Evaluation of an Adaptive Intervention for Weight Loss Maintenance
Phase: NA
Conditions: Obesity
Sponsor: University of Florida

 
 
 
 
 
 
 
 
 
 
 
 
Evaluation of an Adaptive Intervention for Weight Loss Maintenance 
NCT04116853 
6/17/2024 

Protocol 
 
1. Project Title: 
  Evaluation of an Adaptive Intervention for Weight Loss Maintenance 
 
2. Investigators: 
Principal Investigator: 
Kathryn M. Ross, Ph.D., M.P.H. 
Associate Professor 
Department of Clinical and Health Psychology 
College of Public Health and Health Professions 
University of Florida 
P.O. Box 100165 
(352) 294-8433 
 
Co-Investigator(s): 
Lisa Anthony, Ph.D. 
Associate Professor 
Department of Computer and Information Science and Engineering 
Herbert Wertheim College of Engineering 
University of Florida 
P.O. Box 116120 
(352) 392-1200 
 
Jamie Ruiz, Ph.D. 
Associate Professor 
Department of Computer and Information Science and Engineering 
Herbert Wertheim College of Engineering 
University of Florida 
P.O. Box 116120 
(352) 392-1200 
 
Peihua Qiu, Ph.D. 
Professor 
Department of Biostatistics 
College of Public Health and Health Professions 
University of Florida 
P.O. Box 117450 
(352) 294-5911 
 
3. Abstract: 
 
     Participant engagement/attendance in existing extended-care interventions remains suboptimal, 
limiting effectiveness for long-term weight loss maintenance. We propose to evaluate a method for 
providing phone-based extended-care intervention adapted to participant needs (e.g., when 
participants are at “high risk” for weight regain as assessed by a predictive algorithm). We propose 
to conduct a randomized controlled trial assessing the impact of phone-based extended care 
delivered on an ADAPTIVE (only when indicated via our algorithm or when requested in-app by 
participants) vs. STATIC (pre-scheduled, once-per-month frequency used in existing extended-care 
programs) schedule on weight loss maintenance. As we propose to study weight loss maintenance, 
a key design consideration was to only randomize participants who have been successful with initial 
weight loss.1 Similar to existing maintenance trials,2,3 we will provide participants with an initial 
group-based gold-standard behavioral weight management program and then randomize 
participants who successfully achieve a clinically-significant weight loss between baseline and 
Month 4 (defined by the Institute of Medicine4 as a reduction in weight of ≥ 5% from baseline).  

