Implicit attitudes toward dieting and thinness distinguish fat-phobic and non-fat-phobic anorexia nervosa from avoidant/restrictive food intake disorder in adolescents

Objective: The majority of individuals with anorexia nervosa (AN) have a fat-phobic (FP-AN) presentation in which they explicitly endorse fear of weight gain, but a minority present as non-fat-phobic (NFP-AN). Diagnostic criteria for avoidant/restrictive food intake disorder (ARFID) specifically exclude fear of weight gain. Differential diagnosis between NFP-AN and ARFID can be challenging and explicit endorsements do not necessarily match internal beliefs.

Method: Ninety-four adolescent females (39 FP-AN, 13 NFP-AN, 10 low-weight ARFID, 32 healthy controls [HC]) completed implicit association tests (IATs) categorizing statements as pro-dieting or non-dieting and true or false (questionnaire-based IAT), and images of female models as underweight or normal-weight and words as positive or negative (picture-based IAT). We used the Eating Disorder Examination to categorize FP- versus NFP-AN presentations.

Results: Individuals with FP-AN and NFP-AN demonstrated a stronger association between pro-dieting and true statements, whereas those with ARFID and HCs demonstrated a stronger association between pro-dieting and false statements. Furthermore, while all groups demonstrated a negative implicit association with underweight models, HC participants had a significantly stronger negative association than individuals with FP-AN and NFP-AN.

Discussion: Individuals with NFP-AN exhibited a mixed pattern in which some of their implicit associations were consistent with their explicit endorsements, whereas others were not, possibly reflecting a minimizing response style on explicit measures. In contrast, individuals with ARFID demonstrated implicit associations consistent with explicit endorsements. Replication studies are needed to confirm whether the questionnaire-based IAT is a promising method of differentiating between restrictive eating disorders that share similar clinical characteristics.