In this chapter I argue that even if – as popular prejudice suggests – it were possible to make inferences about character traits or personal abilities from the amount of body fat a person carries, this would do nothing to justify discrimination. In the first section, I briefly indicate the evidence for widespread discrimination against obese people in modern developed societies, and note some debates about appropriate language. In the second section, I highlight some distinctive features of obesity as a ground of discrimination. Most importantly, weight bias is still widely acceptable, and its justifications find institutional support insofar as medicine stresses that obesity is bad and, perhaps, remediable. This brings us to some facts about health and obesity, which are too often simplified in public discussions. I then turn to the wrong of obesity-based discrimination. I argue that the standard rationalisations are untenable, and not only because their factual premises are so dubious. Philosophically, they rest on illiberal confusions about the appropriate place for personal judgments. In our private lives, we may well respond to others on the basis of their body shape or our personal estimates of their virtues or abilities. (Just as they may respond to us in their turn!) When we engage in different forms of civil association, however, anti-discrimination provisions remind us what is, and what is not, ‘our business.’ They thereby help to uphold norms of equality, freedom and respect.