Iranian Association for Intelligence and Talent Studies International Journal of Education and Cognitive Sciences 3041-8828 In Press 2027 06 01 Effectiveness of an Educational Package for Coping with Orthorexia Nervosa on Symptom Severity and Irrational Health Beliefs: An Experimental Study Effectiveness of an Educational Package for Coping with Orthorexia Nervosa on Symptom Severity and Irrational Health Beliefs: An Experimental Study 1 15 EN Journal Article 2026 06 23 <p><strong>Purpose: </strong>The present study aimed to evaluate the effectiveness of an educational package for coping with orthorexia nervosa in reducing orthorexia nervosa symptom severity and irrational health beliefs among adults attending bodybuilding clubs in Tehran.</p> <p><strong>Methods and Materials:</strong> This quasi-experimental study employed a two-group pretest–posttest design with a three-month follow-up. The statistical population consisted of adults aged 18–40 years who were regularly active in bodybuilding clubs in District 1 of Tehran. Using convenience sampling and subsequent screening, 72 eligible participants were selected and randomly assigned through block randomization to an experimental group (n = 36) and a control group (n = 36). The experimental group received the educational package for coping with orthorexia nervosa in ten 75-minute group sessions held twice weekly, whereas the control group received no intervention during the study period. Data were collected using the Orthorexia Nervosa Scale and the Health Irrational Beliefs Scale at pretest, posttest, and three-month follow-up. Data were analyzed using repeated-measures analysis of variance and Bonferroni-adjusted pairwise comparisons in SPSS version 26.</p> <p><strong>Findings:</strong> Repeated-measures analysis showed significant group × time interactions for orthorexia nervosa symptom severity, F(2,140) = 52.79, p &lt; 0.001, partial η² = 0.430, and irrational health beliefs, F(2,140) = 29.34, p &lt; 0.001, partial η² = 0.296. In the experimental group, orthorexia nervosa symptoms decreased significantly from pretest to posttest (p &lt; 0.001) and remained significantly lower at follow-up (p &lt; 0.001), although a small significant increase occurred from posttest to follow-up (p = 0.033). Irrational health beliefs also decreased significantly from pretest to posttest and follow-up (both p &lt; 0.001), with no significant difference between posttest and follow-up (p = 0.574).</p> <p><strong>Conclusion:</strong> The educational package was effective in reducing orthorexia nervosa symptom severity and irrational health beliefs, and most of the observed improvements were maintained over the three-month follow-up period.</p> https://www.journalecs.com/index.php/ecs/article/download/489/422