Do differences between individuals who are healthy weight or overweight on self-report measures of disinhibited eating and restrained eating reflect reality or item "bias"?

In light of increasing rates of overweight and obesity worldwide, there is a critical need for accurate self-report measures of disinhibited and restrained eating behaviors across the weight spectrum. Item response theory was used to determine whether differences in disinhibited and restrained eating between healthy weight and overweight or obese individuals were due to item bias (i.e., differential item functioning). Study 1 participants were healthy weight ( = 510) or overweight or obese ( = 304) adults recruited from the community. Study 2 participants were healthy weight ( = 778) or overweight or obese ( = 320) college students. Study 1 participants completed the Eating Disorder Examination-Questionnaire (EDE-Q), Eating Disorder Inventory-3, Dutch Eating Behaviors Questionnaire, Restraint Scale, and Three-Factor Eating Questionnaire. Study 2 participants completed the Eating Pathology Symptoms Inventory (EPSI). Items on the Restraint Scale demonstrated the most evidence for bias (60% of items), whereas the majority of other scales demonstrated low to moderate levels of item bias (17-38% of items). However, EDE-Q Restraint and EPSI Binge Eating, Cognitive Restraint, Excessive Exercise, Muscle Building, and Negative Attitudes Toward Obesity scales did not show any evidence of differential item functioning among weight groups. Participants with the same level of disordered eating responded differently to certain eating disorder self-report items due to weight-bias, rather than true between-groups differences. Nevertheless, EDE-Q Restraint, EPSI Cognitive Restraint, and EPSI Binge Eating did not exhibit any evidence of bias and are ideal for assessing restrained and disinhibited eating across the weight spectrum in both research and clinical settings. (PsycInfo Database Record (c) 2020 APA, all rights reserved).