Once again, the link between social influence and obesity is identified. Markets could conceivably use this more powerfully in “bring a friend” campaigns or by keeping healthy recipes at trusted vendor tables rather than at generic tables or maybe with “2 for 1” specials for SNAP incentives….

The spread of obesity in social networks appears to be a factor in the obesity epidemic. Yet the relevance of social influence also suggests that it may be possible to harness this same force to slow the spread of obesity. Network phenomena might be exploited to spread positive health behaviors,34-36 in part because people’s perceptions of their own risk of illness may depend on the people around them.37 Smoking- and alcohol-cessation programs and weight-loss interventions that provide peer support — that is, that modify the person’s social network — are more successful than those that do not.34,35,38,39 People are connected, and so their health is connected.40,41 Consequently, medical and public health interventions might be more cost-effective than initially supposed, since health improvements in one person might spread to others.42 The observation that people are embedded in social networks suggests that both bad and good behaviors might spread over a range of social ties. This highlights the necessity of approaching obesity not only as a clinical problem but also as a public health problem.

The Spread of Obesity in a Large Social Network over 32 Years — NEJM.