ObesityNudgeNCT05625061
Just-in-time Adaptive Intervention Messaging in a Digital Weight Loss Intervention for Young Adults
A study testing Core Behavioral Weight Loss (BWL) Intervention, Behavior Change Technique 1 Message (Action Planning) and Behavior Change Technique 2 Message (Discrepancy between Current Behavior and Goal) in people with Obesity and Overweight, run by University of North Carolina, Chapel Hill at 1 site in United States.
Trial 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… Read more about this study
- Who is it for?
- Ages 18 to 39 years
- Conditions the study is for
- Obesity, Overweight, Overweight and Obesity
- What is being tested?
- Core Behavioral Weight Loss (BWL) Intervention, Behavior Change Technique 1 Message (Action Planning) and Behavior Change Technique 2 Message (Discrepancy between Current Behavior and Goal)
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 255 participants
- Where
- 1 siteUnited States
- Study dates
- 25 Aug 2023to 27 Jan 2025
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 39 years
- All sexes
- No healthy volunteers
- Adult
Who may be able to join
- Body mass index (BMI) of 25 - 45 kg/m^2 at baseline
- English-speaking, reading, and writing
- Own a smartphone with a data and text messaging plan
Who cannot join
- Type 1 diabetes or currently receiving medical treatment for Type 2 diabetes
- Report a heart condition, chest pain during periods of activity or rest, or loss of consciousness on the Physical Activity Readiness Questionnaire (PAR-Q; items 1-4).
- Other health problems which may influence the ability to walk for physical activity or be associated with unintentional weight change, including cancer treatment within the past 5 years or tuberculosis
- Lost 10 lbs. or more of body weight (and kept it off) in the last 6 months
- Past diagnosis of or receiving treatment for a clinically diagnosed eating disorder (anorexia nervosa or bulimia nervosa)
- Current symptoms of alcohol or substance dependence
Show all 17Show fewer
- Currently pregnant, pregnant within the past 6 months, or planning to become pregnant within the next 6 months
- Untreated thyroid disease or any changes (type or dose) in thyroid medication in last 6 months
- Hospitalization for depression or other psychiatric disorder within the past 12 months
- History of psychotic disorder or bipolar disorder
- Currently participating in a weight loss, nutrition, or physical activity study or program or other study that would interfere with this study
- Currently using prescription medications with known effects on appetite or weight (e.g., oral steroids, weight loss medications), with the exception of individuals on a stable dose of Selective Serotonin Reuptake Inhibitors (SSRIs) for 3 months)
- Previous surgical procedure for weight loss or planned weight loss surgery in the next year
- Another member of the household is a participant or staff member on this trial
- Reason to suspect that the participant would not adhere to the study intervention
- Reside outside of the United States
- Have participated in another study conducted by the UNC Weight Research Program within the past 12 months
Trial locations and contacts
1 site in 1 country.
United States1 site
University of North Carolina at Chapel Hill
Chapel Hill, North Carolina, 27514
About this study
Official title: A Micro-randomized Trial of JITAI Messaging to Improve Adherence to Multiple Weight Loss Behaviors in Young Adults
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.
Read the 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
- Being tested
- Core Behavioral Weight Loss (BWL) Intervention, Behavior Change Technique 1 Message (Action Planning), Behavior Change Technique 2 Message (Discrepancy between Current Behavior and Goal), Behavior Change Technique 3 Message (Feedback on Outcome of Behavior), Behavior Change Technique 4 Message (Social Support)
- Keywords
- Mobile intervention, Diet, Physical Activity, Behavioral weight loss
- Medical subject headings
- Obesity, Overweight, Motor Activity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Core Behavioral Weight Loss (BWL) InterventionBehavioural
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.
Behavior Change Technique 1 Message (Action Planning)Behavioural
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).
Behavior Change Technique 2 Message (Discrepancy between Current Behavior and Goal)Behavioural
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.
Behavior Change Technique 3 Message (Feedback on Outcome of Behavior)Behavioural
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).
Behavior Change Technique 4 Message (Social Support)Behavioural
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).
Behavior Change Technique 5 Message (Social Comparison)Behavioural
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).
Behavior Change Technique 6 Message (Social Reward)Behavioural
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).
