Key terminologies.

Behavioral health and economics rely on understanding underlying mechanisms of action. Drawing from a randomized controlled trial (RCT) conducted among low-income Jordanians and Palestinian refugee communities, this study investigates how individual motivations affect collective actions in a behavioral weight loss program within social networks. Participants were randomly assigned to one of three trial arms: Full Microclinic Social Network Intervention (MCP) with curriculum-activated and organic social network interactions; Basic MCP educational sessions with organic social network interactions; or Controls receiving standard care along with active and parallel monitoring. Analysis of the RCT data strongly indicates that behavioral change is repeatedly driven by a “Leader Domino Effect” rather than an average peer pressure. The estimated net leader domino effect for Full and Basic MCP, relative to the control group, is weight loss of 0.207 kg per two weeks (95% CI: 0.103 to 0.311) and 0.123 kg per two weeks (95% CI: 0.006 to 0.241), respectively, on subsequent weight loss. No effects were found for average classroom weight loss on subsequent weight loss. Findings indicate leadership influences exceed average group effects in understanding collective behavioral health and its implications for addressing societal challenges.