Mobile obesity interventions have the potential to reach a diverse population in need; however, while effective, have not resulted in weight losses obtained in in-person interventions. Newer digital approaches called Just-in-Time Adaptive Interventions (JITAI) that offer adaptive, personalized feedback 'when needed' and in 'real time' offer an opportunity to use digital health tools "just in time". This study seeks to identify the optimal components of a comprehensive weight loss JITAI that results in weight losses that meet or exceed those in existing remotely delivered interventions.
Obesity has reached epidemic proportions in the United States and is recognized as a major cause of morbidity and mortality. Young adults (18-35 years) are at particularly high risk for weight gain and obesity. In-person behavioral interventions generally produce clinically significant weight losses; however, cost and access limit their potential to reduce obesity at a population level. Although web-based interventions that mimic the structure of weekly face-to-face treatment have proven a viable alternative treatment, weight losses are generally smaller than in-person treatment. Exclusively mobile treatments 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 outcomes by offering adaptive, personalized feedback on behavior "when needed" in "real 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, few studies have used JIT approaches in remotely delivered, fully scalable weight loss interventions. Although JITAIs are a potentially transformative approach to delivering obesity interventions, a major obstacle in their development is efficient selection of components and systematic design of an optimized intervention package that produces clinically meaningful weight losses with a population-level strategy. To solve this problem, this trial will use the Multiphase Optimization Strategy (MOST), an engineering-inspired framework, and a highly efficient experimental design to identify which levels of 5 intervention components contribute meaningfully to change in weight over 6 months among young adults with overweight and obesity. All participants (n=608) will receive a core 6-month weight loss intervention that includes evidence-based lessons, behavioral skills training, and daily weighing. With the goal of determining if greater adaptation will lead to greater weight loss, participants will be randomized to standard versus more adaptive options of 5 additional intervention components: 1) diet monitoring approach (standard vs. simplified), 2) adaptive physical activity goals (weekly vs. daily), 3) decision points for message timing (fixed vs. adaptive), 4) decision rules for message content (standard vs. adaptive), and 5) message choice (no vs. yes). Candidate components have been carefully selected from empirical evidence, tested in prior studies conducted by the research team, or in a pilot micro-randomized trial conducted by the research team. Assessments will occur at 0, 3 and 6 months to accomplish the following specific aims: 1) Build an optimized JITAI consisting of the set of intervention components that yield the greatest improvement in weight change among young adults at 6 months; 2) Conduct mediation analyses to test the relationships between the intervention components and hypothesized proximal mediators (self-regulation, competence, relatedness, relevance, autonomy) and more distal behavioral mediators (dietary intake, physical activity, and daily self-weighting); and 3) Conduct exploratory analyses of program engagement.
Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.
Standard monitoring using smartphone tracking of all calorie intake.
Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.
University of North Carolina at Chapel Hill
Chapel Hill, North Carolina, United States
Weight (kg)
Estimated mean weight change in kg from baseline to 6 months for each of the two levels of each component (factor) obtained from intent-to-treat (ITT) linear mixed models of analysis of variance. More negative values of weight change indicate greater weight loss (6-month weight - baseline weight).
Time frame: Baseline, 6 months
Weight (kg)
Estimated mean weight change in kg from baseline to 3 months for each of the two levels of each component (factor) obtained from intent-to-treat (ITT) linear mixed models of analysis of variance. More negative values of weight change indicate greater weight loss (3-month weight - baseline weight).
Time frame: Baseline, 3 months
Percent of Participants Reaching >/= 5% Weight Loss
Percent change in body weight will be calculated (6 month weight - baseline weight/100) and determined to be at or above 5% indicating a clinically significant change.
Time frame: Baseline to 6 months
Diet
Change in daily caloric intake from baseline to 6 months as measured using the self-administered National Cancer Institute's Automated Self- Administered 24-hour Recall (ASA-24), a 24-hour recall that is self-administered on a week day and a weekend day at each timepoint. Change calculated as (daily kcal at 6 months - daily kcal at baseline).
Time frame: Baseline, 6 months
Physical Activity
Change in physical activity from baseline to 3 and 6 months as measured using the Paffenbarger Physical Activity Questionnaire (PPAQ). The PPAQ assesses amount of planned and lifestyle associated physical activity performed during a typical week. The PPAQ consists of three components: (1) stair climbing, (2) walking, and (3) sports and recreation. Participants report the frequency and duration of physical activity in the past week. Scoring yields energy expenditure from physical activity per week (kcal/week). Higher scores translate into greater energy expenditure per week (i.e.,better outcome). Range is 0 - no theoretical maximum. Outcome is change in kcal burned per week.
