Cooper, JoelShields, Justin2025-08-052025-08-052025-04-21https://theses-dissertations.princeton.edu/handle/88435/dsp01pk02cf18tWeight stigma remains a pervasive form of bias, even as explicit prejudice related to race and gender has declined. Ironically, healthcare providers are among the most frequent sources of weight-based discrimination, with consequences for patient trust, healthcare utilization, and treatment outcomes. To address this issue early in professional development, the present study tested a brief, theory-driven intervention targeting implicit and explicit anti-fat bias in premedical undergraduates. Grounded in cognitive dissonance theory and integrating elements of attribution theory, social identity, and the Elaboration Likelihood Model (ELM), the intervention included educational materials, a counterattitudinal essay, and a public pledge. Participants (n = 51) were randomly assigned to either an intervention or control condition and completed baseline and posttest measures of implicit bias (IAT), explicit attitudes (AFAT, BAOP), and internalized weight stigma (WBIS-M). Results revealed significant reductions in both implicit and explicit anti-fat bias in the intervention group compared to the control group, with medium-large effect sizes. These findings demonstrate that dissonance-based strategies, when supplemented with identity- and empathy-relevant content, can reduce bias even at the level of automatic associations. Keywords: cognitive dissonance, explicit attitudes, implicit bias, obesity, weight stigmaen-USPrinceton University Senior Theses