At present, most work examining the well-documented relationship between social inequality and body size treats fatness as an effect, caused either by some factor that determines weight and social class simultaneously, or by social class itself. However, the relationship between weight and social inequality is more complex than these explanations suggest. Recent studies by John Cawley (2004) and Charles Baum and William Ford (2004) suggest that fatness is often a contributor to inequality, not merely an effect. This article examines the causes of income inequalities between obese and nonobese workers, focusing on how gender interacts with body size to determine the size and duration of those inequalities. Drawing on data from the 1997–2008 National Longitudinal Survey of Youth (NLSY97), I introduce a positive test for discrimination, which provides a methodological advantage over previous research in this area. I then pose two questions: first, is anti-obesity discrimination to blame for income inequalities between obese and nonobese workers? Second, do women and men's experiences of those inequalities differ? The results indicate that very obese men do face one form of discrimination–statistical discrimination–but that they can overcome initial disadvantages with time. In contrast, obese women's income disadvantages persist over time, suggesting the presence of prejudicial discrimination. In combination with previous studies illustrating how fat women are disadvantaged in educational attainment and marriage outcomes–two important means of accessing economic resources–this research shows one mechanism by which weight, particularly in combination with gender, is a major vector of U.S. inequality.