Behavior Change Technique 7 Message (Focus on Past Success)Behavioural
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).
| Study group | Role | What they receive |
|---|---|---|
| Core Behavioral Weight Loss (BWL) Intervention | Experimental | Behavioral weight loss core intervention, includes activity tracker, wireless scale, daily self-weighing, and smartphone app with weekly behavioral lessons, food tracking log, weekly tailored feedback summary, and daily weight-related behavioral goals. Core intervention component is combined with each of the 7 intervention messages to be tested repeatedly over time. Receives: Behavioral: Core Behavioral Weight Loss (BWL) Intervention |
| Core BWL Intervention + BCT 1 Message (Action Planning) | Experimental | Core BWL Intervention + Message testing the Behavior Change Technique "Action Planning" Receives: Behavioral: Behavior Change Technique 1 Message (Action Planning) |
| Core BWL Intervention + BCT 2 Message (Discrepancy) | Experimental | Core BWL Intervention + Message testing the Behavior Change Technique "Discrepancy Between Current Behavior and Goal" Receives: Behavioral: Behavior Change Technique 2 Message (Discrepancy between Current Behavior and Goal) |
| Core BWL Intervention + BCT 3 Message (Feedback on Outcome of Behavior) | Experimental | Core BWL Intervention + Message testing the Behavior Change Technique "Feedback on Outcome of Behavior" Receives: Behavioral: Behavior Change Technique 3 Message (Feedback on Outcome of Behavior) |
| Core BWL Intervention + BCT 4 Message (Social Support) | Experimental | Core BWL Intervention + Message testing the Behavior Change Technique "Social Support" Receives: Behavioral: Behavior Change Technique 4 Message (Social Support) |
| Core BWL Intervention + BCT 5 Message (Social Comparison) | Experimental | Core BWL Intervention + Message testing the Behavior Change Technique "Social Comparison" Receives: Behavioral: Behavior Change Technique 5 Message (Social Comparison) |
| Core BWL Intervention + BCT 6 Message (Social Reward) | Experimental | Core BWL Intervention + Message testing the Behavior Change Technique "Social Reward" Receives: Behavioral: Behavior Change Technique 6 Message (Social Reward) |
| Core BWL Intervention + BCT 7 Message (Focus on Past Success) | Experimental | Core BWL Intervention + Message testing the Behavior Change Technique "Focus on Past Success" Receives: Behavioral: Behavior Change Technique 7 Message (Focus on Past Success) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Met Daily Weighing Goal
Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit. Among the randomization observations in which the participant had not yet weighed, this outcome is the number of observations in which the daily weighing goal was met after receiving or not receiving a message and before the end of the day. Observations are accumulated across participants and across time. On the day of randomization, a dichotomous outcome of whether a participant weighed or did not weigh is calculated.
Measured: Daily throughout the study, a total of up to 24 weeks
Met Daily Active Minutes Goal
Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit. Among the randomization observations in which the participant had not yet met their active minutes goal, this outcome is the number of observations in which the daily active minutes goal was met after receiving or not receiving a message and before the end of the day. Observations are accumulated across participants and across time. On the day of randomization, a dichotomous outcome of whether a participant met or did not meet their active minutes goal is calculated.
Measured: Daily throughout the study, a total of up to 24 weeks
At or Under Daily Red Foods Limit
Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit. Among the randomization observations in which the participant had not yet exceeded their red foods limit, this outcome is the number of observations in which the participant stayed at or under their daily red foods limit after receiving or not receiving a message and before the end of the day. Observations are accumulated across participants and across time. On the day of randomization, a dichotomous outcome of whether a participant stayed at or under their red foods limit or did not is calculated.
Measured: Daily throughout the study, a total of up to 24 weeks
Secondary outcomes (10)
Weight Change
Absolute weight change (kg) from baseline to 6 months (6-month weight - baseline weight). Weight was objectively measured on a digital scale in the participant's home.
Measured: Baseline, 6 months
Percent Weight Change
Change in weight (%) from baseline to 6 months. Weight will be objectively measured on a digital scale in the participant's home. Percent weight change at 6 months is calculated as ((weight (kg) at 6 months - weight (kg) at baseline)/(weight (kg) at baseline))*100
Measured: Baseline, 6 months
Proportion of Days Met Daily Weighing Goal
Calculation of the proportion of study days weighed across all study participants across all days.
Measured: Daily throughout the study, a total of up to 24 weeks
Proportion of Daily Active Minutes Goal Met
Among randomization observations, the mean proportion of the daily active minutes goal that was achieved that day. Observations are accumulated across participants and across time. Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit. On the day of randomization, a ratio of the participant's total active minutes that day over their daily active minutes goal is calculated (total active minutes that day/daily active minutes goal), such that observations in which a participant exceeded their goal have a proportion over 1.0 and those in which a participant did not reach their active minutes goal have a proportion under 1.0.
