1. Introduction
In theories of health behavior, thinking (attitude and mental criteria), emotion, and decision-making are common and one of the basic principles of health behavior theories. Therefore, attitude and mental and cognitive criteria are the main factors in performing or abandoning a healthy behavior (Schwarzer, 2008). Consequently, one of the issues that are emphasized in all models and theories is that in order to change behavior, cognition must be changed, and in other words, modification of the content of thinking is essential, which seems obvious due to the formation of these theories in the atmosphere of the second generation of cognitive behavioral therapies. According to the assumptions of the third-wave cognitive behavioral therapies, such as the assumption that the main source of psychological damage is the style and the way a person faces thinking and emotion, this question is raised to make decision to perform a health behavior and continue with it: Are these assumptions of the third-wave cognitive behavioral therapy effective? 
According to many researchers, the current theories that explain health behavior have many strengths and weaknesses. For example, Sharma (Sharma, 2015) is one of the researchers who worked in this field. According to him, these theories and models do not lead to the maintenance of the behavior and do not have constant predictive power. They are too comprehensive and impractical, but not economical, and often describe behavior (Barati & Abbasi, 2017). The term, metacognition, was first proposed by Flavell (Flavell, 1976). He considered metacognition knowledge about cognition. The beliefs that people have about their thinking are called metacognition. The reflection of humans on their mental processes, and thinking about thinking is called metacognition. Metacognition has been regarded as a means of manipulating and organizing cognitive processes (Abbabaf, 2008; Seyed Mohammadi, 2018). In general, metacognitive therapy is based on this fundamental principle that psychological disorder persists due to the effects of thinking style, i.e. cognitive-attentional syndrome in emotional experiences and knowledge(s) (Wells, 2015). This model offers several methods that focus on putting aside the cognitive syndrome of attention, modifying metacognitive beliefs, shaping a different way of experiencing, and relating to internal events (Wells & Sembi, 2014). It is a process, in which people adjust their emotions consciously and unconsciously in order to best respond to the needs and changes of their environment (Gross, 1998). Emotion regulation is defined as the process of initiating, maintaining, adjusting, or changing the intensity or persistence of a person’s internal emotion. Also, emotion regulation is related to social, psychological, and physical processes to achieve one’s goals. Six methods (strategies) of emotion regulation are reinterpretation, acceptance, problem-solving, avoidance, rumination, and emotion controlling (suppressing). The first three methods are effective and the second three methods are ineffective and lead to psychological harm (Mohammadi et al., 2015). Emotion regulation training is considered a basic element in most of the new cognitive behavioral therapies known as the third-generation (Mohammadi et al., 2015). Emotion regulation and well-being are two interrelated concepts from different aspects. These two concepts are triggered by similar brain regions that are involved in interactive behavior with others. In addition, these two affect optimal and non-optimal performance, psychopathology, social isolation, and physical symptoms (Nykliček et al., 2011). The relationship between variables, such as metacognition or emotion regulation with a health behavior or the effect of an intervention on a disease related to an unhealthy lifestyle, such as overweight, has been assessed (Allen &Woolfolk, 2010; Morawetz et al., 2020; Mucha et al., 2020). In this research, the management of health behavior, or in other words, a set of health behaviors, was discussed.
Addressing the issue of health behavior from the point of view and with the presuppositions of other approaches plays an important role in promoting health as well as managing the treatment of chronic diseases and increasing the ability of a person to maintain and improve health (Mirzapour et al., 2021). Therefore, finding factors that cause failure or success in self-management can be considered in developing comprehensive health promotion programs.
Today, one of the most critical trends and plans of healthcare systems, health education, can increase health literacy to encourage people to perform healthy behavior and self-management in three stages: Prevention, treatment, and prevention of recurrence in both chronic and acute diseases. Similarly, in the recent COVID-19 epidemic, the most effective human weapon against the spread of this disease was the daily behavioral changes of the people. There are many theories to explain the principles used in health behavior and self-management to perform health behaviors and promote and educate them. This research deals with this category from the perspective of some principles of the third-wave cognitive behavioral therapy. Its results can be used in developing health promotion training programs in healthcare systems.
 The general aim of the research was to compare the effect of metacognition training and emotion regulation on the self-management of health behavior of overweight middle-aged people.. Based on the main hypothesis of this research, training based on metacognition and emotion regulation is effective in the self-management of health behavior in overweight middle-aged people. The difference between this research and similar research is that in addition to examining the effectiveness of two approaches of the third-generation cognitive behavioral therapies, it also compares the effectiveness of these two methods, and they can create a new model in health behavior theories.

