Unhealthy diet, low levels of physical activity, high levels of sedentary behaviour and sleep deprivation are important weight related behaviours that have contributed to the increased prevalence of adolescent obesity. Numerous interventions have been developed to improve weight-related behaviours but they are usually focused on the individual and they ignore the effects of social networks on these behaviours. Much of the research in obesity has explored the role of social networks in promoting health through social influence and selection. However, little research has examined how the structure of social networks and the position of the individuals in the network could condition behaviour association (regardless of the underlying mechanism being social influence or selection) in adolescent friendship networks. Examining social network structure, individual position in the network and how they interact with individual behaviour in friendship networks can assist in better understanding the development and persistence of weight-related behaviours in adolescent friendship networks and provides valuable insight on how to modify these behaviours. Hence, this study aims to examine the role of friendship network properties (density, popularity and centrality) on the association between individual's and friends' weight-related behaviours after reviewing the literature and analysing social network and behavioural survey data. Methods are drawn from a set of analytical tools known as 'Social Network Analysis', which uses friendship nomination data from a complete network (socio-metric), along with reported data on diet, physical activity, sedentary behaviour, and sleep deprivation to investigate how friendship network structure is moderating behaviour association between individuals and their friends in the network. Four schools in Kingdom of Bahrain participated in the study with a total of 673 adolescents between the ages of 11 and 15. Findings suggest that there are associations between adolescents and their friends' in multiple weight-related behaviours. There is also evidence for the moderating role of some network properties on these associations. Findings are gender specific, which has implications for gender-tailored interventions.