Measured: Daily throughout the study, a total of up to 24 weeks
Proportion of Daily Red Foods Limit
Among randomization observations, the mean proportion of the daily red foods limit that was tracked that day. Observations are accumulated across participants and across time. Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit. On the day of randomization, a ratio (proportion) of the participant's total red foods that day over their daily red foods limit is calculated (total red foods that day/daily red foods limit), such that observations in which a participant exceeded their limit have a proportion over 1.0 and those in which a participant did not exceed their red foods limit have a proportion under 1.0.
Measured: Daily throughout the study, a total of up to 24 weeks
Number of Active Minutes
Among randomization observations, the total number of active minutes that was achieved by the participant on the day of randomization. Observations are accumulated across participants and across time. Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit.
Measured: Daily throughout the study, a total of up to 24 weeks
Number of Red Foods
Among randomization observations, the total number of red foods that was tracked by the participant on the day of randomization. Observations are accumulated across participants and across time. Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit.
Measured: Daily throughout the study, a total of up to 24 weeks
Met Daily Weighing Goal Tomorrow
Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit. Among the randomization observations, this outcome is the number of observations in which the daily weighing goal was met the day following randomization. Observations are accumulated across participants and across time. On the day following randomization, a dichotomous outcome of whether a participant weighed or did not weigh is assessed.
Measured: Daily throughout the study, a total of up to 24 weeks
Met Daily Active Minutes Goal Tomorrow
Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit. Among the randomization observations, this outcome is the number of observations in which the daily active minutes goal was met the day following randomization. Observations are accumulated across participants and across time. On the day following randomization, a dichotomous outcome of whether a participant met or did not meet their active minutes goal is calculated.
Measured: Daily throughout the study, a total of up to 24 weeks
At or Under Daily Red Foods Limit Tomorrow
Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit. Among the randomization observations, this outcome is the number of observations in which the participant stayed at or under the daily red foods limit the day following randomization. Observations are accumulated across participants and across time. On the day following randomization, a dichotomous outcome of whether a participant stayed at or under the daily red foods limit is calculated.
Measured: Daily throughout the study, a total of up to 24 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Nov 2022
- Study start25 Aug 2023
- Primary completion5 Jan 2025
- Study completion27 Jan 2025
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (1)Papers the sponsor has linked to this study.
- Other trials for ObesityStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Sequential
- Model description
- This is a micro-randomized trial, a form of a sequential, factorial trial. At every time point, a participant is micro-randomized to receive or not receive an intervention message.
- Masking
- Double blind
- Who is masked
- Investigator, Outcomes assessor
- Enrolment
- 255 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of North Carolina, Chapel Hill
- Sponsor type
- University, hospital or other
- Collaborators
- National Heart, Lung, and Blood Institute (NHLBI)
- Responsible party
- Sponsor
- Investigators
- Carmina G. Valle, PhD, MPH, Principal investigator, Assistant Professor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05625061
- Sponsor's protocol ID
- 22-0170
- Other IDs
- 1R01HL161373
- Acronym
- Nudge
- Status last verified
- Jan 2025
- First submitted
- 14 Nov 2022
- Last updated
- 17 Feb 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Deidentified individual data that supports the results will be shared beginning 12 to 36 months following publication provided the investigator who proposes to use the data has submitted a written proposal to the Principal Investigator describing the intended use of the data and approval from an Institutional Review Board (IRB), Independent Ethics Committee (IEC), or Research Ethics Board (REB), as applicable, and executes a data use/sharing agreement with UNC. The release of specific data may be delayed if data are part of an analysis being prepared for a separate publication.
Publications
Valle CG, Nezami BT, Hatley KE, Diamond MA, Polzien K, Wasser HM, O'Shea NG, Tate DF. Promoting adherence to weight-related behaviors in young adults: Design of the Nudge microrandomized trial. Contemp Clin Trials. 2026 Jun;165:108318. doi: 10.1016/j.cct.2026.108318. Epub 2026 Apr 15.
