Across industrial societies, there is an inverse relation between body size and social class: the higher one’s class position and the lower one’s body size, particularly for women. The most stigmatized body type, on both aesthetic and moral grounds, is therefore linked with structural, intergenerationally transmitted advantage and disadvantage. In this chapter, we review existing explanations of the relation between body size and social class, from epidemiology and the health sciences, social psychology, sociology and fat studies. We then present a new sociological perspective on weight differences, based on the ‘embodied’ sociology of Pierre Bourdieu that moves beyond concerns with large body size as epidemic or individual pathology (or happens in health sciences), or as social stigma (as it is commonly seen in psychology and fat studies). We argue that it might be most productive to think of body size not as simply another intersecting axis of inequality, alongside gender, sexuality or, indeed, social class, but instead, that think of body size as a more direct expression of class habitus, which cannot be analytically separated from this ‘axis’.