Abstract Introduction: One of the most practical psychological interventions in the field of managing mental disorders is acceptance and commitment-based therapy (ACT). The purpose of this research was to investigate the effect of acceptance and commitment-based therapy (ACT) on body image (BI) and mental health (MH) in male bodybuilding athletes of Izeh city. Materials & Methods: The method of this research is a quasi-experimental type of pre-test-post-test design with a control group. The statistical population of the research is all the male bodybuilding athletes of Izeh city, of which 30 people were selected as a sample using available and voluntary sampling in two experimental (15 participants) and control (15 participants) groups. The implementation of the treatment protocol based on acceptance and commitment was implemented in 10 sessions and each session lasted 90 minutes with the experimental group. Due to the Corona pandemic, intervention sessions were held in person and online. During this period, the control group did not participate in any specific exercise program. The library method was used to collect the background and theoretical foundations of the research, and the standard body image (BI) questionnaires of Littelton, Axsom & Pury (2005), Goldberg's mental health (MH) (1972), and Hayes' therapeutic intervention (2013) were used to collect data. The validity and reliability of the questionnaires were also confirmed. In order to analyze the data, Univariate covariance and Multivariate covariance statistical tests were used with the help of SPSS version 24 software. Results: The results of the research showed that there is a significant difference between the two experimental and control groups (at a 95% confidence level) after therapeutic interventions based on acceptance and treatment (ACT) in the variable of mental health (MH) (Partial Eta=0.56, Sig=0.001, P≤0.05); But there was no significant difference in body image (BI) (Partial Eta=0.07, Sig=0.085, P>0.05). Therefore, acceptance and commitment-based therapy (ACT) is effective on the mental health (MH) of the experimental group. Conclusion: Therefore, therapeutic interventions based on acceptance and treatment (ACT) improves the mental health (MH) of bodybuilding athletes. Therefore, managers and sport coaches can use this method of intervention in order to reduce the negative emotions of athletes.