PubMed 41997542
Study at a glance
From the registry record, last updated by the sponsor on 17 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Micro-randomized Trial of JITAI Messaging to Improve Adherence to Multiple Weight Loss Behaviors in Young Adults
- ClinicalTrials.gov ID
- NCT05625061
- Acronym / sponsor ID
- Nudge / 22-0170
- Conditions
- Obesity, Overweight, Overweight and Obesity
- Keywords
- Mobile intervention, Diet, Physical Activity, Behavioral weight loss
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 255 participants (actual)
- Lead sponsor
- University of North Carolina, Chapel HillUniversity, hospital or other
- Collaborators
- National Heart, Lung, and Blood Institute (NHLBI)
- Study start
- 25 Aug 2023 (actual)
- Primary completion
- 5 Jan 2025 (actual)
- Study completion
- 27 Jan 2025 (actual)
- First posted
- 22 Nov 2022 (actual)
- Results
- Posted 27 Jan 2026
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Sequential
- Masking
- Double blind (investigator, outcomes assessor)
- Number of arms
- 8
- Model description
- This is a micro-randomized trial, a form of a sequential, factorial trial. At every time point, a participant is micro-randomized to receive or not receive an intervention message.
| Arm | Type | Receives |
|---|---|---|
| Core Behavioral Weight Loss (BWL) Intervention | Experimental | Behavioral: Core Behavioral Weight Loss (BWL) InterventionBehavioral weight loss core intervention, includes activity tracker, wireless scale, daily self-weighing, and smartphone app with weekly behavioral lessons, food tracking log, weekly tailored feedback summary, and daily weight-related behavioral goals. Core intervention component is combined with each of the 7 intervention messages to be tested repeatedly over time. |
| Core BWL Intervention + BCT 1 Message (Action Planning) | Experimental | Behavioral: Behavior Change Technique 1 Message (Action Planning)Core BWL Intervention + Message testing the Behavior Change Technique "Action Planning" |
| Core BWL Intervention + BCT 2 Message (Discrepancy) | Experimental | Behavioral: Behavior Change Technique 2 Message (Discrepancy between Current Behavior and Goal)Core BWL Intervention + Message testing the Behavior Change Technique "Discrepancy Between Current Behavior and Goal" |
| Core BWL Intervention + BCT 3 Message (Feedback on Outcome of Behavior) | Experimental | Behavioral: Behavior Change Technique 3 Message (Feedback on Outcome of Behavior)Core BWL Intervention + Message testing the Behavior Change Technique "Feedback on Outcome of Behavior" |
| Core BWL Intervention + BCT 4 Message (Social Support) | Experimental | Behavioral: Behavior Change Technique 4 Message (Social Support)Core BWL Intervention + Message testing the Behavior Change Technique "Social Support" |
| Core BWL Intervention + BCT 5 Message (Social Comparison) | Experimental | Behavioral: Behavior Change Technique 5 Message (Social Comparison)Core BWL Intervention + Message testing the Behavior Change Technique "Social Comparison" |
| Core BWL Intervention + BCT 6 Message (Social Reward) | Experimental | Behavioral: Behavior Change Technique 6 Message (Social Reward)Core BWL Intervention + Message testing the Behavior Change Technique "Social Reward" |
| Core BWL Intervention + BCT 7 Message (Focus on Past Success) | Experimental | Behavioral: Behavior Change Technique 7 Message (Focus on Past Success)Core BWL Intervention + Message testing the Behavior Change Technique "Focus on Past Success" |
Who may qualify
- Ages
- 18 to 39 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (3 listed)
- Body mass index (BMI) of 25 - 45 kg/m^2 at baseline
- English-speaking, reading, and writing
- Own a smartphone with a data and text messaging plan
Key exclusion criteria (17 listed)
- Type 1 diabetes or currently receiving medical treatment for Type 2 diabetes
- Report a heart condition, chest pain during periods of activity or rest, or loss of consciousness on the Physical Activity Readiness Questionnaire (PAR-Q; items 1-4).
