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In adulthood, being overweight or obese increases the risk of many cancers. Overweight and obesity are at high levels among youth and are liable to precede overweight and obesity in adult life. Preventing childhood obesity is therefore essential for the long term prevention of adult cancer.
Identification of the modifiable factors in youth that may lead to the development of obesity is therefore essential to finding ways to prevent obesity and cancer risk. One such factor is physical inactivity, which has been associated with obesity in both adults and children. Fruit and vegetable consumption is associated with lower levels of obesity among adults and children, and epidemiological studies show an inverse relationship between dietary intake of fruit and vegetables and incidence of cardiovascular disease, stroke and cancer in adulthood.
Despite these benefits, many children and adolescents have levels of physical activity and fruit and vegetables consumption below recommended guidelines. In this application we will also explore a potential mechanism by which environmental stress may influence the development of obesity with a focus on whether the stress hormone cortisol functions as a mediator in the relationship between behaviours and obesity.
Over 1300 young people have already been recruited to the first phase of this study whilst in primary school. 953 of these have also been followed up in their first year of secondary school. This study will measure the children again now that they are 14 years old.
This will allow us to investigate whether changes in physical activity and eating behaviours that we discovered between primary and secondary school are continued into later adolescence. They will have their activity measured with activity monitors, will wear GPS receivers to record journeys to and from school and in the evening, and will complete computerised questionnaires to measure personal, social and environmental factors believed to be associated with eating behaviours, physical activity and obesity. On one day they will provide a saliva sample 5 times during the day for measurement of cortisol.
Few if any existing data sets have measured the wide range of personal and environmental variables available in PEACH, and this study thus provides a unique opportunity to investigate how longitudinal changes in health behaviours and obesity are associated with environmental variables.
The integration of neuroendocrine processes e.g. increased cortisol secretion, into traditional models of obesity holds promise for illuminating mechanisms by which physiological processes may influence the development of obesity and indicates new directions in understanding and preventing childhood obesity.
Overweight and obesity in the young are increasing rapidly, and the environment is believed to play a role in this. However there are few data that describe how the environment may influence eating behaviours or physical activity. The main hypothesis for this study is that the environment (physical, home or school) in which a young person lives is associated with consumption of healthy or unhealthy foods and/or their level of physical activity, and that these factors are associated with obesity. Our objective is to measure a wide range of environmental correlates of eating and physical activity behaviours, and to generate a theoretical model of how the key behaviours interact to help to explain their association with obesity. One thousand students will be recruited in their first year of secondary school and followed up two years later. They will have their activity measured with activity monitors, will wear GPS receivers to record journeys to and from school and at lunchtime, and will complete computerised questionnaires to measure personal, social and environmental factors believed to be associated with eating behaviours, physical activity and obesity.