The adaptation of orthorexia nervosa scales, and the investigation of relations of OCD, eating disorders, depression, anxiety and stress, general psychological symptom levels, health anxiety, body image, and self-esteem with quantitative and qualitative methods

Orthorexia nervosa (ON), defined by Bratman (1997), is a disorder that expresses the obsession with healthy eating and that people restrict their diet according to the quality of the food, which is not yet included in the diagnostic manuals. To understand ON more deeply, this thesis study consists of 3 main stages as a mixed methods research. In the first stage, adaptation of the Eating Habits Questionnaire, Düsseldorf Orthorexia Scale, Barcelona Orthorexia Scale and Orthorexia Nervosa Scale into Turkish, and determining the common factors of ON scales were aimed to increase our understanding of what ON is. In the second stage, examining the relationships between ON and OCD, eating disorder, depression, anxiety and stress, psychological symptoms, health anxiety, body image, and self-esteem variables were intended. In the third stage, semi-structured interviews were conducted with the participants with high ON symptoms, and it was aimed to reveal the themes of what a healthy diet is for these people through interpretive phenomenological analysis. In the first stage, 726 participants took part and the scales were found to be reliable and valid in measuring ON. The common factors obtained from the scales were "negative emotions", "deterioration in daily functionality", "importance given to healthy eating habits", "exaggerated preoccupation with healthy eating". In the second phase, 556 participants were involved and OCD, health anxiety, and eating disorder symptoms were consistently associated with ON; no consistency was observed in the relationship of ON with self-esteem and body image. In the stepwise regression analysis, the level of eating disorder symptoms was the strongest predictor of ON. In the interviews conducted with 11 participants with a high ON tendency, 5 main themes emerged: "the meaning of healthy eating", "etiology and maintaining factors", "control, power and autonomy", "comparisons" and "daily functionality". The findings were discussed in the light of the literature.