Adaptive Goals and Interventions for Lifestyle Enhancement

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

Official Title
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Optimization of a mHealth Behavioral Weight Loss Intervention for Young Adults

Conditions
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Obesity

Intervention / Treatment
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* Behavioral: Core
* Behavioral: Standard Diet Monitoring
* Behavioral: Simplified Diet Monitoring
* Behavioral: Adaptive Activity Goals (Daily)
* Behavioral: Adaptive Activity Goals (Weekly)
* Behavioral: Message Decision Points (Fixed)
* Behavioral: Message Decision Points (Adaptive)
* Behavioral: Message Decision Rules (Standard)
* Behavioral: Message Decision Rules (Adaptive)
* Behavioral: Message Choice (No)
* Behavioral: Message Choice (Yes)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: body mass index (BMI) of 25-45 kg/m^2 English-speaking and writing own a smartphone with a data and text messaging plan reporting engaging in less than 210 minutes/week of moderate-to-vigorous intensity activity willing to be randomized to any levels of the factors Exclusion Criteria: Type 1 diabetes or currently receiving medical treatment for Type 2 diabetes 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 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) Lost 10 or more pounds (and kept it off) in the last 6 months Currently taking weight loss medications Report a past diagnosis of or current treatment for a DSM-V (Diagnostic and Statistical Manual 5) eating disorder (anorexia nervosa or bulimia nervosa) Currently pregnant, pregnant within the past 6 months, or planning to become pregnant within the next 6 months Hospitalization for depression or other psychiatric disorder within the past 12 months History of psychotic disorder or bipolar disorder Another member of the household is a participant or staff member on this trial Currently participating in a weight loss, nutrition or physical activity study or program or other study that would interfere with this study