 
4. Background: 
     Obesity remains a substantial public health challenge in the United States. While behavioral 
lifestyle interventions have been demonstrated to produce weight losses of 8-10% in adults with 
overweight and obesity,5 long-term outcomes are suboptimal.1 Following the end of initial treatment, 
individuals typically regain 1/3 to 1/2 of lost weight within a year and gradually return to baseline 
weight in 3-5 years.6 Research has demonstrated, however, that individuals who are able to 
continue to adhere to weight management behaviors can successfully maintain their weight loss 
long-term,5,7 implicating non-adherence to the eating and activity changes that produce weight loss 
as the primary mechanism for this weight regain.1,8,9 
     As a result, current clinical guidelines now conceptualize obesity within a chronic disease 
“continual care” model, necessitating long-term treatment provision.2,8,10,11 Existing “extended-care” 
programs typically provide long-term support via monthly sessions (delivered in-person or via 
telephone) and have demonstrated significant improvements in adherence to behavior change and 
less weight regain compared to no-contact control.12 While these effects have been statistically 
significant, the impact of existing programs on weight regain has been modest (around 1.5 kg less 
regain vs. control at 24 months)13 and there tends to be high individual variability in response to 
treatment.1  
     A key challenge to the effectiveness of extended-care programs has been continued participant 
engagement, typically operationalized as session attendance. Attendance has been consistently 
associated with long-term weight loss maintenance;3,12,14 however, attendance at monthly extended-
care sessions tends to be poor and declines over time.6 The once-per-month, static treatment 
schedules of existing programs may contribute to these suboptimal outcomes.15 Under this 
schedule, a participant experiencing a small lapse (e.g., failing to self-monitor dietary intake for 
several days) may not receive additional support for several weeks, by which time they may be 
experiencing a larger lapse (e.g., complete abandonment of self-monitoring and former dietary 
changes) and weight regain. Importantly, this cycle may result in participant disengagement and 
avoidance of treatment sessions due to feelings of frustration, shame, or embarrassment.16–18 In 
contrast, tailoring intervention delivery such that extended-care sessions are provided when 
individuals are at “high risk” for weight regain offers potential to disrupt this cycle and significantly 
improve program engagement, adherence to program goals, and long-term weight maintenance 
outcomes.  
     Dr. Ross is currently PI of a NIDDK-funded grant (R21DK109205) aimed at identifying and 
characterizing “high risk” periods of weight regain. For this project, Dr. Ross and Dr. Qiu (Co-I) first 
developed longitudinal change point mixture models19 to model the trajectory of weight loss and 
regain in 75 adults with overweight and obesity who took part in a 12-week Internet-based weight 
management program20 followed by a 9-month maintenance observation period during which no 
additional intervention contact was provided. Next, longitudinal multilevel models were used to 
identify factors proximally (on a week-to-week basis) associated with weight regain after initial 
weight loss. During the full study year (including the 9-month maintenance period), participants 
used a study website each week to self-report the number of days they monitored their weight, 
dietary intake, and total minutes of physical activity and completed an 11-item questionnaire asking 
them to rate, on 7-point Likert scales, factors that had been hypothesized previously to be 
associated with weight regain (e.g., positive mood, negative mood, stress, hunger, boredom with 
weight control efforts, temptation to eat foods not on their plan, temptation to skip planned physical 
activity, the degree to which physical activity choices were consistent with weight loss goals, the 
amount of effort that it took to stay on track, and the importance of staying on track, compared to 
other demands in life during the previous week). In a sub-sample of participants from the initial 
dataset who had successfully lost ≥ 5% of their baseline weight during the initial 12-week 
intervention (n=46), these results were used to fit regression tree models.21,22 These models were 
developed using R23 package rpart,24 using trimming methods proposed by Brieman,21 and 
predicted weight change the following week as a continuous response variable.  
     Drs. Ross and Qiu evaluated the optimized model in a test dataset consisting of the remaining 
28 study participants who continued to submit data during the 9-month maintenance period but 

whose data were not used to develop the predictive algorithm. In this separate test dataset, the 
algorithm demonstrated a sensitivity of 82.0% and a specificity of 30.4%. Taken together, these 
promising results suggested two key implications: 1) that weight regain can be reliably modeled and 
predicted, and 2) that this optimized predictive algorithm demonstrated good performance both in 
the initial training and separate testing datasets.  
     In the current study, we propose to evaluate an innovative method of providing phone-based 
extended-care treatment adaptive to participant needs. The proliferation of smartphones and 
mHealth apps has allowed for the development of new, adaptive treatment models aimed at 
providing intervention when it is needed most.25 Monitoring early signals of weight regain via an 
mHealth app will allow us to tailor intervention delivery at a previously-impossible level, via a 
method that is convenient and acceptable to participants. The dataset resulting from the current trial 
will be unique in terms of both scope and resolution, allowing us to build innovative behavioral 
models to inform future just-in-time adaptive intervention development.      
 
5. Specific Aims: 
Aim 1: Test the hypothesis that ADAPTIVE participants will experience significantly less weight 
regain than STATIC participants between Month 4 (randomization) and Month 24.  
 
Aim 2: Test the hypothesis that, compared to STATIC, a significantly greater proportion of 
ADAPTIVE participants will maintain clinically significant (≥ 5% from baseline4) weight losses at 
Month 24.  
 
Exploratory Aims: We propose to 1) use daily weight data collected via our mHealth app to model 
differences in weight trajectories between groups; 2) investigate potential treatment mediators (e.g., 
treatment engagement/session attendance and adherence to diet, physical activity, and self-
monitoring goals); 3) use the rich dataset collected via our mHealth app to develop dynamic models 
of weight loss/regain and to investigate additional proximal predictors of weight-related behaviors, 
identifying potential decision points and tailoring variables for future just-in-time adaptive 
intervention development.  
 
