Longitudinal relationships between anti-fat attitudes and muscle dysmorphia symptoms

Weight stigma, and more specifically, anti-fat attitudes, is associated with disordered eating. Furthermore, these anti-fat attitudes influence various appearance ideals. Muscle dysmorphia (MD) is characterized by preoccupation with the muscular ideal and is a potential form of disordered eating commonly experienced by men. Despite theory suggesting that anti-fat attitudes may contribute to MD, research has yet to examine associations between anti-fat attitudes and MD symptoms. Therefore, the current study investigated longitudinal relationships between anti-fat attitudes and MD symptoms. Participants were 269 U.S. men recruited from Prolific who completed three self-report surveys each separated by one month. Primary analyses examined longitudinal relationships between specific anti-fat attitudes and MD symptoms using an adapted three-wave cross-lagged panel model. Results demonstrated that believing that fat people do not have willpower was longitudinally associated with desires to increase muscle size at multiple time points. Furthermore, MD-specific functional impairment predicted fears of becoming fat longitudinally. Practically, men may desire to increase their muscularity to demonstrate their own willpower and distance themselves from anti-fat stereotypes. Thus, clinicians may consider targeting weight stigmatizing attitudes to reduce MD symptom severity among their male clients.