Metacognitive confidence independently predicts body image delusionality in anorexia and bulimia nervosa

Body image beliefs in eating disorders (EDs) are often characterized by high conviction and resistance to corrective evidence. Although perceptual distortion has been widely implicated, body image delusionality may also depend on higher-order belief evaluation processes. We examined whether confidence in body-size judgments is associated with body image delusionality beyond perceptual misestimation.

Ninety-seven adult female patients with EDs, 51 with anorexia nervosa (AN) and 46 with bulimia nervosa (BN), were assessed using the Brown Assessment of Beliefs Scale (BABS). Body-size perception was evaluated with the Contour Drawing Rating Scale, including current and ideal size estimates, body dissatisfaction (the absolute current-ideal discrepancy), misestimation (the signed discrepancy from clinician ratings), and confidence in body-size judgments. Associations were examined using non-parametric analyses with false discovery rate correction for the body-size perception correlations, and hierarchical regression models.

Delusional body image beliefs were more frequent in AN than BN (29.4% vs 2.2%). At the bivariate level, delusionality was associated with current size ratings, body dissatisfaction, misestimation, and confidence. In hierarchical regression analyses, perceptual indices explained little variance in delusionality. After entering confidence in the final step, confidence emerged as the sole independent predictor and substantially increased explained variance (final model R² = 0.34).

Body image delusionality in EDs appears more strongly related to metacognitive confidence than to perceptual distortion. These findings support a dimensional account of delusionality and suggest that confidence in body-size judgments may contribute to persistent distorted body image beliefs, although the cross-sectional design precludes causal inference.