<p><strong>Stigma and discrimination based on body size is pervasive in Western society. Weight-based stigma among mental health professionals is common, with harmful and unfounded assumptions about weight affecting diagnosis and treatment. Fat bias further intersects with other forms of oppression such as sexism, racism, classism, and ableism. Psychologists have an ethical and professional responsibility to work towards recognising and resisting oppressive discourses and practices in health care. In this study, I sought to understand the ways in which clinical psychologists in Aotearoa New Zealand both uphold and resist harmful dominant discourses about fatness in their clinical work with fat clients.</strong></p><p>This research was critical, exploratory, and qualitative in design, drawing on principles of social justice and critical discursive psychology. Semi-structured interviews were conducted with 20 clinical psychologists located across Aotearoa New Zealand working in mental health or medical settings. Thematic discourse analysis was used to analyse the transcribed interview data. The results indicate that the participants largely reproduced biomedical and neoliberal discourses, as well as Eurocentric psychological tenets that psychopathologised the causes of fatness; favoured a dualistic approach to the mind-body relationship; neglected the body as a site of meaning and identity; and disregarded the social, structural, and cultural determinants of health. Participants’ views of fat client subjectivities intersected with clients’ other marginalised identities, including gender, race, and ethnicity. Most participants reported discomfort with the topic of their client’s fat body, and frequently evidenced avoidance of the topic. Participants positioned themselves as either ‘health advocates’ whose obligation was to support the client’s pursuit of ‘health’, or as ‘client advocates’, who sought to protect the client from shame associated with their fat body. Participants were seen to attempt to resolve the tensions between these opposing positions by ignoring the fat body, enacting a kind of ‘fat erasure’ in therapy. Participants further reported difficulty with finding appropriate language for talking about fatness, with all terminology surrounding fatness considered to be ‘troubling’. Recommendations include addressing psychologists’ bias towards fatness in training through integrating critical and Indigenous perspectives into postgraduate training, and specific training on professional bias, including fat bias. Furthermore, training perspectives require reorientation away from overemphasising mental processes towards an integration of mind-body in which the body is constituted as a site of meaning and identity. Psychologists can work towards a fat-friendly clinical practice by engaging with fat activist literature, weight-neutral models of health, and models of therapy that locate the client’s presenting concerns within broader cultural, political, and social contexts.</p>