2. Materials and Methods
This research was a semi-experimental study of pre-test post-test and follow-up types with intervention and control groups.
Sampling was done using the convenience sampling method by inviting people to five weight loss clinics. The participants were people referring to weight loss clinics in Tehran. The process of sample selection grouping and intervention was carried out from November 2021 to February 2022 in Tehran. The initial stage of sampling was in person and the intervention was done online due to the COVID-19 epidemic in eight sessions and each session lasted for one hour and a half. The inclusion criteria were: 1- The age range was between 45 and 65 years old (middle age range) according to Erikson’s theory (Seyed Mohammadi, 2018). 2- Body mass index (BMI) was between 25 and 29 kg/m2 (overweight) (Sanderson, 2018). 3- The minimum level of education was the graduation from the secondary school.
Exclusion criteria were: 1- Medical history of visiting a neurologist and taking neuropsychiatric drugs, 2- A history of taking corticosteroids, 3- A history of drug and stimulant abuse or dependence on sleeping pills or alcohol dependence, 4- A history of childhood obesity before ten years old, 5- Overweight caused by physical diseases, such as diabetes, hypothyroidism, Cushing’s syndrome, growth hormone disorder (nanism), and polycystic ovary syndrome.
The number of samples: The sample size for each intervention and control group was considered to be 20 people. Due to the uncertainty of the sample variance, according to Dr. Delavar’s recommendation in his book (Delavar, 2019) (the topic of sample size), which mentions the sample size of at least 15 people in the experimental research, the sample size for each intervention and control group was considered to be 20 people. Two people in the metacognition group and one in the emotion regulation group were excluded from the study (one of them due to unwillingness to continue the sessions and two due to illness and absence of more than two sessions). The total number of the research sample was 57 people who were placed in two experimental groups receiving metacognition (18 people) or emotion regulation (19 people), and a control group (20 people).
The groups in the study were tested in three phases: Pre-test, post-test, and follow-up. For all three groups, first, a pre-test of self-management of health behavior was performed. 
Walker and Pender’s health-promoting lifestyle questionnaire (Walker et al., 1987) measures health-promoting behaviors in six dimensions: Nutrition, exercise, health responsibility, stress management, interpersonal support, and self-actualization and questions show positive actions and perceptions in order to increase health and well-being. The validity and reliability of this questionnaire, which has been used in many types of research in the world and Iran, is acceptable. The Cronbach’s α for the whole scale is 0.922; Cronbach’s α for the subscales range from 0.702 to 0.904 (Walker et al., 1987). The validity and reliability of the Persian version of this questionnaire were investigated in a research (Mohammadi Zeidi et al., 2011). In this study, the Cronbach’s α coefficient for the whole instrument was 0.82 and for subscales was from 0.64 to 0.91. All items had acceptable correlations (greater than 0.34).
Then, the intended intervention, which was metacognition training and emotion regulation, was performed, and in the end, the three groups were subjected to the post-test of health behavior self-management. Finally, the results of the experimental groups and the control group were compared two by two. The intervention was conducted online and the summary of the intervention in the meetings is mentioned in Table 1 and Table 2.






3. Results
First hypothesis: Training based on metacognition is effective in health behavior self-management of overweight middle-aged people.
Second hypothesis: Education based on emotion regulation is effective in self-management of health behavior among overweight middle-aged people.
Repeated-measures analysis of variance (ANOVA) was used to test these hypotheses and the scores of the tests were compared in three stages: Pre-test, post-test, and follow-up. Before conducting the main tests, descriptive indicators and presuppositions of these tests were checked.
Descriptive findings of the hypotheses
Table 3 shows the mean and standard deviation of the self-management variable in the experimental groups in the pre-test, post-test, and follow-up stages.
Table 3 shows that the mean score of self-management of health behavior increased in the post-test and follow-up phase compared to the pre-test phase.



Assumptions of the hypotheses analysis
A) Normality of data distribution: Shapiro-Wilk test was used to check the normality of data distribution. The Shapiro-Wilk values related to the self-management in both groups in all three stages of pre-test, post-test, and follow-up were insignificant at the 0.05 level. This shows the normal distribution of data in all three stages.
B) Presumption of sphericity: Mochli’s test was used to check this presumption. The result of this test showed that there was a presumption of sphericity in the data in the meta-cognition (P=0.766, x2=0.533) and emotion regulation (P=0.159, x2=3.68) groups.
Table 4 shows the results of repeated-measures ANOVA for the self-management.



Based on the results obtained from repeated-measures ANOVA, there was a significant difference in the mean score of self-management of health behavior in the pre-test, post-test, and follow-up in the experimental groups. The value of Eta-squared shows that about 85% of the variance of the self-management was explained by metacognition-based training and shows that about 87% of the variance of the self-management was explained by education based on emotion regulation. To determine this significant difference in which stage, the Bonferroni post hoc test was used with type 1 error correction. The results of the pairwise comparison of the stages of the research are reported in Table 5.



Table 5 indicates that the difference in the mean score of self-management of health behavior in the pre-test stage compared to the post-test and pre-test stage and the follow-up was statistically significant. But there was no significant difference between the post-test and the follow-up stages. This shows that the results obtained during the follow-up stage were stable.

