Weight Bias Internalization Is Inversely Associated with Adherence to the Mediterranean Diet: The Greek Lifestyle and Obesity-Related Bias Survey

Background/Objectives: Internalized weight bias has been linked to adverse mental health outcomes and maladaptive eating-related behaviors. However, its relationship with habitual dietary intake and overall diet quality remains insufficiently explored. The objective of this study was to examine associations between internalized weight bias and habitual energy intake, macronutrient composition, and adherence to the Mediterranean diet among adults with a history of overweight or obesity. Methods: In this web-based cross-sectional study, 484 adults with a history of excess body mass index completed validated assessments of internalized weight bias (Weight Bias Internalization Scale–Modified; WBIS-M) and usual dietary intake (69-item Food Frequency Questionnaire). Adherence to the Mediterranean diet (MeDi) was assessed via the MedDietScore. Multivariable analyses adjusted for several covariates were performed. Results: Higher levels of internalized weight bias were associated with lower adherence to the MeDi (Badj = −0.670, p = 0.025). Higher adherence to the MeDi was associated with reduced odds of being classified in the medium or the highest WBIS-M tertile, corresponding to an approximately 5% reduction per 1-unit increment in the MedDietScore. No associations were observed between internalized weight bias and total energy intake. At the macronutrient level, higher internalized weight bias was associated with higher saturated fat intake, independent of total energy intake. Conclusions: Internalized weight bias was associated with poorer habitual diet quality and unfavorable macronutrient profiles, independent of total energy intake. These findings suggest that internalized weight bias relates to qualitative differences in habitual food choices, highlighting the potential importance of addressing weight bias in efforts to improve diet quality among adults with overweight or obesity.