6. Research Plan: 
Inclusion Criteria 
- Age 18-70 
- BMI 30.0-45.0 kg/m2 
- ≤ 396 pounds (due to scale limit) 
- Own a smartphone [Apple iPhone (5s or newer) or Android smartphone (KitKat OS 4.4 or 
newer)] with a cellular and data plan 
- Lose ≥ 5% of baseline weight during the initial weight loss intervention (Month 0 to Month 4) 
- Willing to complete a phone-based maintenance program 
- Completion of baseline assessment measures 
     Exclusion Criteria 
      - History of bariatric surgery 
      - Current use of weight loss medications 
      - Weight loss of ≥ 10 lb in 6 months prior to screening for initial intervention enrollment 
      - Physical limitations that prevent walking ¼ mile without stopping 
      - Currently pregnant 
      - Currently breastfeeding 
      - Less than 1 year post-partum 
      - Plans to become pregnant within the study period 
      - Lack of written approval for participation from potential participant’s physician if the participant 
has been diagnosed with type 2 diabetes, hypertension, or has a history of coronary heart 
disease 
      - More than one participant per household (enrollment limited to one participant per household) 

      - Medical conditions that contraindicate weight loss or prevent completion of the study (e.g., 
current diagnosis of cancer or terminal illness, dementia, etc.) 
      - Unable to complete the two-year study (due to plans to relocate during the study period, etc.) 
      - Unwilling or unable to provide informed consent 
      - Unable to read English at the 5th grade level 
      - Unwilling to accept random assignment 
      - Unwilling to use the study app 
      - Unwilling to travel to initial intervention sessions 
      - Participation in another randomized research project 
      - Other conditions which in the opinion of the Principal Investigator would adversely affect   
        participation in the trial 
 
Recruitment and Screening 
     Recruitment. Based on experience in previous trials, we anticipate needing to screen 
approximately 1230 people to obtain a sample of 430. Participants will be recruited using 1) flyers, 2) 
in-person lectures and events, 3) contacting individuals who agreed to be recontacted for future 
research by signing a Consent2ShareThe Consent2Share process is a part of the University of 
Florida (UF) Clinical and Translational Science Institute’s (CTSI) Integrated Data Repository, a 
database organizing clinical information across UF Health’s clinical and research programs26, 4) 
outreach to local employers/businesses with IRB-approved materials, 5) newspaper, newsletter, 
print, and radio ads, 6) UF Health Studies website, 7) Direct mailings using publicly available mailing 
lists, 8) IRB-approved flyer shared via Nextdoor, a closed neighborhood-based social media site that 
allows neighbors to share important information, alerts, and updates with fellow community 
members,9) ResearchMatch.org, a national electronic, web-based recruitment tool that was created 
through the Clinical and Translational Science Awards Consortium, and 10) Facebook posts via local 
businesses, organizations, and churches using IRB-approved materials.  
     Phone Screens. Potential participants who call or email us for more information will receive a 
description of the study and will be asked to complete a brief phone screen questionnaire assessing 
for basic eligibility criteria (e.g., age, BMI, history of bariatric surgery, medical conditions that would 
contraindicate weight loss). Potentially eligible participants will be asked to attend an orientation visit 
in order to learn more detailed information about the study and complete final measures to determine 
if they are eligible to participate. Participants will be asked to select from a range of days/times to 
attend this orientation visit, and will be emailed confirmation of their selected day/time. 
    Orientation and final eligibility screening. Participants who meet initial eligibility criteria as 
assessed via the phone screen will be invited to attend an orientation visit. These visits will be 
conducted in small groups, and will begin with a discussion of the pros/cons of taking part in research 
and then discuss specific details of the current study (including but not limited to intervention 
protocol, the number and timing of follow-up assessment visits, and risks and benefits of taking part 
in the trial). If social distancing procedures are in effect, the orientation visit will take place by Zoom 
UFLPHI with e-consenting via REDCap. Potential participants will be given the opportunity to 
privately ask study staff any remaining questions that they have and then, if they remain interested, 
will be asked to provide written informed consent.  
     Screening Visit. After signing written informed consent, participants will complete baseline 
screening measures (see Table 1). If social distancing procedures are in effect, a study-provided 
scale will be mailed to participants for weight to be measured. At this time, participants will be asked 
to indicate what days/times they are available to attend intervention groups. Participants will be 
contacted via phone and informed of their final eligibility. During this call, participants who remain 
eligible for the initial weight loss program will be informed of their group day/time.  
   Baseline (Month 0) Assessment Visit. The Month 0 assessment visit will take place before the 
lifestyle weight management program. Once participants have completed baseline measures, they 
will begin the initial weight loss program. 
     Eligibility for the Maintenance Program. Eligibility for the randomized controlled trial of the 
ADAPTIVE versus STATIC maintenance program will be determined after the Month 4 assessment 
visit. Percent weight change from the Month 0 assessment to the Month 4 assessment will be 

calculated; participants who lose ≥ 5% of their Month 0 weight at Month 4 will remain eligible for the 
maintenance trial.  
 
