modeling the influence of social networks and environment on energy balance and obesity
DESCRIPTION
Modeling the influence of social networks and environment on energy balance and obesity. P Giabbanelli, A Alimadad, V Dabbaghian, DT Finegood. ICO, Stockholm July 14, 2010. Social Network Analysis. Obesity can spread through social networks. Christakis and Fowler. NEJM 357: 370, 2007. - PowerPoint PPT PresentationTRANSCRIPT
Modeling the influence of social networks and environment on energy balance and obesity
P Giabbanelli, A Alimadad, V Dabbaghian, DT Finegood
ICO, Stockholm July 14, 2010
Social Network Analysis
• Obesity can spread through social networks
Christakis and Fowler. NEJM 357: 370, 2007
Social Network Simulations
• Traditional interventions fail because they target individuals without consideration of their social network.
• Dieting with friends is ineffective compared to dieting with friends of friends.
Bahr et al. Obesity (2009) 17, 723–728.
What spreads? Outcome or behaviour
• Previous studies have only considered the spread of obesity.
• Body weight is the product of food and physical activity related behaviours.
• Social network effects are only one type of environmental influence on food and physical activity behaviour.
• Marketing, the built environment, agricultural policy and many other factors also influence behaviour.
Objective
• To investigate the impact of social network and environmental influences on physical activity and energy intake.
Core Model
Social Network and Environmental Influences on Physical Activity
Sample Network
Network’s Influence
where• C is either physical activity (PA) or energy intake (EI)• F is an individual’s set of friends
))1()1((||
1)(
tCtCF
Inf iFij
ji
C ti
Social Network and Environmental Influences on Physical Activity
Change in Physical Activity
where:• I is the impact on physical activity (PA) • T is the threshold that needs to be achieved to
trigger change
Simulations• To identify the relative contributions of specific
factors we used a factorial design that tested all combinations of low and high values for:– Environmental influence (Env)– Thresholds for changing PA and EI (TPA, TEI)
– The impact on changing PA and EI if the threshold is exceeded (IPA, IEI)
– and network topology (small world, scale free)
Results
Conclusion
• Individuals are influenced by both their environment and their social network with a similar order of magnitude.
• While social network influences are important to changes in weight status, they should not be considered independent of other biological and environmental factors.
Acknowledgement
• This works was supported by the Canadian Institutes of Health Research (MT-10574) and the Modeling of Complex Social Systems Program (MoCSSy) at Simon Fraser University.