This article analyses anti-obesity discourse in post-war Czechoslovakia, particularly in the country’s late socialist period. The article conceives of the discourse on obesity as a tool of biopolitical, rather than totalitarian, power, examining the ways expert knowledge, power, and morality worked together to produce a socialist subject. On the first level, it analyses the expert anti-obesity discourse as an example of the expertisation of public discourse in socialist Czechoslovakia. Second, it shows the construction of obesity in contrast to bodily ability, and the stigmatisation of the ‘fat’ body. On the last level, the article focuses on the gendered aspects of the discourse and demonstrates the ways in which the anti-obesity campaign supported the heteronormative framework of late socialism. By examining expert and media discourses, the article argues that the campaign against obesity served as a means to construct a proper socialist body and induce a moral panic about the state of socialism.