She recommended using a distorted eating questionnaire and including people who has the most distorted eating normal disordered population (not clinical). Recruit as many people as you can, just only those who have the highest score on the scale to include in the research. Explore which questionnaires we could use to measure self-criticism, mental well-being, and criteria for analysis. She also has included a PDF of the Eating Disorder examination questionnaire (EDEQ), this is a well validating questionnaire that we may want to use in your research. We could either split participants into high and low scorers and do a comparison, or just include those who score the highest to get a close to clinical sample. We also should start thinking about which questionnaires we will utilise for other outcome measures- the journal articles you have already included will be a good start for this.
