Recent studies suggest that eating disorders are increasing in Mexico and that this seems to correspond with Mexico's push to modernization. In this respect, Mexico exemplifies the acculturation hypothesis of eating disorders, namely, that anorexia and bulimia are culture-bound syndromes tied to postindustrial capitalist development and neoliberalist values, and that their appearance elsewhere is indicative of acculturation to those values. Available evidence for this claim, however, is often problematic. On the basis of five years of comparative fieldwork in eating disorder clinics in Mexico City and a small Midwestern city in the United States, I reframe this as an ethnographic question by examining how specific clinical practices at each site entangle global diagnostic categories with local social realities in ways that problematize existing epistemologies about culture and illness. In this regard, debates about acculturation and the global rise of eating disorders foreground issues of central epistemological and practical importance to contemporary medical anthropology more generally.