise for children, which may reduce the risk for obesity and promote social change for the community.

acase@tulane.edu / Recent research has suggested a strong link between attention-deficit/hyperactivity disorder (ADHD) and obesity in youth. Both ADHD and obesity have high prevalence and are associated with an enormous personal, family, and social burden. Approximately 5% of children worldwide are currently diagnosed with ADHD, and the prevalence of obesity is estimated to increase relatively by 40% in children with ADHD. Thus, it is imperative to examine potential behavioral mechanisms that underlie comorbid ADHD and obesity, one of which may be abnormal eating behaviors. These behaviors compounded by ADHD symptomology contribute to weight gain in this population. Despite evidence that frequently sharing family meals may protect against abnormal eating behaviors, health-adverse behaviors, and overweight/obesity in youth, only half of families in the United States eat dinner together 6-7 nights per week. This study examines whether United States youth ages 10-17 who present with ADHD are more likely to be overweight/obese than those without ADHD and whether the frequency of shared family meals moderates this comorbidity. Data were obtained from the 2011/2012 National Survey of Children’s Health (NSCH). Using an ordinal regression analysis with moderation, the current study found that youth with ADHD are more likely to be overweight/obese. Frequency of shared family meals was not found to moderate the relationship between ADHD and weight status in the current study sample. Implications of the findings and suggestions for future research are discussed. / 1 / Emma Clare Lewis

Fibroblast Growth Factor 21 (FGF21) is an endocrine hormone derived from the liver that exerts pleiotropic effects on the body to maintain overall metabolic homeostasis. During the past decade, there has been an enormous effort to understand the physiological roles of FGF21 in regulating metabolism and to identify the mechanism for its potent pharmacological effects to reverse diabetes and obesity. Through both human and rodent studies, it is now evident that FGF21 is dynamically regulated by nutrient sensing and consequently functions as a critical regulator of nutrient homeostasis. In addition, recent studies with new genetic and molecular tools have provided critical insight into the actions of this exciting endocrine factor. Dissection of these FGF21-regulated pathways has tremendous potential for new targeted therapies to treat metabolic disease. The goals of this thesis are 1) to identify FGF21’s physiological role as a carbohydrate-regulated signal of macronutrient-specific satiety and 2) to determine the mechanism and tissues responsible for mediating the pharmacological effects of FGF21. To address the first goal, we used different FGF21 genetic knockout mouse models to determine if loss of FGF21 would affect macronutrient preference. We found that loss of FGF21 led to an increase in simple sugar intake whereas this had no effect on other macronutrients such as lipid or protein. To further characterize the relationship between carbohydrates and FGF21, in vitro and in vivo techniques revealed that FGF21 transcription in the liver increased in response to carbohydrate intake and this was dependent on the presence of a transcription factor activated by carbohydrates, ChREBP. We next addressed whether or not increased FGF21 levels would affect preference for simple sugars. We found that in response to increased circulating levels of FGF21, either through genetic overexpression or pharmacological administration, FGF21 would lead to a significant decrease in caloric and non-caloric sweeteners. Finally, we were able to determine that FGF21 was signaling to the hypothalamus to mediate this suppression of simple sugar intake through region specific knockout of the co-receptor beta-klotho. To address the pharmacological actions of FGF21, we generated an adipose-specific KLB KO mouse using mice that express Cre-recombinase under the adiponectin promoter. These mice lack the co-receptor for FGF21 in adipose tissue and are a more reliable adipose knockout model than previous studies that have used aP2-Cre mice. We were able to determine that the acute glucose lowering effects of FGF21 are mediated through direct signaling to adipose tissue and that FGF21 enhances insulin sensitivity by increasing glucose uptake in brown adipose tissue. However, FGF21 mediates its chronic effects, including lowering body weight and triglycerides, by signaling to some other non-adipose tissue. Overall our work has shown that FGF21 can significantly regulate glucose metabolism through multiple mechanisms.

