The results of the analysis of covariance showed that there was a statistically significant difference between ICBT, TAU, and WL groups (P < 0.001). Bonferroni post hoc test showed that ICBT, like TAU, significantly reduced BMI compared to WL. Consistent with this study, Abrahamsson et al. showed that CBT via a mobile video app is well accessible to patients, despite some technological issues, and that all participants in this study previously had little access to mental health services and high satisfaction with this form of therapy (
19). Zerwas et al. showed that the online format of CBT via chat groups was an effective treatment for bulimia nervosa although the course of recovery might be slower than in face-to-face therapy (
29). These results are not consistent with the findings of the study by Jacobi et al., who assessed web-based psychological services in women with bulimia nervosa. The results of this study showed no significant difference between the intervention and waiting list groups (
24).
The effectiveness of ICBT in reducing the BMI of individuals is highlighted in the monitoring of patients (an important aspect of CBT) that leads to weight loss during CBT. The patients are taught to supervise their food intake, emotions, feelings, overeating behaviors, and interpersonal problems (
28). Group members interact with the therapist to assess and identify barriers and concerns relevant to weight loss and modify their eating behaviors in CBT. Emphasis on modifying and changing overeating thoughts and behaviors of obese people and the importance of objectives and behavioral tasks motivate the people to follow a healthy diet by engaging in physical exercise to lose weight (
30). People also use cognitive restructuring techniques to explore and challenge their spontaneous thoughts versus fundamental beliefs. They learn to use problem-solving strategies to solve their diets and interpersonal problems (
28). The format of counseling sessions, its goals, use of various cognitive-behavioral techniques, and daily assessment of assignment in 42 therapy sessions enhanced the effectiveness of CBT. This issue justifies the effectiveness of ICBT in reducing BMI.
Obese people are ashamed of face-to-face meetings due to their physical appearance, which hinders psychological intervention (
12). They are constantly afraid of negative evaluations. However, ICBT is an online psychological intervention that does not need the physical presence of the patients who might be afraid of negative evaluations. The patient can anonymously benefit from psychological services. This is a unique feature of this form of therapy (
15). Besides, CBT also allows overweight and obese people to modify their eating behaviors and teach their minds to make a mental image of a thin person of themselves. This approach also helps people to choose a desirable diet and stabilize their weight by adopting mental and emotional strategies (
28). The high impact of ICBT interventions can be due to therapists' feedback during the treatment process. In this study, in comparison with the research on internet treatment programs, the therapist was present with the patient every day. Therefore, it seems that this type of treatment has the most therapeutic effect among internet-based therapies. In this study, using WhatsApp cyberspace, the therapist increased the likelihood of clients doing homework by sending daily reminders and monitoring the execution of assignments daily. In addition, the ability of the therapist to share the homework results in the group and receive feedback from the therapists and other people in the group was one of the factors that increased the likelihood of homework. This issue also justifies the effectiveness of ICBT in reducing BMI.
The results of the analysis of covariance of stress, anxiety, and depression after the intervention in the three groups showed that there was no statistically significant difference between the ICBT, TAU, and WL groups. However, due to the low observed power in stress, anxiety, and depression changes, the test is not accurate enough to detect significant differences, and the data should be interpreted with caution. These findings are not consistent with the findings of the study by Ebert et al., who showed the effectiveness of computer- and internet-based CBT in treating anxiety and depression symptoms in young people. They argued that computer- and internet-based CBT is a promising tool when the feasibility of evidence-based face-to-face CBT is questionable (
20). Tham and Chong reported the effectiveness of ICBT in reducing stress, anxiety, and depression (
21). Waite et al. also did not find promising results concerning the effectiveness of ICBT in the intervention group compared to the waiting list group (
22). Wright et al. also showed the ineffectiveness of this form of therapy in children with anxiety (
31). Evidence on the relationship of anxiety and depression with obesity was not promising. A positive relationship was found between anxiety/depression and being overweight. Another study in China showed a higher prevalence of depressive and anxiety symptoms in children and adolescents with overweight and obesity (
23). Another study showed that young adults who met the criteria for a depressive/anxiety disorder were almost 2.5 times as likely to be obese (
32). However, no significant relationship was found between anxiety/depressive symptoms and obesity. The logistic regression analysis showed that anxiety and depression variables could not predict obesity and overweight (
33).
The ICBT intervention could not significantly reduce anxiety and depression because of the COVID-19 pandemic in this study. Yang et al. also reported an increase in psychological disorders due to the COVID-19 pandemic, especially a dramatic increase in the incidence of anxiety, depression, and mental disorders in the general population (
34). The daily pursuit of news on the COVID-19 pandemic increases the risk of depression and anxiety in people (
35). These are similar to the clinical symptoms of anxiety and depression. Concerns about the risk of illness, future employment status, the income of the people and their families, and prolonged self-quarantining also increase the risk of psychological symptoms, including despair and hopelessness (
36). It was recommended to follow a healthy diet during the pandemic, which often people misinterpreted as no control over their weight. It was rumored that obesity boosts the immune system; nevertheless, Milner and Beck showed that obesity weakens the immune system (
37). A rigid dichotomy between obesity and normal weight during the pandemic increased the risk of anxiety and stress, although people controlled their weight. The COVID-19 pandemic has also increased the incidence of anxiety worldwide. Fear of death justifies human behaviors during the crisis (
38). Besides, ICBT was found to be ineffective in reducing stress, anxiety, and depression because of the persistence of these symptoms that cannot be treated with short-term therapy (six weeks). A few sessions were devoted to stress, anxiety, and depression, which necessitate the inclusion of more sessions to address these issues. There is also the possibility of incoherent implementation of ICBT in six months due to the online format of the therapy. This issue justifies the ineffectiveness of ICBT in reducing stress, anxiety, and depression.
5.1. Conclusions
The results showed that both ICBT and TAU significantly reduced body mass index with women with BMI ≥ 25, but there was no overall significant difference between in three groups in decreasing stress, anxiety and depression. Thus, the results in these cases should be interpreted with caution. Also, since internet-based cognitive-behavioral therapy is as effective as diet method, counselors, clinical psychologists and therapists can use ICBT method as an affordable, low-cost, practical and effective method for people with obesity.
5.2. Limitations
One of the limitations of this study was the use of self-report tool of the questionnaire, the sample size was limited to Neishabour city and its implementation coincided with the outbreak of Corona virus. In the participant selection phase, a number of individuals withdrew from the study despite their desire to participate in treatment due to concerns about using or connecting to the internet. It was not possible to control some variables, including the motivation of participants in recovery and active role in the group. Also, low test power in variables of stress, anxiety and depression, which in cases of results should be interpreted with caution.