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Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
759
Physical activity goals that adapt once each day using the participants' data derived from activity tracker.
Physical activity goals that adapt once each week using the participants' data derived from activity tracker.
Message timing is fixed and evaluated at specific times each day to determine message eligibility.
Message timing is adaptive and derived from individual user data to determine message eligibility.
Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.
Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.
Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision
Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.
Time frame: Baseline,3 months, 6 months
Sedentary Behavior Score
Change in sedentary behavior from baseline to 3 and 6 months as measured using the 12- item Sedentary Behavior Questionnaire which asks respondents to indicate the number of hours they spend on a typical weekday and a typical weekend day doing each of six activities. The scale ranges from "none" to "6 or more hours" for each item. Higher values on the Sedentary Behavior Questionnaire indicate greater amount of time spent in sedentary behavior. Range is 0 to 24 hours and outcome is change in minutes per day.
Time frame: Baseline, 3 months, 6 months
Autonomy Support Score
Autonomy support at 3 and 6 months. Items are adapted from the Health Care Climate Questionnaire, which is a measure of how the participant perceives support from a healthcare provider, to measure autonomy support from the program. The scale includes 15 items rated on a scale of 1 (strongly disagree) to 7 (strongly agree) (e.g., "I feel that \[the program\] has provided me choices and options.") Scores are calculated by averaging the individual item scores (with item 13 reverse-scored). Higher average scores represent a higher level of perceived autonomy support. Outcomes are the mean value at 3 months and the mean value at 6 months.
Time frame: 3 months, 6 months
Competence for Diet and Physical Activity Scores
Change in perceived competence from baseline to 3 and 6 months as measured using the The Perceived Competence Scale. The Scale measures perceived competence for diet (4 items) and physical activity (4 items). Items are rated on a 7-point Likert scale (1 = not at all true, 7 = very true), and include items such as "I feel confident in my ability to maintain a healthy diet." Scores are summed for the items in the subscale (diet and physical activity) and the range for each subscale is 4 - 28. Greater values indicate higher levels of perceived competence for engaging in positive diet and physical activity behaviors. Scores are summed for the items in each subscale separately (diet and physical activity). Outcomes are change in perceived competence for diet and change in perceived competence for physical activity.
Time frame: Baseline, 3 months, 6 months
Perceived Message Relevance Score
Perceived message relevance at 3 and 6 months as measured using two items used in our previous work and adapted from previous studies of tailored messages. Participants were asked to rate how strongly they disagree or agree with the statements about messages being "written personally for me" and "applied to my life." Responses are on a 5-point scale from 1 (strongly disagree) to 5 (strongly agree). The values of the two items are averaged for a final score. Higher values indicate that a participant perceives the messages received in the program are more relevant to them.
Time frame: 3 months, 6 months
Treatment Self-Regulation Score
Change in treatment self-regulation from baseline to 3 and 6 months as measured using the Treatment Self-Regulation Questionnaire (TSRQ). The TSRQ assesses autonomous and controlled motivation for making changes in diet (15 items) and physical activity (15 items). Examples item: "Because I feel that I want to take responsibility for my own health" answered on a scale of 1 (not at all true) to 7 (very true)." Calculating the scores for the sub-scales will consist of averaging the items on that subscale. They are: Autonomous Regulation: 2, 3, 7, 10, 13, 16, 18, 19 Controlled Regulation: 1, 4, 5, 6, 8, 9, 11, 12, 14, 15, 17. Responses to the items within the subscale are averaged with the range of scores being 1 to 7. Higher values on each subscale indicate greater levels of that type of motivation. Outcomes are changes in autonomous and controlled motivation for diet at 3 and 6 months, and changes in autonomous and controlled motivation for activity at 3 and 6 months.
Time frame: Baseline, 3 months, 6 months
Relatedness Score
Relatedness at 3 and 6 months as measured with 3 items adapted from the 8-item Relatedness subscale of the Basic Need Satisfaction at Work Scale. Examples include "The messages demonstrate caring about me as a person" and are scored on a Likert scale from 1 (strongly disagree) to 7 (strongly agree). Responses are averaged with a range of 1 to 7. Higher scores indicate a higher level of perceived relatedness from the intervention messages.
Time frame: 3 months, 6 months
Diet Self-monitoring Adherence
Mean number of days of complete dietary tracking summed over the 6-month study period.
Time frame: Baseline to 6 months (daily)
Weighing Adherence
Mean number of days of self-weighing over the 6 month period.
Time frame: Baseline to 6 months (daily)
Physical Activity Self-monitoring Adherence
Mean number of days of physical activity tracking over the 6 month period as measured by Fitbit tracker wear.
Time frame: Baseline to 6 months (daily)