With the rise of ‘globesity’, fat activism and Fat Studies have become political players in countering negative stereotypes and the devaluation of fat bodies. Both groups are diverse, yet share a common goal to celebrate and/or accept fatness, and challenge practices and discourses that reinforce ‘normal’ bodies (such as diets, ‘fat talk’ and medicalisation). In this article, we reflect on our engagement with a Fat Studies conference, and critically interrogate the assumptions that underlie this particular space. It is not surprising that fat activists and Fat Studies scholars bring different ideologies to the table, yet the differences between them have not been adequately scrutinised or theorised. Drawing upon Linda Alcoff’s feminist philosophy, we examine how identity politics and intersectional perspectives are both used in fat activism, yet have the effect of creating unresolved tensions between singular and multiple embodied identities. We argue that an identity politics approach (exemplified through embodied visibility and declarations of ‘thin privilege’) has the potential to create boundaries for policing and exclusion, and is thus at odds with the much broader axes identified by intersectorial approaches. Rather than dismiss the power of identity politics, we argue for a careful reframing of the relationship between identity politics and intersectionality in fat activism and Fat Studies. We suggest that unexamined contradictions that arise from this mismatch may be counterproductive to the important subversive aims of the movement.