Intervention and Randomization 
     Initial Weight Loss Program. All participants will be asked to complete a gold-standard 16-week 
lifestyle weight management program.10 Similar to existing protocols, this initial intervention will be 
delivered via in-person group classes of 10-20 participants, led by trained Group Leaders with a 
bachelor’s or master’s degree in nutrition, psychology, exercise science, or a related field.3,5,27 In the 
event of University closures, emergencies, or while social distancing procedures are in effect, this 
initial intervention will be delivered by Zoom UFLPHI. Zoom UFLPHI does not have access to 
identifiable health information and will protect and encrypt all audio, video, and screen sharing data. 
Meeting entry will require passwords which will be sent to participants separately from the meeting 
link. Intervention content for this 16-week program has been adapted from materials used in the 16-
session initial treatment program in Rural LITE28 and the 16-session “core curriculum” of the Diabetes 
Prevention Program.29 Groups will meet weekly for 16 weeks. 
     Throughout the 16-week program, participants will be encouraged to follow a nutritionally-
balanced reduced calorie diet (ranging from 1,200 to 1,800 kcal/day10 based on starting weight). 
Further, participants will be encouraged to gradually increase engagement in physical activity to 
reach ultimate program goals of 10,000 steps per day30 and 200-300 minutes per week of moderate-
intensity activity10,31 such as brisk walking. Consistent with current clinical guidelines for the treatment 
of obesity,10 these eating and activity goals were designed to result in a weight loss of 1-2 lbs per 
week.  
     Participants will be asked to self-monitor weight daily, using a study-provided BodyTrace scale. 
Participants will be asked to self-monitor caloric intake and physical activity via the commercial 
FatSecret mobile app (provided free of charge to participants). This application can be accessed by 
participants via web (https://www.fatsecret.com/) or via smartphone application. At the first study 
intervention session, participants will be asked to download this application on their mobile devices 
and will be guided on how to set up accounts using either their preferred email address or a study-
generated email address with no direct link to identifiable information. Participants will then be shown 
how to use this application to record their body weight, physical activity, and caloric intake each day. 
Participants will also be given guidance on how to protect their privacy and confidentiality using study 
devices and smartphone applications (e.g., suggesting using device encryption, using secure 
passwords and setting up automatic lock screens, and avoiding submitting personally-identifiable 
information through the applications).  
 
     Randomization. Participants who successfully achieve weight losses of ≥ 5% of initial body 
weight during the initial 16-week weight loss intervention (defined as change in assessment-
measured body weight from Month 0 to Month 4) will be eligible for randomization for the 
maintenance program. After determining eligibility, participants will be randomized using a 1:1 
allocation scheme by the study statistician (Dr. Qiu), stratified by initial weight loss (due to the known 
association between initial weight loss and longer-term maintenance,32,33 participants will be 
categorized by whether initial weight loss was ≥10% or < 10%). Participants will be notified of their 
inclusion/exclusion and asked to return for one in-person study visit to be informed of their 
randomization (see full description below). This process will take place by phone if social distancing 
procedures are in effect. 
 
     Extended-Care Maintenance Intervention.  All participants who are randomized at Month 4 will 
be asked to attend a single in-person study visit where they are informed of their study 
randomization, asked to provide general availability for extended-care maintenance intervention 
phone calls, and asked to download the MyTrack+ smartphone application developed by our study 
team and will be taught how to use this application. At this time, participants will again be given 
guidance on how to protect their privacy and confidentiality using study devices and smartphone 
applications (e.g., suggesting using device encryption, using secure passwords and setting up 
automatic lock screens, and avoiding submitting personally-identifiable information through the 
applications). Participants will be asked to use the MyTrack+ application to launch FatSecret, 

