Bias against overweight people is documented; however, little attention has been directed to bias against thin people. Theoretically, light and heavy bodies can invoke an affective mechanism leading to bias and avoidance of those different physically from the average. Participants (N = 62) rated six same or opposite sex targets varying randomly in weight. Ratings of traits and liking were curvilinear as a function of weight and showed bias against light and heavy targets. For heavy targets, negative affect predicted discriminatory behavioural intentions; stereotypes did not. Copyright © 2011 John Wiley & Sons, Ltd and Eating Disorders Association.