Childhood obesity within the United States has been a growing concern over the past number of years, and if not addressed, leads to detrimental health outcomes for youth as they move into adulthood. The literature suggests that over-eating, especially when framed in terms of food addiction, plays a key role in this epidemic; however, treatment options are time intensive, posing a profound logistical barrier for both the child and parent and often limits or prevents engagement. As research within the field of mHealth has grown, technology-based interventions have gained traction, specifically interactive smartphone applications (apps). Displacement theory, although not new, has been understudied yet provides a strong explanation and treatment plan for addictive type behaviors. The core of this theory posits that problems which one feels they cannot face nor avoid leads to repetitive and irrepressible behaviors; however, if a healthy coping behavior can be learned and utilized, then the unhealthy behavior will cease. The theory lends itself well to being adapted into an mHealth format, making it more easily accessible and more widely used. Grounded in displacement theory, the proposed study aims to develop an app-based weight loss intervention for adolescents with obesity. Information gained regarding the feasibility and acceptability of such an intervention can potentially be replicated and applied to other populations with various addictive behaviors. Helping those with addictive behaviors in a format that has little to no logistical barriers can have a substantial impact on public health. A novel smartphone app will be designed by key stakeholders and refined through the course of the study. 38 total adolescents (14-21 years old) with %BMIp85 will be recruited via various sources (e.g., clinic referrals, flyers, social media advertising) to participate in one of two stages of the study: the beta testing stage or the trial stage. Beta testing will enroll one group of eight teens to test the app for three weeks; participants will be assessed in-person pre- and post-intervention. After each group, the app will be modified to incorporate their feedback in order to promote youth engagement. The trial stage will enroll 30 adolescents to participate in a four-month intervention; participants will complete three assessments, baseline, post-intervention (both in-person) and one-month post-intervention (either in-person or virtually). The study will examine engagement and satisfaction with the app, as well as the intervention's impact on clinical outcome measures (weight and BMI, diet and snacking, and addictive behaviors related to food and substance use) and potential mediators/moderators (motivation for change, perceived stress, and distress tolerance).

Aim 1: To develop a smartphone app aimed at reducing over-eating behaviors among adolescents with obesity based on the theory that addictive behaviors are driven by a displacement mechanism in the brain. Based on displacement theory, over-eating and associated weight gain are the result of situations that individuals feel they cannot successfully face nor avoid. App development will include input from various stakeholders including obesity medicine specialists, pediatric clinicians, psychologists, and individuals living with obesity.

Aim 2: To test and modify the app through an iterative process; one group of 8 teens will beta test the app for three weeks each and provide quantitative and qualitative data used to make changes which facilitate usability and engagement.

Aim 3: Evaluate the feasibility of the app among 30 adolescents (15F;15M) to identify barriers and facilitators to its implementation. We will measure (a) adherence to daily app use with particular focus on the participant's identification of a "Dread List" and the implementation of "Action Plans" aimed at ameliorating stressful situations identified in the list, (b) quantity (#hours per participant) and quality (type and frequency of team member engagement per participant) of support required to promote adherence, (c) satisfaction with the app intervention (qualitative assessment of satisfaction rates, exit interviews, reason for dropouts), and (d) assessment burden. This knowledge will inform the refinement of the intervention for the subsequent larger trial.

Aim 4: Preliminary assessment of the impact of app engagement and usage on clinical outcome measures (weight and BMI, diet and snacking, and addictive behaviors related to food and substance use) and potential mediators/moderators (motivation for change, perceived stress, and distress tolerance).

Hypothesis 1: More engagement with and use of the app will be related to better clinical outcomes; specifically, participants more engaged in the app will show reductions in weight and BMI, over-eating behaviors (self-reported diet recall and snacking), and overall addictive behaviors.

Hypothesis 2: Participants with greater motivation, lower perceived stress, and greater distress tolerance at intake will engage more with the app and have better clinical outcomes; also, those who engage with and use the app more will exhibit increased motivation, lowered perceived stress, and greater distress tolerance which will in turn result in better clinical outcomes.

Inclusion Criteria:

1. 14-21 years old
2. Has an iPhone or are willing to use a study iPhone
3. Ability to read and speak English
4. Endorsement of one of the three items listed below on the five-item S-weight questionnaire indicating motivation for change During the last year I haven't done anything to lose weight but I'm planning to do something over the next 30 days.

I've been making an effort to lose weight (by dieting1 and/or exercising2) for less than 6 months.

I've been making an effort to maintain my weight (by dieting1 and/or exercising2) for more than 6 months.

6. Body mass index [BMI] ≥85th percentile for age and gender

Exclusion Criteria:

1. Any psychiatric condition and/or developmental delay which would require immediate or ongoing treatment that would make study participation difficult or harmful
2. Parent/guardian-reported physical, mental of other inability to provide consent or refusal to provide consent for minor children
3. Self-reported diagnosis of Prader-Willi Syndrome, brain tumor, hypothalamic obesity, or other diagnosis associated with obesity
4. Concurrent participation in an alternative weight loss intervention
5. Participation in the study team's previous app weight loss studies (exclusion for trial but not beta testing participants)