4. Discussion
The results showed that the mean difference in the health behavior self-management scores in the pre-test than in the post-test and in the pre-test than in the follow-up in both metacognition and emotion regulation training groups were statistically significant. But there was no significant difference between the post-test and the follow-up. Based on this result, metacognition and emotion regulation training is effective in improving health behavior.
The result about metacognition is in agreement with previous results (Castro Muñoz et al., 2021; Lenzo et al., 2020; Nameni et al., 2017; Palmieri et al., 2021; Cinar & Schou, 2014) and the result about emotion regulation training is in agreement with that of other studies (Miller et al., 2018; Morawetz et al., 2020; Pachón-Basallo et al., 2021; Steward et al., 2019; Gomez & Perez, 2020; Isasi et al., 2013; Ferrer & Mendez, 2018; Babaei et al., 2021). To explain the results obtained about metacognitive training, it can be said that according to the theory of self-regulation of executive function (S-REF), metacognitive training affects self-regulation through negative relationship with cognitive attention syndrome (CAS) and self-regulation has a positive relationship with self-efficacy (Kaplan, 2008; Salari Far & Mazaheri, 2010; Cera et al., 2013; Pour vakhshoori et al., 2011). The self-regulation structure enables people to develop their goal orientation in the learning process and provides opportunities for them to actively evaluate and monitor their thought processes. This can increase self-efficacy, which plays an essential role in influencing the adaptation, initiation, and maintenance of health behaviors as well as curbing unhealthy practices (
; Samadi et al., 2019). The relationship between emotion regulation and health behaviors can be examined from two aspects: Addictive behaviors and self-efficacy. Addictive unhealthy behaviors are actually an inefficient method of emotion regulation, which is called avoidance. When a person uses effective methods of emotion regulation, he will not need using the avoidance method; thus, performing these behaviors will decrease (Steward et al., 2019). On the other hand, emotion regulation increases self-efficacy. Proper emotion regulation makes a person use better coping methods, such as problem-solving in stressful cases. Also, emotion regulation improves a person’s social behavior because being receptive toward others and being extroversion requires reducing negative feelings and mental ruminations in social communication. Therefore, by receiving positive feedback from problem-solving and appropriate social behavior, a person will have a higher self-efficacy and will be more successful in starting and continuing healthy behaviors. Regarding the effectiveness of these two methods (Gutiérrez‐Doña et al., 2009; Javidan et al., 2018), there was no significant difference between their effectiveness. In explaining the reason for this similarity, the researcher searched up to 40 pages in the Google engine and did not find any similar research, and therefore, he put forward hypotheses, such as:
1- Although the used tool to assess health behavior self-management has sufficient validity, has no sufficient sensitivity to measure the difference in the groups; therefore, there were differences in the both intervention groups (metacognition and emotion regulation groups), but this difference was lower than the sensitivity of the measurement tool and both groups showed the same results. 2- Another more probable hypothesis is that both intervention methods, i.e. metacognition and emotion regulation, influence health behavior through another variable; for example, self-efficacy. Therefore, both intervention methods caused a change in another variable, which led to the improvement of health behavior. and this assumption can be another research field. 3- Two methods were equally effective.

5. Conclusion
Factors or obstacles against behavior change are one of the most fundamental psychological issues with a specific hypothesis to be explained by all psychological approaches and trends. Behaviors related to health and lifestyles are no exception to this rule. 
In health behavior theories, various viewpoints and theories are expressed in explaining the cause of existence and the formation or change of behavior, but the change and modification of thinking is one of the issues that are emphasized in all models and theories in order to change behavior. It is caused by the formation of these theories in the atmosphere of the second wave of cognitive and behavioral therapies. With the formation of the third-wave cognitive-behavioral therapies, concepts, such as acceptance, attention, awareness, and observation of emotion and non-avoidance expressed in the form of different approaches and techniques, including metacognition and emotion regulation, play an important role in improving cognition and behavior modification. Therefore it seems that the concepts of the third-wave theories of cognitive-behavioral therapies should play a more important role in the basic theories of health behavior and this type of view may lead to the formation of new models and theories in health psychology.
Limitations
1- One of the major limitations of this study is its cross-sectional nature, although a 3-month follow-up study was also conducted, long-term studies are needed to check the stability of the intervention over a longer period. 2- The limitation of the causal explanation of correlational studies is also one of the limitations of this research. 3- The tool used in this research was based on self-report, and this is one of the limitations of this research that needs to be noted.
Suggestions
1- The effect of other approaches of the third-wave cognitive behavioral therapies on the promotion of health behaviors should be evaluated and investigated.
2- Health behaviors were investigated with a general title and a set of several behavioral fields, such as sports, nutrition, etc.; it is suggested that each behavioral field be researched alone.
3- The results of this research can be used in the preparation of protocols for the prevention and treatment of overweight in relevant institutions.

Ethical Considerations

Compliance with ethical guidelines
The present study was confirmed by the Ethics Committee of Islamic Azad University, Tehran Medical Sciences (Code: IR.IAU.TMU.REC.1400.228).

Funding
This study was extracted from Mehdi Mehraban Eshtehardi's PhD dissertation, approved by Islamic Azad University, Rudehen Branch.

Authors' contributions
Conceptualization, methodology and supervision: Narges Babakhani and Peyman Hassani Abharian; Writing the original draft, data collection and data analysis: Mehdi Mehraban Eshtehardi; Review & editing: Mehdi Mehraban Eshtehardi and Narges Babakhani.

Conflict of interest
The authors declared no conflict of interest.

Acknowledgments
The authors thank the respectable participants. 


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