allowing them to continue to self-monitor their weight, physical activity, and caloric intake each day. If 
social distancing procedures are in effect, this visit will take place by phone.  
MyTrack+ will link with the FatSecret application through an API link, using a de-identified study ID to 
link participant self-monitoring data and display this data within the MyTrack+ application. Further, 
MyTrack+ will send prompts to study participants asking them to complete brief questionnaires (see 
full description in the measures section). All randomized participants will receive extended-care 
intervention delivered via phone; however, the frequency/timing of these calls will vary between the 
ADAPTIVE and STATIC conditions. Similar to protocols for phone-based intervention sessions 
previous trials conducted by the PI34 and the ongoing Rural LEAP trial, each phone-based extended-
care session will last for approximately 10-20 minutes. Each call will be initiated by the interventionist, 
and will begin with a brief check-in followed by a discussion of any barriers experienced by 
participants in meeting their weight maintenance goals. To address these barriers, interventionists 
will guide participants through a five-step problem solving model,35 including 1) positive problem 
orientation (developing a positive mindset), 2) problem definition (the concrete definition of the 
problem; i.e., the who, what, when, where, and why of the problem), 3) generation of alternatives (a 
brainstorming session where the goal is to produce the maximum number of potential solutions), 4) 
decision making (the evaluation of potential solutions by two key criteria: “will this work if I do it?” and 
“what are the odds I’d actually do it?”) and 5) solution implementation and verification (i.e., trying out 
the proposed solution and evaluating effectiveness). Each call will end with a formal goal setting 
session wherein participants are encouraged to set SMART (Specific, Measurable, Achievable, 
Relevant, and Time-limited) goals.36–39 Interventionists will keep notes on each session so that 
he/she can check in with each participant during the next call regarding success toward stated goals 
(and success of any problem solutions identified). Further, the start and end time of each call will be 
documented to monitor the frequency/duration of intervention calls, and each call will be audio 
recorded to monitor intervention fidelity. 
    If the participant cannot be reached for a call, the interventionist will leave a voicemail asking the 
participant to return his/her call. Interventionists will make up to 5 “call attempts” on various 
days/times (ideally no more than one call per day) if unsuccessful. If the participant cannot be 
contacted after 5 attempts, the interventionist will attempt to contact the individual via email to note 
difficulty reaching the participant. If the interventionist does not receive a response to the email within 
a week, he/she will send a certified letter to the participant’s home address noting the difficulty 
contacting them and to encourage continued participation in the study. 
 
     STATIC Extended-Care Program. Participants randomized to the STATIC maintenance program 
will receive the extended-care intervention phone calls described above on a fixed, once-per-month 
schedule. The initial call date/time will be scheduled during each participant’s randomization 
notification call. At the end of the initial phone session (and each session thereafter), interventionists 
will confirm the next call’s scheduled day/time (one month after the current call, at the same time) 
and reschedule if necessary (e.g., participant time conflicts due to work or travel).  
 
     ADAPTIVE Extended-Care Program. For participants randomized to the ADAPTIVE 
maintenance program, the extended-care intervention phone calls described above will be delivered 
only if either 1) an algorithm developed by our study team detects that a participant is at “high risk” 
for weight regain or 2) the participant self-initiates a request for a session by navigating to a “support” 
section of the app. The algorithm that will be used to trigger intervention is provided in Figure 1; the 
collection of data required for this algorithm will be conducted via MyTrack+ and is described in detail 
in the measures section. 

Once intervention has been triggered (via our algorithm or an in-app support request), a notification 
will be automatically 
sent to the 
participant’s 
interventionist via a 
secure email, and the 
interventionist will 
initiate an intervention 
call as soon as 
possible (i.e., at the 
next day/time the 
participant indicated 
they were generally 
available for 
intervention calls). On 
weeks that 
intervention is not 
triggered via our 
algorithm or via in-app 
participant request, no 
additional intervention 
contact will be 
provided.  
 
