1. Introduction
besity is often caused by over-consumption of food, physical inactivity and genetic susceptibility [1, 2]. Obesity is one of worldwide preventable causes of mortality, which has increased in adults and children [4]. World Health Organization (WHO) considers it as one of the most serious public health problems in the 21st century [6]. The WHO predicts that overweight and obesity may soon replace the traditional public health concerns including undernutrition and infectious diseases as the main cause of poor health [7]. There are parallels in the areas of the brain that are responsive to food and drug use [19]. The abuse of substance or palatable foods produces eating patterns similar to that of dopamine-related neural activation [20]. Food addiction includes craving, drinking and overeating. Behavioral symptoms of food addiction appear in patients with bulimia nervosa, binge eating disorder, obesity, and even in the normal population [22, 23]. The Yale Food Addiction Scale (YFAS) is a reliable psychometric tool that has validity to be used in clinical and non-clinical samples [26, 34]. It can be used to diagnose people with or without food addiction and assess the symptoms of eating disorders. The YFAS has been translated into several languages and is widely used in many studies [12].
2. Methods
This is a descriptive cross-sectional study. The study population consisted of all people who are suspected to have food addiction refereed to the Novin Food Center in Isfahan, Iran in a period from February to May, 2018. By using a convenience sampling method and using formula, 180 people including 98 with food addiction and no control over their eating based on the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) assessed by a nutritionist, and 67 normal people were participated in this study. They were asked to complete the Persian YFAS questionnaire. The descriptive statistics (percentage, frequency, mean and standard deviation), were used for describing results, and the multivariate ANOVA was used to examine the research hypotheses. To examine the psychometric properties of the Persian YFAS, we used Cronbach’s alpha coefficient to assess internal consistency; confirmatory factor analysis to determine the construct validity; and multivariate ANOVA to determine its discriminant validity.
3. Results
In testing the goodness-of-fit of the proposed model, the Root Mean Square Error of Approximation (RMSEA), Comparative Fit Index (CFI), IFI, Normed Fit Index (NFI), Goodness-of-Fit Index (GFI), and Adjusted Goodness-of-Fit Index (AGFI) with the values of 0.21, 0.965, 0.915, 0.982, 0.953, 0.954 respectively, showed the appropriate fit of the model which indicates the construct validity of the Persian YFAS. In testing discriminant validity, the significance level for all subscales was less than 0.05 indicating that there is a significant difference between the two groups in terms of all YFAS subscales, where the mean scores of all subscales and the mean total score were significantly lower in samples with food addiction than in healthy samples. In food addiction and its subscales, opinion of the samples was less than average level (<3). Also, all sub-scales have an acceptable factor loading. The results show that the correlation between items and subscales was rather high and significant. The total Cronbach's alpha value for the reliability of the entire YFAS questionnaire was reported 0.87. The Guttman split-half coefficient value was also higher than 0.7. These indicate the reliability of the Persian YFAS is satisfactory.
4. Discussion
In this study, the YFAS questionnaire was validated for the first time on Iranian population to be used by Iranian scholars and clinical experts for the diagnostic or research purposes. In examining the reliability of the Persian YFAS, it was found out that the numbers of symptoms and diagnoses are stable over a period of 20-26 days and, as expected, there was moderate to high correlation between the food addiction and the eating disorders (the number of symptoms and diagnoses) indicating that the Persian YFAS has a high convergent validity. In further studies, more structured questions (such as dietary status) should be used to evaluate changes in eating habits and lifestyle behaviors over time. Eating disorder is a major concern in Europe and America, Especially among female adolescents. In Iran, food addiction has caused some physical problems, such as cardiovascular disease, type 2 diabetes, and cancer as well as the increased rate of mortality and treatment costs. Given the adverse effects of eating disorder and the need to prevent its complications, results of this study can be helpful in psychiatric interviews due to the lack of bias in the repeated measurements and using a larger sample size. Due to the lack of time, it was not possible to determine test-retest and responsiveness of treatment .

Ethical Considerations
Compliance with ethical guidelines
The participants were fully aware of the study objectives and had consent to participate in the study. They were allowed to leave the study at any time.

Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Authors contributions
All authors contributed in designing, running, and writing all parts of the research.

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgements
The authors would like to thank the treatment staff of Novin Food Center and all participations for their valuable cooperation.


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