Testing Just-in-Time Adaptive Interventions (JITAIs) to Prevent Goal Disengagement in Response to Weight Regain

BEHAVIORAL

JITAI Combined with psychological intervention

For six months, participants will receive a just-in-time adaptive interventions via a smartphone app immediately after they gain weight or they skip a weigh-in (according to a specific algorithm). Interventions will engage participants in mindfulness, acceptance, and self-compassion-based (MASC) strategies through different modalities (e.g., writing exercises, videos, audio reflections). They will take approximately 1-10 minutes. Participants will also attend an introductory workshop, during which they will receive the instructions weigh daily, learn the importance of quickly responding to weight regain, and be introduced to MASC strategies. They will also attend two booster workshops during the 6-month period.

BEHAVIORAL

Active Control

For six months, participants will receive weekly, automated messages via a smartphone app with reminders of standard behavioral weight control principles. Participants will attend an introductory workshop, during which they will receive instructions to weigh daily and learn the importance of responding to weight regain.

State negative affect

Time frame: Whenever participants skip a weigh-in or regain weight during the 6 month study period

Through ecological assessment surveys, participants will respond to a single item measuring their current negative affect.

State shame

Time frame: Whenever participants skip a weigh-in or regain weight during the 6 month study period

Through ecological assessment surveys, participants will respond to a single item measuring their current shame.

State Motivation

Time frame: Whenever participants skip a weigh-in or regain weight during the 6 month study period

Through ecological assessment surveys, participants will respond to a single item measuring their current feelings of motivation.

State Self-Efficacy

Time frame: Whenever participants skip a weigh-in or regain weight during the 6 month study period

Through ecological assessment surveys, participants will respond to a single item measuring their current self-efficacy.

Current confidence in the effectiveness of weight control behaviors

Time frame: Whenever participants skip a weigh-in or regain weight during the 6 month study period

Through ecological assessment surveys, participants will respond to a single item measuring their current confidence in the effectiveness of weight control behaviors.

State self-compassion

Time frame: Whenever participants skip a weigh-in or regain weight during the 6 month study period

Through ecological assessment surveys, participants will respond to a single item measuring their state self-compassion.

State mindfulness

Time frame: Whenever participants skip a weigh-in or regain weight during the 6 month study period

Through ecological assessment surveys, participants will respond to a single item measuring their state mindfulness.

State acceptance

Time frame: Whenever participants skip a weigh-in or regain weight during the 6 month study period

Through ecological assessment surveys, participants will respond to a single item measuring their state acceptance.

Self-serving interpretation of weight gain

Time frame: Whenever participants regain weight during the 6 month study period

Through ecological assessment surveys, participants will respond to a single item measuring their self-serving interpretation of the weight regain.

Daily Calorie Tracking (Yes/No)

Time frame: Whenever participants skip a weigh-in or regain weight during the 6 month study period

Whether participants log their calories (at least 800 calories) using a dietary tracking app that day (yes/no).

Daily MVPA

Time frame: Whenever participants skip a weigh-in or regain weight during the 6 month study period

Minutes of moderate-to-vigorous physical activity they engage in that day, as tracked by their Fitbit band.

Likelihood of weighing in the following day

Time frame: Whenever participants skip a weigh-in or regain weight during the 6 month study period

Likelihood that participants weigh themselves the following day on a wireless smart scale (yes/no).

Weight change

Time frame: End of treatment (6 months after baseline)

Using participants' weights from a wireless scale, we will calculate their percent weight change from the beginning to the end of the study period.

Intervention acceptability

Time frame: End of treatment (6 months after baseline)

We will record the percent of participants who indicate that they are "satisfied" or "very satisfied" with the program on an anonymous survey that they complete during their individual interview.

Calorie Tracking Frequency

Time frame: 6 months (duration of study period)

The number of days that participants logged their calories (at least 800 calories) using a dietary tracking app during the study period.

Average Weekly MVPA

Time frame: 6 months (duration of study period)

Average total minutes of weekly moderate-to-vigorous physical activity, as tracked by their Fitbit band, during the study period.

Frequency of Weighing In

Time frame: 6 months (duration of study period)

Total number of days that participants weighed themselves on a wireless smart scale during the study period.

What is a clinical trial?

A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.

Is it safe to participate?

Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.

Will I be compensated?

Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.

Will I receive a placebo instead of treatment?

When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.

Can I leave a trial if I change my mind?

Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.

How long does a clinical trial last?

Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.