The impact of social influence upon adolescents' exercise and eating behaviours

Many adolescents in the UK do not meet the recommended government guidelines for physical activity and diet. The impact of social influence upon adolescents' exercise and healthy eating behaviours is poorly understood. In this thesis, social influence is defined as occurring when an individual's thoughts and/or actions are affected by sources, such as parents, friends, and people in the media. However, the processes through which these sources influence individuals are poorly understood. The aim of the research was to explore the impact of social influence upon adolescents' exercise and healthy eating behaviours using a mixed methods approach, specifically exploring any age and gender similarities and/or differences. To achieve this aim, three studies were conducted using differing types of methodology. Study 1 used a Theory of Planned Behaviour based questionnaire, with additional normative measures, to explore adolescents' (overview analyses n = 712, subsequent analyses n = 335) exercise and healthy eating intentions and behaviours. Analysis of the data revealed that there were differences within the age and gender groups, regarding the sources and processes of influence for adolescents' exercise and healthy eating intentions and behaviours. Study 2, a semi-structured interview study, built upon these findings and explored social influences in greater depth (n = 24). Parents were the most influential sources for younger adolescents, and friends for older adolescents. These influences operated through a variety of processes, which were captured by the over-arching themes of encouragement and modelling. Study 3 used Q methodology to further explore adolescents' (n = 60) views of the sources and processes of social influence for exercise and healthy eating. Similarities and differences in views between age and gender groups were again explored. For exercise, there were four understandings of adolescents' views: 'if mum and dad say and do it, I do it too', 'I enjoy it, so I do if, 'you want me to do it, I'll do it', and 'my mother, my role model'. There were also three understandings of adolescents' views for healthy eating: 'parent power - what mum and dad say, goes', 'I do it my way', and 'mother knows best'. The research within this thesis demonstrates that it is important to not only promote healthy ways of thinking and behaving to adolescents as individuals, but to significant others around them. Suitability of the methods used are also evaluated and recommendations made for further research.