     Interventionist 
Training. 
Interventionists will 
have a bachelor’s or master’s degree in nutrition, psychology, exercise science, or a related field. All 
interventionists will undergo training and certification in the intervention methods and treatment 
protocols prior to the start of the weight loss intervention. Interventionists will be provided with a 
comprehensive treatment manual (detailing session-by-session objectives and methods) and will be 
asked to attend a two-day workshop prior to the start of intervention. Prior to the end of the initial (in-
person, group-based) weight management groups, all interventionists will be asked to attend a 
follow-up workshop focused on procedures for the ADAPTIVE and STATIC conditions and protocol 
for the phone-based extended-care sessions. 
     Weekly intervention team meetings led by the PI and the Research Coordinator will be dedicated 
to review of intervention materials, practice in intervention application (e.g., role play and rehearsal 
activities), and case management reviews of individual participant progress. All intervention sessions 
(both initial, in-person group sessions and extended-care phone sessions) will be audio recorded and 
random reviews will be conducted by to monitor fidelity and assess whether interventionists require 
additional training. At the end of the trial, 10% of all extended-care phone calls will be randomly 
selected and assessed for fidelity (using a fidelity checklist) by study staff.  
 
     Assessment Schedule and Measures      
     Assessments will be conducted at Month 0 (baseline), Month 4 (end of the initial weight loss 
intervention), Month 12, and Month 24 (see Table 1). Assessments will be conducted by trained 
study staff members masked to maintenance condition. All self-report questionnaires will be 
completed online via the University of Florida’s REDCap (Research Electronic Data Capture)40 
system. 
Height. Trained study staff will measure participant height via stadiometer, with participant shoes 
removed. If social distancing procedures are in effect, a self-reported height will be recorded.  
Assessment weight. Participant body weight will be measured at the screening visit as well as all 
assessment visits by trained research staff using calibrated Tanita digital scales, with participants in 
light indoor clothing, with pockets emptied and belts and shoes removed. If social distancing 
procedures are in effect, weight will be measured using a study-provided scale. 
Figure 1. Final ADAPTIVE Treatment Delivery Algorithm 

Demographics. Participant demographic information will be collected via a brief demographics 
questionnaire completed at the screening visit. 
Contact Information. Participant contact information will be collected via questionnaire at the 
screening visit. Contact information will be updated with any changes during the Month 4 and Month 
12 visits. 
Weight Loss History. Weight loss history will be assessed via an 8-item self-report questionnaire 
completed at the baseline assessment visit.  
Weight Loss Self-Efficacy. Self-efficacy for weight loss will be assessed via the Weight Loss Self-
Efficacy Scale, an 8-item self-report questionnaire completed at all assessment time points.   
Weight Control Strategies. Use of common weight control strategies will be assessed via the Weight 
Control Strategies Scale, a 30-item self-report questionnaire completed at all assessment time 
points.   
Medical History/Update. Medical history will be collected at baseline via a self-report questionnaire. 
Updates to this history will be collected via a self-report questionnaire delivered at all remaining 
assessment visits.  
Dietary Intake. Dietary intake will be assessed at all assessment time points using Automated Self-
Administered 24-hour dietary recalls (ASA24)41 completed by participants via the National Cancer 
Institute (NCI) respondent website. At each assessment time point, participants will be asked to 
complete three ASA24 recalls. Participants will be asked to complete these recalls on a schedule that 
is unknown to them; they will be informed that they will be contacted by study staff via email on the 
day that a recall is scheduled to be completed. At this point, participants will be asked to log on to the 
NCI ASA24 respondent website and to report all foods/drinks consumed on the prior day. Recalls will 
be scheduled by study staff so that each participant completes at least 2 recalls reflecting weekday 
intake and 1 recall reflecting weekend intake during each assessment time point.  
Cost Analysis Survey. Healthcare costs will be assessed at all assessment time points using a 21-
item self-report survey. 
Sedentary Behavior Questionnaire. Weekday and weekend sedentary behavior will be assessed at 
all assessment time points using a 16-item self-report questionnaire. 
Munich Chronotype Questionnaire. Sleep duration and timing will be assessed at Month 0 using a 
30-item self-report questionnaire. 
Social Norms Scale. Social norms for unhealthy eating and physical inactivity will be assessed at 
Month 0 using a 28-item self-report measure. 
International Physical Activity Questionnaire. The long format of this questionnaire is a 27-item self-
report survey which will be used to assess physical activity at all assessment time points. 
Supportive Accountability Questionnaire. Social support and supportive accountability will be 
assessed at all assessment time points using a 33-item self-report measure. 
Perceived Stress Scale. Perception of stress will be assessed at all assessment time points using a 
10-item self-report measure. 
Palatable Eating Motives Scale. Reasons for eating palatable foods outside of hunger will be 
assessed at all assessment time points using a 20-item self-report measure. 
Meal Planning Questionnaire (MPQ). The MPQ is a new self-report questionnaire that has been 
developed by our study team in order to assess frequency with which individuals plan meals in 
advance. 
The MPQ will be administered at all assessment time points. 