Research Doctorate - Doctor of Philosophy (PhD) / Introduction: Surveillance data and other studies have indicated that the prevalence of overweight and obesity in preschool children in Ho Chi Minh City (HCMC) is increasing, particularly in urban areas. No studies have examined the speed at which this public health problem is emerging in child populations in urban Vietnam. Knowledge of the risk factors for preschool-aged child obesity is limited since earlier studies have been cross-sectional in design and potential risk factors at different levels have not been fully investigated. Objectives: This study aimed to assess the prevalence and trends in overweight and obesity, and to identify the risk factors associated with longitudinal changes in adiposity over a one year period in preschool children in urban areas of HCMC. In addition, a sub-study aimed to validate a proxy-questionnaire for use in measuring physical activity of preschool children. Method: Based on the available data from a cross-sectional study conducted with preschool children in HCMC in 2002, a restricted sample of 492 children aged four to five years from urban areas of HCMC was used for examining the trends in overweight and obesity in this child population, over the period from 2002 to 2005. The original study using the multi-stage cluster sampling was performed in preschool children aged one to six years in both urban and sub-urban areas of HCMC. A total of 1780 children aged one to six years participated in this study. Anthropometry of the subjects was measured using standard methods. Socio-demographic information was collected using a self-administered questionnaire. The one year follow-up study, using multi-stage cluster sampling, was conducted from 2005 to 2006 with children aged four to five years in preschools in urban areas of HCMC. At baseline, 670 children participated in the study and of these, 526 children completed two follow-up measurements at 6 month intervals. Information on neighbourhood, preschool and home environments, socio-economic status, the child’s and parental characteristics were collected using pre-coded, structured, interviewer-administered questionnaires. Dietary intake and physical activity were measured in the home and preschool settings using modified, validated questionnaires. Anthropometry including weight, height, skinfold thickness at triceps, subscapular and suprailiac sites were measured using standard methods. The trends in overweight and obesity were examined based on data from the 2002 study and the baseline study of the cohort study. Data were collected in 2002 and made available for these secondary analyses. The validation study of the proxy-questionnaire to measure physical activity of children aged four to five years was conducted from July, 2005 to November, 2005, using accelerometers as the criterion method. A subset of 83 children from the entire cohort study participated in this study. Physical activity data over the three months, reported by the teacher and the parents, were compared with data collected from the accelerometers for seven consecutive days. Main outcomes: Body mass index (BMI) was calculated from measured weight and height. Overweight and obesity were defined using IOTF cut-off points. Underweight was classified using the 5th percentile cut-off point for weight for age, based on the 2000 CDC Growth Reference. Results: The findings indicated that the significance of overweight and obesity in preschool children in urban areas of HCMC is not only in its magnitude (obverweight: 20.5% and obesity: 16.3% in 2005), but also in the rapidly increasing trend in prevalence from 21.4% in 2002 to 36.8% in 2005. There exists an imbalance in food intake in this young child population. Dietary patterns have shifted towards higher energy obtained from protein and fat (particularly animal protein and fat) and less energy from carbohydrates, than is recommended. The risk factors of overweight and obesity in the four to six year old child population in HCMC were identified at multiple levels. The contextual variables in the community, school and home environments, interacted with individual characteristics influencing the changes in adiposity and overweight and obesity development over time. Risk factors for changes in adiposity and risk of developing overweight and obesity differed for boys and girls. The proxy-questionnaire was shown to be valid for ranking the child’s sedentary behaviour but it was not suitable for measuring the child’s physical activity patterns in absolute values. Conclusion: An obesity epidemic has been taking place in the young child population in urban areas of HCMC. Boys appear to be more vulnerable to this epidemic than girls. The diet of this child population has shifted to higher energy from protein and fat, and less energy from carbohydrate. The aetiology of overweight and obesity of preschool children ismulti-factorial. It is time for action to control this public health problem in young children in urban areas of HCMC, Vietnam.