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Factorial Assignment
Interventional Model Description: This study uses a full factorial experimental design testing the efficacy of five intervention components, each with two levels
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Condition 1<br>Core + Standard Diet Monitoring + Daily Activity Goal + Fixed Timing + Standard Content + No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 2<br>Core + Standard Diet Monitoring + Daily Activity Goal + Fixed Timing + Standard Content + Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 3<br>Core + Standard Diet Monitoring + Daily Activity Goal + Fixed Timing + Adaptive Content + No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 4<br>Core + Standard Diet Monitoring + Daily Activity Goal + Fixed Timing + Adaptive Content + Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 5<br>Core+Standard Diet Monitoring+Daily Activity Goal+Adaptive Timing+Standard Content+No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 6<br>Core + Standard Diet Monitoring + Daily Activity Goal + Adaptive Timing + Standard Content + Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 7<br>Core+ Standard Diet Monitoring+ Daily Activity Goal+ Adaptive Timing+ Adaptive Content+ No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 8<br>Core + Standard Diet Monitoring + Daily Activity Goal + Adaptive Timing + Adaptive Content + Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 9<br>Core + Standard Diet Monitoring + Weekly Activity Goal + Fixed Timing + Standard Content + No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 10<br>Core + Standard Diet Monitoring + Weekly Activity Goal + Fixed Timing + Standard Content + Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 11<br>Core + Standard Diet Monitoring + Weekly Activity Goal + Fixed Timing + Adaptive Content + No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 12<br>Core + Standard Diet Monitoring + Weekly Activity Goal + Fixed Timing + Adaptive Content + Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 13<br>Core+Standard Diet Monitoring+Weekly Activity Goal+Adaptive Timing+Standard Content+No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 14<br>Core + Standard Diet Monitoring + Weekly Activity Goal + Adaptive Timing + Standard Content + Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 15<br>Core + Standard Diet Monitoring+ Weekly Activity Goal+ Adaptive Timing+ Adaptive Content+ No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 16<br>Core + Standard Diet Monitoring + Weekly Activity Goal + Adaptive Timing + Adaptive Content + Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Standard Diet Monitoring<br>* Standard monitoring using smartphone tracking of all calorie intake.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 17<br>Core+ Simplified Diet Monitoring+ Daily Activity Goal+ Fixed Timing+ Standard Content+ No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 18<br>Core+ Simplified Diet Monitoring+ Daily Activity Goal+ Fixed Timing+ Standard Content+ Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 19<br>Core+ Simplified Diet Monitoring+ Daily Activity Goal+ Fixed Timing+ Adaptive Content+ No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 20<br>Core + Simplified Diet Monitoring + Daily Activity Goal + Fixed Timing + Adaptive Content + Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 21<br>Core+ Simplified Diet Monitoring+ Daily Activity Goal+ Adaptive Timing+ Standard Content+ No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 22<br>Core+ Simplified Diet Monitoring+ Daily Activity Goal+ Adaptive Timing+ Standard Content+ Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 23<br>Core+ Simplified Diet Monitoring+ Daily Activity Goal+ Adaptive Timing+ Adaptive Content+ No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 24<br>Core+ Simplified Diet Monitoring+ Daily Activity Goal+ Adaptive Timing+ Adaptive Content+ Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Daily)<br>* Physical activity goals that adapt once each day using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 25<br>Core+ Simplified Diet Monitoring+ Weekly Activity Goal+ Fixed Timing+ Standard Content+ No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 26<br>Core + Simplified Diet Monitoring + Weekly Activity Goal + Fixed Timing + Standard Content + Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 27<br>Core+ Simplified Diet Monitoring+ Weekly Activity Goal+ Fixed Timing+ Adaptive Content+ No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 28<br>Core + Simplified Diet Monitoring + Weekly Activity Goal + Fixed Timing + Adaptive Content + Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Fixed)<br>* Message timing is fixed and evaluated at specific times each day to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 29<br>Core+ Simplified Diet Monitoring+ Weekly Activity Goal+ Adaptive Timing+ Standard Content+ No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 30<br>Core+ Simplified Diet Monitoring+ Weekly Activity Goal+ Adaptive Timing+ Standard Content+ Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Standard)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|
| Experimental: Condition 31<br>Core+ Simplified Diet Monitoring+ Weekly Activity Goal+ Adaptive Timing+ Adaptive Content+ No Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (No)<br>* Participant choice does not drive adaptation of 1) message type delivered or 2) lapse support provision<br>|
| Experimental: Condition 32<br>Core + Simplified Diet Monitoring + Weekly Activity Goal + Adaptive Timing + Adaptive Content+Choice | Behavioral: Core<br>* Behavioral weight loss core includes behavioral lessons, activity tracker, daily self-weighing, weekly tailored feedback summary.<br>Behavioral: Simplified Diet Monitoring<br>* Simplified diet monitoring using smartphone tracking of red foods using a traffic light approach.<br>Behavioral: Adaptive Activity Goals (Weekly)<br>* Physical activity goals that adapt once each week using the participants' data derived from activity tracker.<br>Behavioral: Message Decision Points (Adaptive)<br>* Message timing is adaptive and derived from individual user data to determine message eligibility.<br>Behavioral: Message Decision Rules (Adaptive)<br>* Decision rules to determine eligibility to receive just-in-time messages consider participant's recent behaviors and overall progress.<br>Behavioral: Message Choice (Yes)<br>* Participant choice drives adaptation of 1) message type delivered and 2) lapse support provision.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Weight | Absolute weight change from baseline to 6 months. Weight will be objectively measured on a digital scale in the participant's home. | Baseline, 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Weight | Absolute weight change from baseline to 3 months. Weight will be objectively measured on a digital scale in the participant's home. | Baseline, 3 months | 
| Achievement of 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. | Baseline to 6 months | 
| Diet | Change in daily caloric intake from baseline to 3 and 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. | 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/kg/week). Higher scores translate into greater energy expenditure per week (i.e.,better outcome). Range is 0 - no theoretical maximum. | 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. | Baseline, 3 months, 6 months | 
| Autonomy Support score | Change in autonomy support from baseline to 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. | Baseline, 3 months, 6 months | 
| Competence for Diet and Physical Activity score | Change in perceived competence from baseline to 3 and 6 months as measured using the The Perceived Competence for 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 the subscale (diet and physical activity) | Baseline, 3 months, 6 months | 
| Perceived Message Relevance score | Change in perceived message relevance from baseline to 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). Higher values indicate that a participant perceives the messages received in the program are more relevant to them. | Baseline, 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. | Baseline, 3 months, 6 months | 
| Relatedness score | Change in relatedness from baseline to 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. | Baseline, 3 months, 6 months | 
| Diet self-monitoring adherence | Number of days of complete dietary tracking summed over the 6-month study period. | Baseline to 6 months (daily) | 
| Weighing adherence | Number of days of self-weighing over the 6 month period. | Baseline to 6 months (daily) | 
| Physical activity self-monitoring adherence | Number of days of physical activity tracking over the 6 month period as measured by Fitbit tracker wear. | Baseline to 6 months (daily) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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behavioral intervention, JITAI (just-in-time adaptive intervention)