NCT05625061

Just-in-time Adaptive Intervention Messaging in a Digital Weight Loss Intervention for Young Adults

A Micro-randomized Trial of JITAI Messaging to Improve Adherence to Multiple Weight Loss Behaviors in Young Adults

• Status: Completed
• Phase: N/A
• Study type: Interventional
• Enrollment: 255 (actual)
• Sponsor: University of North Carolina, Chapel Hill · Academic / Other
• Sex: All
• Age: 18 Years – 39 Years
• Healthy volunteers: Not accepted

Summary

The purpose of this micro-randomized trial is to evaluate the effects of 7 types of intervention messages targeting specific behavior change techniques (i.e., BCT messages) delivered in "just-in-time" (JIT) moments on daily achievement of weight-related behavioral goals among n=201 young adults with overweight and obesity, participating in a digital, mobile comprehensive lifestyle intervention. "Just-in-time adaptive interventions" (JITAIs) are an alternative to the "one size fits all" approach of mobile intervention development that can provide tailored, real-time messaging and support for young adults.

Detailed description

An estimated 1 in 2 US adults will have obesity by 2030, which is a major cause of morbidity and mortality. The highest risk of weight gain is among young adults ages 18-35 years. In-person behavioral interventions generally produce clinically significant weight losses, but cost and reduced reach limit their ability to impact obesity at a population level. Web-based interventions that mimic the structure of weekly face-to-face treatment have proven a viable alternative, though weight losses are generally smaller than in-person treatment. Mobile treatments have the potential for high reach, but have been less effective, producing 1-3 kgs over 6 months. Newer digital intervention approaches called "just-in-time adaptive interventions" (JITAIs) promise to improve upon mobile outcomes by offering adaptive, personalized feedback on behavior, which consists of providing the "right type of support" at "the right time" rather than on a fixed schedule. This "just-in- time," or JIT, approach is made possible by the emergence of low-cost and widely available digital health tools that allow for the collection of continually updated health data. However, to date, no JITAIs have successfully targeted multiple weight-related behaviors (weighing, activity, and diet), and there has been no systematic examination of what types of messaging interventions best promote adherence to these three weight loss behaviors, for whom they are effective, and under what conditions. To address this problem, a micro-randomized trial will be used to evaluate the effects of 7 types of intervention messages targeting specific behavior change techniques (i.e., BCT messages) delivered in JIT moments on daily achievement of behavioral goals among n=201 young adults with overweight and obesity. All participants will receive a 6-month behavioral weight loss intervention using our Nudge mobile app, which includes evidence-based weekly lessons, tailored feedback, self-monitoring, and daily BCT messages. Participants will receive a wireless scale, activity tracker, and track "red" foods (high-calorie foods) in the app and have 3 goals: weigh daily, a daily active minutes goal that gradually increases if met, and a daily red foods limit. At 3 decision points per day, participants will be micro-randomized to receive or not receive 1 of 7 types of BCT messages. Each intervention message has unique decision rules for availability. Candidate intervention message options have been carefully selected from empirical evidence, tested in our prior studies, or are from our pilot micro-randomized trial. Assessments will occur daily, and at 0, 3 and 6 months, to accomplish the following specific aims: 1) Evaluate the effects of each behavior change technique message (i.e., BCT message) on daily adherence to weight loss behaviors; 2) Determine whether the effects of BCT messages on proximal outcomes change over time; and 3) Assess whether the effects of BCT messages on proximal outcomes are moderated by participants' contextual factors. Findings will guide how adaptive, behaviorally- and contextually-dependent messages are incorporated into future JITAIs for weight loss.

Conditions

• Obesity
• Overweight
• Overweight and Obesity

Interventions

Type	Name	Description
BEHAVIORAL	Core Behavioral Weight Loss (BWL) Intervention	All participants receive a mobile behavioral weight loss intervention delivered through a study smartphone app with weekly behavioral lessons, food tracking log, weekly tailored feedback, and daily weight-related behavioral goals; a connected physical activity tracker and wireless scale. As micro-randomized trials are sequential, full factorial experiments, this core intervention component is combined with each of the 7 intervention messages (i.e., Behavior Change Technique (BCT) messages) to be tested repeatedly over time. Participants will be evaluated at each of 3 decision points (morning, midday, evening) on each day of the study, and if eligible then micro-randomized, to receive or not receive, 1 of 7 types of daily intervention messages promoting achievement of proximal weight-related behavioral goals.
BEHAVIORAL	Behavior Change Technique 1 Message (Action Planning)	Core BWL Intervention + Message in smartphone app prompts detailed planning of performance of one of the 3 target behaviors (daily weighing, active minutes, red food intake).
BEHAVIORAL	Behavior Change Technique 2 Message (Discrepancy between Current Behavior and Goal)	Core BWL Intervention + Message in smartphone app provides feedback on each of the 3 target behaviors (daily weighing, active minutes, red food intake) in the form of information drawing attention to discrepancies between participants' current behavior and participants' daily goals.
BEHAVIORAL	Behavior Change Technique 3 Message (Feedback on Outcome of Behavior)	Core BWL Intervention + Message in smartphone app provides participants with feedback on their weight change, relating it to their performance on one of the 3 target behaviors (daily weighing, active minutes, red food intake).
BEHAVIORAL	Behavior Change Technique 4 Message (Social Support)	Core BWL Intervention + Message in smartphone app advises participants on eliciting the provision of social support from their existing network related to one of the 3 target behaviors (daily weighing, active minutes, red food intake).
BEHAVIORAL	Behavior Change Technique 5 Message (Social Comparison)	Core BWL Intervention + Message in smartphone app systematically induces comparison of participants' behavioral performance with other participants, including general, upward (i.e., comparison to participants doing better: weighing more, engaging in more activity, staying within red food limits), and downward comparisons (to participants doing worse).
BEHAVIORAL	Behavior Change Technique 6 Message (Social Reward)	Core BWL Intervention + Message in smartphone app reinforces participants' effort or progress in performing one of the 3 target behaviors (daily weighing, active minutes, red food intake).
BEHAVIORAL	Behavior Change Technique 7 Message (Focus on Past Success)	Core BWL Intervention + Message in smartphone app advises participants to think about or list previous successes related to performing one of the 3 target behaviors (daily weighing, active minutes, red food intake).

Timeline

• Start date: 2023-08-25
• Primary completion: 2025-01-05
• Completion: 2025-01-27
• First posted: 2022-11-22
• Last updated: 2026-02-17
• Results posted: 2026-01-27

Locations

1 site across 1 country: United States