Obesity is reported to be an epidemic (Cameron et al. 2003; Contaldo and Pasanisi 2003), particularly in western countries with 31 % of adults aged over 20 years in the US either overweight or obese in 1999-2000 (CDC 2004). A similar situation is reported in Australia with 16.7 % of the adult population (aged 18 or older) obese in 2001 and 34.4 % overweight (Australian Institute of Health and Welfare 2003). The US Surgeon General (1996) highlighted the link between increasing girth and decreasing activity levels and suggested that moderate intensity activity such as frequent walking could improve the health outcomes for overweight and obese people. Current public health recommendations emphasize the benefits of accumulating 30 minutes of moderate intensity physical activity, such as walking, daily (Sallis et al. 2004). As walking for health reasons is important, factors that influence people to walk, in particular environmental influences, are the subject of a considerable research effort. A wide range of factors have been associated with walking behaviour by the public health professionals and transport and town planners, due to the recognition that neighbourhood design and land use may affect transport choice, such as automobile, public transit or walking/cycling (Saelens, Sallis and Frank 2003). A range of characteristics that are correlated with higher rates of walking review have been identified from the literature and grouped as the 3Ds (Cervero and Kockelman 1997) or proximity and connectivity (Sallis et al. 2004; Saelens, Sallis & Frank. 2003; Frank and Engelke 2001). Consistently, population density, land use mix, the street network and retail access are linked with definitions of neighbourhoods as either supporting walking behaviour or automobile dominated. This aim of this project is to build an objective walkability index based upon the physical environmental factors identified from the research and apply this to Adelaide, a large urban city in Australia using geographic information systems (GIS). Specifically, this study will build upon the work from the US (Frank et al. 2005) in delimiting cities into walk friendly or unfriendly, adapted to Australian data to provide the basis for an index that can be applied to Australian cities to highlight the variations across cities and between cities. / Thesis (M.A.)--School of Social Sciences, 2005.

Thesis (Ed. D.)--Illinois State University, 2005. / Title from title page screen, viewed on April 16, 2007. Dissertation Committee: Thomas P. Crumpler (chair), R. Kay Moss, Gary Weilbacher, Amelia Adkins, Sally Parry. Includes bibliographical references (leaves 151-168) and abstract. Also available in print.

Thesis (M. Soc. Sc.)--University of Hong Kong, 2006.

Obesity is an accumulation of adipose tissue to the point of negative health outcomes; the association of obesity with type 2 diabetes and cardiovascular disease is particularly profound. Notably, obesity has begun to be associated with impairments in cognitive function; however, the underlying cellular mechanisms are poorly understood. Behavioural studies have demonstrated a link between a high fat diet and impaired hippocampal function, and our aim was to characterize protein level changes in the hippocampus of an obese female rat model. Female rats were fed either a control diet (CD; 10% kcal from fat), or a high-fat diet (HFD; 45% kcal from fat) for 16 weeks. Body weight, food consumption, fasting blood glucose levels, and glucose tolerance were monitored. Upon sacrifice brain, liver, adrenal glands, spleens and fat pads were harvested and analyzed. Plasma leptin and insulin levels were also measured. The distribution of NMDA receptor subunits was examined by using either cell-surface biotinylation, or differential filtration-centrifugation followed by immunoblotting. The feeding protocol induced an obese phenotype in female rats characterized by larger fat pads, spleens and adrenal glands, as well as greater problems handling a glucose load. However, cellular, surface and synaptic expression of NMDA receptor subunits (GluN1, GluN2A & GluN2B) were not significantly altered, which suggests that changes downstream of the receptor may be responsible for the effects of HFD on cognitive behaviour.

Fetal overgrowth is associated with adverse outcomes for offspring and with maternal obesity. Results from a systematic review and meta-analysis showed that maternal obesity is associated with fetal overgrowth, defined as birthweight ≥4000g (OR 2.17, 95% CI 1.92, 2.45), birthweight ≥4500g (OR 2.77, 95% CI 2.22, 3.45) and birthweight ≥90%ile for gestational age (OR 2.42, 95% CI 2.16, 2.72). A retrospective cohort study revealed that mothers whose infants are macrosomic are more likely to require induction of labour (OR 1.42, 95% CI 1.10-1.98) and delivery by Cesarean section (OR 1.45, 95% CI 1.04-2.01), particularly for maternal indications (OR 3.7, 95% CI 1.47-9.34), if they are obese. Infants from these pregnancies are significantly more likely to require neonatal resuscitation in the form of free flow oxygen (OR 1.57, 95% CI 1.03, 2.42) than macrosomic infants of non-obese mothers. Thus, co-existing maternal obesity and macrosomia increases the risk of adverse pregnancy outcomes.