The purpose of the 6-month micro-randomized Trial (MRT) is to optimize a just-in-time adaptive intervention (JITAI) for dietary lapses by evaluating the effects of 4 theory-driven interventions on the proximal outcome of dietary lapse as compared to active and inactive comparators. The proposed JITAI has been extensively piloted, and will now be executed using a well-known NIH-funded mobile platform (PiLR Health). Prior to commencement of the main trial, a small group of participants will be recruited to iteratively pilot the below-described procedures for 3 months. These data are for piloting/testing only and will not be used in the analysis of primary outcomes. Participants in the main trial (N=159) will receive 3 months of online behavioral obesity treatment (BOT) + JITAI followed by 3 months of JITAI-only. The MRT includes sequential randomization to intervention options each time the JITAI identifies heightened lapse risk. The primary outcome is dietary lapse (assessed via repeated surveys called ecological momentary assessments \[EMA\]). The secondary outcome is objectively-measured eating characteristics (via wrist-watch device at assessments). The investigators will also assess contextual moderators (i.e., location, time of day, active BOT/follow-up, trigger type) for the study's exploratory aim. JITAI engagement, satisfaction, and weight will be used for descriptive purposes.

Participants will be recruited on a rolling basis (\~6-7 participants/month) until the target N=159 is reached. Participants will be recruited via advertisements in local media (e.g. newspapers, radio) and targeted online advertising (e.g., Google AdWords); flyers and advertisements posted in waiting rooms and exam rooms in primary care offices, informational materials made available as part of the health and wellness program for employees in the Lifespan heath system and hospital network (an approach used in a previous trials); and direct mailings. Minority participation will be increased via ads in newspapers with high circulation in minority communities. Recruitment flyers will also be sent to agencies serving minority groups. The investigators will use online advertisements on local websites that are popular with men and minority groups. The investigators consistently find that these approaches maximize minority and male recruitment.

All following procedures described will be offered both in-person at the research center, or remotely via the video chat forum Zoom. The remote option is in response to the COVID-19 pandemic. Participants who choose to attend in-person assessments will use self-report screening procedures consistent with hospital policy to ensure that the participant has not been recently or is currently ill. Rigorous sanitization procedures will be used for equipment and office space pre- and post-assessment.

Interested individuals will be initially screened for eligibility via REDCap, a Lifespan secure website. If a participant appears to be eligible based on their survey responses, they will receive a follow-up call from the research team to confirm eligibility, describe the study in more detail, and schedule an orientation meeting. If they are not eligible, they will receive a message indicating that they are not eligible for the study and directed to contact us if they wish to receive referrals for other weight loss programs. Those who are eligible will be invited to an orientation, either in-person at the research center or via the online video chat forum Zoom, where the study will be described and informed consent obtained. Individuals who decide to complete the orientation via Zoom will be sent a consent form to their home address before the call. Only after the consent form is signed and returned will any further study procedures be completed. If consent is not given, participant contact information will be immediately removed from the system. After consent is obtained, participants will complete baseline questionnaires, either by paper surveys or using Lifespan's secure REDCap website, and they will complete self-reported logs of what they eat and drink and EMA for 1 week before their baseline assessment. If a participant elects to use a paper questionnaire and does not wish to be present at the research center, the questionnaire will be sent to the participant's home address. Participants must complete \>70% of EMA surveys and 7 days of dietary self-monitoring to move forward with the remainder of study procedures.

Following consent and successful completion of baseline procedures, participants will attend a "kick-off" session (either in-person or remotely) to assist them in using the intervention tools. Participants will be given access to an online BOT (described further in the Intervention section) for 3 months, with an additional 3-month no treatment follow-up. They will also be asked to use the JITAI for the entire 6-month study period. The JITAI operates through PiLR Health, and will utilize ecological momentary assessment (EMA) to repeatedly assess lapse triggers and dietary lapses. The EMA survey responses are immediately uploaded to a HIPAA-compliant server, where a previously-validated predictive algorithm determines if the participant may be at risk for a lapse based on what they reported. When a participant is determined to be at risk for a lapse after completing an EMA survey, the PiLR Health system server will micro-randomize the delivery of intervention. The randomization is independent of prior randomizations and the participants' responses to previously delivered interventions for lapse. Based on the investigator's prior research developing this JITAI, the algorithm predicts heightened states of lapse risk approximately once per day. The once/day estimate is representative of an average across participants and the investigators have demonstrated there is substantial individual variability to these data; heightened states of lapse risk can range from 2.75/week to 12/week and fluctuate over time. As such, while the estimated average is once per day, the prediction algorithm within the proposed JITAI ensures that intervention is provided in exact moments of individual need - which is not static within or between individuals - thus reducing participant burden and improving potency of intervention. The study methods are therefore a considerable improvement to providing general daily reminders. Based on these data, intervention options will be randomized an average of 180 times for each participant. The theory-driven intervention conditions, which have empirical support, include: (a) education to promote awareness of lapse triggers; (b) self-efficacy; (c) motivation; \& (d) self-regulation skills. Given the primary aim of comparing the immediate, proximal effect of intervention (as compared to no intervention), interventions will be randomized based on the following probabilities: 0.4 no intervention (inactive control), 0.12 to generic risk alerts (active control), 0.12 to Enhanced Education, 0.12 to Self-efficacy, 0.12 to Autonomous Motivation, and 0.12 to Self-regulation. As such, a given participant will receive no intervention at approximately 72 randomization points over the study and 107 (\~21-22 each) randomization points will be divided equally among the remaining 5 intervention options. All JITAI interventions are described in the Intervention section

In addition to data they are providing through the JITAI, participants will complete 3 total assessments with a research assistant (who does not need to be blinded due to sequential randomization) at baseline, 3, and 6 months. During the baseline assessment, height, weight, demographic information and weight history will be collected either by a study staff, cellular scale, or self-report. Objective data collection will be the priority, so if a participant elects to attend their assessment via Zoom, cellular scales may be mailed to the participant's home address. Participants will be asked to wear a wrist-watch device (called an Actigraph) to measure eating behavior for two weeks following the baseline appointment. The participant will be given the Actigraph device in-person during the baseline assessment, or by mail to their home address if they choose to attend the assessment via Zoom (the device will be mailed back to the study team or dropped off in-person). Also, during the baseline assessment, participants will be provided with a calorie and physical activity goal, overview of the program, and tutorial for using the smartphone app and online program. The participants will be asked to complete similar assessments at 3 months and 6 months.