- Other health problems which may influence the ability to walk for physical activity or be associated with unintentional weight change, including cancer treatment within the past 5 years or tuberculosis
- Lost 10 lbs. or more of body weight (and kept it off) in the last 6 months
- Past diagnosis of or receiving treatment for a clinically diagnosed eating disorder (anorexia nervosa or bulimia nervosa)
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Core Behavioral Weight Loss (BWL) InterventionAll 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. | Behavioural | Core Behavioral Weight Loss (BWL) Intervention |
| 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). | Behavioural | Core BWL Intervention + BCT 1 Message (Action Planning) |
| 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. | Behavioural | Core BWL Intervention + BCT 2 Message (Discrepancy) |
| 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). | Behavioural | Core BWL Intervention + BCT 3 Message (Feedback on Outcome of Behavior) |
| 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). | Behavioural | Core BWL Intervention + BCT 4 Message (Social Support) |
| 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). | Behavioural | Core BWL Intervention + BCT 5 Message (Social Comparison) |
| 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). | Behavioural | Core BWL Intervention + BCT 6 Message (Social Reward) |
| 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). | Behavioural | Core BWL Intervention + BCT 7 Message (Focus on Past Success) |
Primary outcome
Met Daily Weighing Goal
Time frame: Daily throughout the study, a total of up to 24 weeks
Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit. Among the randomization observations in which the participant had not yet weighed, this outcome is the number of observations in which the daily weighing goal was met after receiving or not receiving a message and before the end of the day. Observations are accumulated across participants and across time. On the day of randomization, a dichotomous outcome of whether a participant weighed or did not weigh is calculated.
Met Daily Active Minutes Goal
Time frame: Daily throughout the study, a total of up to 24 weeks
Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit. Among the randomization observations in which the participant had not yet met their active minutes goal, this outcome is the number of observations in which the daily active minutes goal was met after receiving or not receiving a message and before the end of the day. Observations are accumulated across participants and across time. On the day of randomization, a dichotomous outcome of whether a participant met or did not meet their active minutes goal is calculated.
At or Under Daily Red Foods Limit
Time frame: Daily throughout the study, a total of up to 24 weeks
Each observation corresponds to a microrandomization decision point; the reported value reflects the outcome measured within that unit. Among the randomization observations in which the participant had not yet exceeded their red foods limit, this outcome is the number of observations in which the participant stayed at or under their daily red foods limit after receiving or not receiving a message and before the end of the day. Observations are accumulated across participants and across time. On the day of randomization, a dichotomous outcome of whether a participant stayed at or under their red foods limit or did not is calculated.
10 secondary outcomes
Weight Change
Time frame: Baseline, 6 months
Percent Weight Change
Time frame: Baseline, 6 months
Proportion of Days Met Daily Weighing Goal
Time frame: Daily throughout the study, a total of up to 24 weeks
Proportion of Daily Active Minutes Goal Met
Time frame: Daily throughout the study, a total of up to 24 weeks
Proportion of Daily Red Foods Limit
Time frame: Daily throughout the study, a total of up to 24 weeks
Number of Active Minutes
Time frame: Daily throughout the study, a total of up to 24 weeks
Number of Red Foods
Time frame: Daily throughout the study, a total of up to 24 weeks
Met Daily Weighing Goal Tomorrow
Time frame: Daily throughout the study, a total of up to 24 weeks
Met Daily Active Minutes Goal Tomorrow
Time frame: Daily throughout the study, a total of up to 24 weeks
At or Under Daily Red Foods Limit Tomorrow
Time frame: Daily throughout the study, a total of up to 24 weeks
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 17 Feb 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Derived from this study: PubMed 41997542Valle CG, Nezami BT, Hatley KE, Diamond MA, Polzien K, Wasser HM, O'Shea NG, Tate DF. Promoting adherence to weight-related behaviors in young adults: Design of the Nudge microrandomized trial. Contemp Clin Trials. 2026 Jun;165:108318. doi: 10.1016/j.cct.2026.108318. Epub 2026 Apr 15.
- Individual participant dataSharing planned: Yes. Deidentified individual data that supports the results will be shared beginning 12 to 36 months following publication provided the investigator who proposes to use the data has submitted a written proposal to the Principal Investigator describing the intended use of the data and approval from an Institutional Review Board (IRB), Independent Ethics Committee (IEC), or Research Ethics Board (REB), as applicable, and executes a data use/sharing agreement with UNC. The release of specific data may be delayed if data are part of an analysis being prepared for a separate publication.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Carmina G. Valle, PhD, MPH principal investigator
Assistant Professor
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Core Behavioral Weight Loss (BWL) Intervention, Behavior Change Technique 1 Message (Action Planning) and Behavior Change Technique 2 Message (Discrepancy between Current Behavior and Goal) in people with Obesity and Overweight, run by University of North Carolina, Chapel Hill at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 3 inclusion and 17 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 17 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Yes. Results are posted in the registry (first posted 27 Jan 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Met Daily Weighing Goal (time frame: Daily throughout the study, a total of up to 24 weeks). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT05625061, which also lists 1 linked publication.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 17 Feb 2026.