The role of sisters in body image dissatisfaction and disordered eating

The Tripartite Influence Model (TIM) argues sociocultural agents affect body image dissatisfaction (BID) via the mediators of social comparison and internalization. BID subsequently influences disordered eating. Forty-seven Australian sister pairs (18–25 years) provided self-reports of perceived familial modeling and pressure by the sociocultural agents of mother, father and sister, social comparison, internalization, BID, bulimic behaviors, and dietary restriction. Sisters were correlated on internalization, BID, disordered eating, and parental modeling and pressure. Mothers and sisters were equally important modeling agents. Sisters were an equivalent social comparison target to peers. Consistent with the TIM, internalization and social comparison mediated familial pressure on BID. Contrary to the model, sister modeling directly affected bulimic behaviors and dietary restriction.