Content area
Full text
1. Introduction
The obesity epidemic poses a substantial global public health threat. Harnessing influence from social networks is considered to be potentially promising to mitigate the obesity epidemic (Bahr et al., 2009). Prior research has shown that social networks have a critical impact on people’s health and health behavior, such as cessation of smoking (Christakis and Fowler, 2008), drinking (Osgood et al., 2013) and substance use in adolescence (Glaser et al., 2010). Network phenomena also appear to be relevant to weight-related behavior and outcomes (Christakis and Fowler, 2007). An individual’s perception of the social norms regarding weight-related behavior and the acceptability of obesity can be constrained or enabled by his or her social contacts, which further influences weight-control decisions such as food choices and dieting plans.
The arrival of online communities has allowed people to meet others with fitness needs more easily than ever before. Online weight-loss communities are intentionally designed to assist people in enhancing their weight management. Members can create profiles, join interest groups, seek and answer questions and track their weight on these platforms. To strengthen social cohesion, many online weight-loss communities provide the “buddying” (or friending) function to meet users’ demand for online buddies with similar needs. The buddy networks that are formed based on this function provide opportunities for individuals to build a long-term relationship with others and to lose weight together. The virtual space creates an anonymous online environment that enables members to feel free to express their “hidden selves” (Suler, 2002). It is convenient for members to connect with similar individuals without geographical restrictions. After becoming buddies, the user has full access to the other individual’s profile, and they can continuously exchange support. The news feed in the homepage enables users to sense the presence of their buddies and keep track of their online activities, such as reporting weight and adding new buddies. The user’s perception may then be constrained by his or her position in the buddy network and the behaviors of his or her network contacts. It is possible that users who observe their online contacts engaging in specific behaviors are more likely to engage in similar behaviors. Contagion may then occur when an actor’s behavior is transferred from his or her neighbor...