Child and adolescent obesity: prevalence and risk factors in a rural South Africa population

The World Health Organization estimates that 22 million children worldwide aged <5 years are overweight and highlights tackling childhood obesity as an urgent priority. Childhood obesity is rising to epidemic proportions in the developing world, reflecting changing physical activity levels and dietary intakes, adding a significant public health burden to countries where undernutrition remains common. Interventions to prevent childhood obesity have had disappointing results, because the science and aetiology of obesity is poorly understood and prevention programmes have not targeted appropriate behaviours nor adequately engaged communities being studied. The origins of obesity appear simple, excess energy intake and/or low energy levels expended on physical activity, leading to chronic energy imbalance. However, the problem is more complex with underlying societal, behavioural and genetic causes of energy imbalance remaining unclear. Obesity is driven by individual, household and community factors: research to date has concentrated on individual factors with almost no significant focus on higher level influences on obesity. Findings from studies in developed countries are unlikely to be applicable to rural African settings where there is an increasing transition from a state of undernutrition to that of overnutrition. Few data exist on the prevalence of child and adolescent obesity from low and middle income countries like South Africa. This thesis aimed to determine the prevalence of overweight and obesity in children and adolescents (aged 7-15 years) within this population and to identify possible risk factors. Participants and Methods The study was cross-sectional and involved collecting primary data in local schools. A total of 1,519 subjects were recruited from three age groups (approximately 500 from each age group 7, 11 and 15 years). Participants were recruited from school grades 1, 5 and 9 corresponding to the ages 7, 11 and 15 years respectively. The study comprised two parts, a main cross-sectional study and a further study including a sub-sample of the participants. In the main cross-sectional study anthropometric measurements (height, weight, mid-upper arm circumference and body fat) were performed on all the participants and a lifestyle questionnaire administered (questions related to water collection, travel to school, TV watching and sport participation). The study took place in a demographic surveillance area and data collected from participants was linked with their household/community data to allow analysis of variables associated with overweight/overfat status. 150 participants were randomly selected from the main study (50 from each age group 7, 11 and 15 years) and invited to take part in a sub-sample study which included objective measurement of physical activity (7 days accelerometry) and dietary assessment (2 x 24 hour multiple pass recall assessments) on each participant. Main Findings Prevalence of overweight and obesity was higher in girls than boys and was highest in the oldest age groups for females. Using the Cole/IOTF BMI for age reference combined overweight and obesity was 23% in grade 9 females compared to only 6% in boys in the same grade (p