EQ-5D-5L. The EQ-5D-5L is a 6-item self-report measure of health-related quality of life which will be 
administered at all assessment time points. 
OPTION Scale. The OPTION scale is a 10-item self-report measure of diet, physical activity, and 
sleep for parents of children under 18 years old which will be administered at all assessment time 
points. 
Body Image States Scale (BISS). The Body Images States scale is a 6-item self-report measure of 
body image 
evaluation. 
Physical 
Activity.  
Physical activity 
will be 
assessed at all 
assessment 
time points 
using a hip-
worn ActiGraph 
physical activity 
monitor. 
Participants will 
be given 
instructions to 
wear the 
monitor for 
seven days 
after each 
assessment 
time point.  
 
Self-
Compassion 
Scale. 
The Self-
Compassion 
Scale is a 26-
item self-report 
measure of trait 
levels of self-compassion which will be administered at all time points. 
 
Program Satisfaction Questionnaire. The program satisfaction questionnaire is a 16-item self-report 
questionnaire which will be administered at Month 24 to obtain participant feedback about the study. 
 
Data collected through the study.  
Audio Recordings of Intervention Sessions.  
Audio recordings of intervention sessions will be collected for training and supervision purposes and 
to monitor intervention fidelity. Audio recordings will be transcribed and de-identified for purposes of 
coding nutrition/activity related issues and interventions. Audio recordings will be collected via Sony 
Digital Voice Recorders (phone sessions will be recorded by connecting these recorders to a phone 
adapter). These recorders will be kept in locked filing cabinets within the PI’s locked research lab 
when not in use. Recordings will be downloaded to secure drives on the UF network (the Public 
Health and Health Professions P: drive under a secure folder only accessible to interventionists, the 
PI, and the study Research Coordinator) after each intervention session and deleted from the Sony 
Table 1. Schedule of Assessment Visits and Measures 
  
 
Assessment Time Point 
  
 
Initial 
Intervention 
Extended-Care  
Measure 
Screening 
Visit  
Month 
0 
Month 
4 
Month 
12 
Month 
24 
Anthropometrics 
 
  
  
  
  
   Weight (via Tanita digital scale) 
x 
x 
x 
x 
x 
   Height (via stadiometer) 
x 
  
  
  
Questionnaires 
 
  
  
  
  
   Demographics 
x 
  
  
  
   Contact Information 
x 
 
x 
x 
 
   Weight Loss History 
 
x 
  
  
  
   WEL-SF (Weight Loss Self-Efficacy)42 
 
x 
x 
x 
x 
   WCSS (Weight Control Strategies)43  
 
x 
x 
x 
x 
   Medical History/Update 
x 
x 
x 
x 
   ASA24 Dietary Recall41 
 
x 
x 
x 
x 
   Cost Analysis Survey 
 
x 
x 
x 
x 
   Sedentary Behavior Questionnaire44 
 
x 
x 
x 
x 
   Munich Chronotype Questionnaire45 
 
x 
 
 
 
   Social Norms Scale46 
 
x 
 
 
 
   International Physical Activity Questionnaire47 
 
x 
x 
x 
x 
   Supportive Accountability Questionnaire48 
 
x 
x 
x 
x 
   Perceived Stress Scale49 
 
x 
x 
x 
x 
   Palatable Eating Motives Scale50 
 
x 
x 
x 
x 
   Meal Planning Questionnaire 
 
x 
x 
x 
x 
   EQ-5D-5L51 
 
x 
x 
x 
x  
   OPTION Scale52 
 
x 
x 
x 
x 
   Body Image States Scale53 
 
x 
x 
x 
x 
   Self-Compassion Scale54 
 
x 
x 
x 
x 
   Program Satisfaction Questionnaire 
 
 
 
 
x 
Adherence/Other 
   Physical Activity (via ActiGraph)55 
           
x 
x  
x  
x  
   Session attendance 
 
Assessed Continuously 
   Weight (via in-home Bluetooth scale) 
 
Assessed Continuously 
   Self-monitoring (weight, dietary intake, activity) 
 
