Objective: The present study was conducted to find the effectiveness of training in metacognition and emotion regulation on the health behavior self-management of middle-aged overweight people and investigate the difference in the effectiveness of training based on metacognition and emotion regulation. Methods: This research was a semi-experimental study with pre-test, post-test, and follow-up and two intervention groups and one control group. The participants were people referring to weight loss clinics in Tehran. Convenience sampling was done by inviting on social networks. The total number of the research sample was 57 people who were placed in two experimental groups of training based on metacognition (18 people), emotion regulation (19 people), and a control group (20 people). All three groups were first pre-tested for self-management of health behavior. Then, the two experimental groups received the desired intervention; metacognition training and emotion regulation, and then, all three groups were subjected to a post-test using Walker and Pender’s lifestyle questionnaire, and the results of the two experimental groups and the control group were compared. Results: The results showed that metacognition (F(2, 34)=98.987, P<0.001, effect size=0.853) and emotion regulation (F(2, 36) =118.450, P<0.001, effect size=0.868) were effective in health behavior self-management and increasing health behaviors in general. There was no significant difference between their effectiveness (P>0.211). Conclusion: There are many theories to explain the principles used in health behavior and self-management to perform health behavior and promote and educate it. This research dealt with this category from the perspective of some of the principles of the third wave of cognitive behavioral therapy, and its results can be used in the formulation of health promotion training programs in healthcare systems. This research aimed to explain some of the individual and psychological aspects of health behavior. Specifically, the results of this research can be used in the prevention and treatment of overweight in institutions engaged in this field.