This study aims to evaluate the effects of an Acceptance and Commitment Therapy (ACT)-based group therapy program, combined with an ACT-based mobile app, on emotional eating, emotion regulation, and psychological flexibility in overweight individuals. Emotional eating is a condition in which individuals frequently use eating behavior as a coping mechanism for negative emotions.

Participants will be randomly assigned to intervention groups receiving ACT-based group therapy, ACT-based group therapy combined with an ACT-based mobile app, or a control group. The intervention will last six weeks and will include structured group sessions as well as mobile-based exercises, reminders, and coping strategies.

Outcome measures will include emotional eating, emotion regulation, and psychological flexibility. Assessments will be conducted at baseline, post-intervention, and during the follow-up phase. The findings of this study are expected to contribute to the development of accessible and effective interventions for emotional eating.

Research Objective The aim of this research is to examine the effect of acceptance and commitment therapy and acceptance and commitment therapy-based mobile application use on emotional eating, emotion regulation skills, and psychological resilience levels of overweight individuals. "Research Aim and Type The aim of this research is to examine the effect of acceptance and commitment therapy and acceptance and commitment therapy-based mobile application use on emotional eating, emotion regulation skills, and psychological resilience levels of overweight individuals.

The research was planned as a prospective, parallel, three-group (1:1:1) randomized controlled trial (RCT).

Research Variables Independent variables: Sociodemographic characteristics of the participants Dependent variables: Emotional eating, emotion regulation skills, psychological resilience Research Population and Sample The research population consists of individuals with a BMI of 25 and above living in Zonguldak province, Türkiye. The research sample consists of individuals with a Body Mass Index (BMI) of 25 and above who applied to the Nutrition and Dietetics outpatient clinics of Zonguldak Atatürk State Hospital and Zonguldak Karadeniz Ereğli State Hospital. The sample size of the research was calculated using G*Power 3.1.9.7 software. In the calculation made A three-group research design with an effect size of 0.815, a 5% margin of error, and a 95% power level is expected to reach a sample of 66 individuals. Considering the high power of the test and potential losses, the target sample size is 78 individuals. The sample size for each group is calculated as 26 individuals (KCT: 26, KCT+Mobile Application: 26, Waiting List: 26). Research data will be collected using an Information Form, the Emotional Eating Subscale of the Dutch Eating Behavior Questionnaire, the Difficulties in Emotion Regulation Scale (DERS), and the Acceptance and Action Form-II. The researcher has completed a 40-hour theoretical and practical training in 'Acceptance and Commitment Therapy (ACT)' organized by the Association of Contextual Behavioral Sciences and Psychotherapies and the Association of Cognitive Behavioral Psychotherapies. Additionally, the researcher has received four hours of training in the "Emotion Regulation Training Program" organized by Başkent Psychology Workshop and the Addiction Academy. Ethical committee approval required for the research (Date: (Received on 05.03.2025, Number: 36721). Permission was obtained from the Zonguldak Provincial Health Directorate for institutional permissions. Permission was obtained from the authors for the data collection forms used in the research. Individuals participating in the research will be informed in accordance with the Helsinki Declaration and their written and verbal consent will be obtained.

A group therapy intervention program was developed by the researcher in line with the literature. The program was planned with the aim of helping overweight individuals identify the problems they experience with emotional eating and emotion regulation, to define/understand the emotions that cause emotional eating, and to learn to live with these emotions instead of trying to prevent them. The relevant program was submitted to expert opinion, and after expert opinions, the necessary adjustments were made and the final version was prepared. In user-centered applications, the focus is on understanding and adapting to the users' perspective during the development phase of digital interventions. Including users in the process from the planning stage, conducting qualitative interviews, goes beyond evaluating usability and satisfaction and contributes to the creation of the psychosocial context of the intervention. Accordingly, in the second stage, for the design of the mobile application, data was collected from individuals experiencing emotional eating problems and from those with emotional eating, emotion regulation skills, and Experienced psychiatric nurses, psychiatrists, psychologists, and software developers with expertise in mobile application design were consulted regarding the content and design of the mobile application. In the third stage, storyboards were designed by the researcher based on the literature and the opinions received in the second stage. The mobile application included short psychoeducational content on emotional eating and emotion regulation, acceptance and commitment therapy-based emotion monitoring and awareness exercises that participants can use in their daily lives, data entry areas that allow for daily monitoring, progress charts that will enable them to track themselves with weekly analyses, and motivational messages to support and remind them to use the mobile application. After the completion of the mobile application design, it was presented again to expert opinions and the opinions of individuals experiencing emotional eating problems, and simultaneous adjustments were made in line with the suggestions received. Participants will be able to access the mobile application with their personal email addresses and passwords. The researcher will be able to track user data from their own administrator panel. Informed consent forms will be obtained from participants before the mobile application is launched.

Inclusion Criteria:

• Agreeing to participate in the study,
• Being between 18-65 years of age,
• Having a body mass index ≤ 25 (BMI ≤ 29.9),
• Being able to read and write,
• Having an iOS or Android smartphone,
• Having internet access,
• Having a home environment suitable for online sessions (having a computer/smartphone, internet access at home, the patient being able to be alone in the room during the session, etc.),

Exclusion Criteria:

• Having communication problems that would prevent the interview,
• Having a diagnosis of a mental disorder, including an eating disorder, that would prevent participation in the study, or having concomitant serious medical conditions that could potentially jeopardize study participation.
• Having undergone bariatric surgery. • Being on the waiting list for bariatric surgery.
• Being pregnant, breastfeeding, or planning to become pregnant within the next 6 months.
• Receiving therapy/counseling for emotional eating and emotion regulation problems,
• Using a mobile application for emotional eating and emotion regulation problems,

Individual participant data (IPD) sharing has not been decided at this stage. Due to ethical considerations, including participant confidentiality and informed consent procedures, data sharing plans will be evaluated after study completion. Any potential data sharing will involve de-identified data.