Insight can be impaired in individuals with an eating disorder and the nature of this impairment can vary. Although this topic has been the focus of several studies and reviews, methodologies used to assess insight have received less attention. A scoping review was conducted using a systematic search of articles before January 2021 to elucidate the methodologies used to assess insight in those with an eating disorder, with discussion of strengths and limitations. A total of 3089 studies were screened, and 24 quantitative studies which assessed at least one aspect of insight in individuals with an eating disorder were included in the review. Methods of assessing insight included coding of clinical notes, low scores on measures of self-report symptoms, direct assessment of insight, vignette, and self-report single-item questions. Insight into disordered eating symptoms was most frequently assessed. Most research used samples who were female, white, diagnosed with anorexia nervosa, and were seeking or receiving treatment. In designing future research and interventions, optimal methods used to assess insight should consider the research/clinical question, available resources, and the targeted demographic. Further, descriptions of which aspects of insight are being assessed should be considered in the interpretation of both current and future findings.