Assessed Continuously 
   Questionnaire data from MyTrack+ 
 
Assessed Continuously 

Digital Voice Recorder.  
Smart Scale Data. Throughout the initial 16-week intervention and until the final Month 24 study visit, 
participant weight will be tracked through study-provided BodyTrace smart scales. These scales use 
the cellular network to send participant weight data to BodyTrace servers, from which the 
investigators can directly download data. No identifiable information will be transmitted or stored on 
the BodyTrace servers; participants are identified only via a numeric study ID with no links to 
personally-identifiable information. Frequency of self-weighing will be used in our ADAPTIVE risk 
algorithm to determine whether intervention should be triggered (see Figure 1 for details).  
Data collected from FatSecret. Via the FatSecret API, we will download participant self-reported 
weight, physical activity, and dietary self-monitoring records (including food and drinks consumed 
along with portion size of these foods/drinks and information regarding kcal and 
macronutrient/micronutrient composition of these food/drinks). The FatSecret API does not provide 
timestamps of when participants self-monitor weight, caloric intake, or physical activity; however, our 
server will append time/day that data were downloaded to this dataset. MyTrack+ will sync with 
FatSecret in order to display summaries to participants (e.g., summaries of body weight, caloric 
intake, and physical activity over the past week). This data will be linked to participants only through 
a non-identifiable study identification number. Frequency of self-monitoring caloric intake will be used 
in our ADAPTIVE risk algorithm to determine whether intervention should be triggered (see Figure 1 
for details). 
Data collected from MyTrack+. Participants will be asked to respond to prompts to complete brief 
questionnaires via the MyTrack+ app. At the end of each week, participants will be prompted to 
respond to two questions in order to collect necessary data for the ADAPTIVE risk algorithm (see 
End of Week Questionnaire). Further, once each week (with participants unaware of the day that the 
questionnaire will be asked), participants will be asked to complete a 12-item questionnaire (see 
Weekly Questionnaire). Participants will also be able to launch FatSecret within the MyTrack+ app in 
order to enter weight, caloric intake, and physical activity. We will also collect usage data from this 
application in order to assess participant engagement. MyTrack+ will be connected to our research 
servers using only study identification numbers.  
 
Statistical Design and Power 
     The primary outcome for the proposed trial will be weight change from Month 4 to Month 24. This 
variable will be continuous, and analyses conducted during our team’s previous trials have 
demonstrated that weight change can be well modeled using a normal distribution.3 Thus, standard 
parametric techniques will be used. A longitudinal mixed model will be used to analyze the primary 
aim data, using treatment condition and time since study start as fixed effects. One primary contrast 
of interest will be tested for significance: weight regain between Month 4 and Month 24 in the 
ADAPTIVE vs. STATIC treatment conditions. Fixed effects will include randomization condition, time 
since study start, and initial intervention weight loss (as a binary variable representing whether initial 
weight loss was ≥10% or <10%, used to stratify randomization). Sensitivity analyses will be 
conducted to assess robustness of results under alternative assumptions related to missing data 
(including a missing not-at-random approach assuming that individuals who discontinue participation 
in the study prior to Month 24 regained an average of .3 kg/month, up to baseline weight3,54,55). 
     The secondary outcome for the proposed trial will be the proportion of individuals in each group 
maintaining a clinically-significant (≥ 5% weight loss from baseline/Month 0)4 at Month 24. Percent 
change will be calculated from assessment weights at Month 0 and Month 24, and participants will be 
categorized dichotomously as having weight losses at Month 24 of ≥ 5% or < 5% from baseline. 
Difference in proportion of participants maintaining a ≥ 5% weight loss will be assessed using a two-
tailed z-test for independent proportions.  
     As an exploratory aim, we intend to compare weight loss trajectory over time between the two 
groups. For this, we propose to use longitudinal mixed-effects modeling56–58 and the growth curve 
modeling59,60 to analyze weight change data observed at several different time points, where the 
within-subject data correlated is accommodated by the random-effects terms included in the 
longitudinal mixed-effects model and by a general covariance matrix in the growth curve model. 
These analyses will demonstrate differences in weight change between participants in the 

ADAPTIVE and STATIC groups over time. Changes in dietary intake, physical activity, and self-
monitoring adherence over time will be assessed using multilevel models for repeated 
measurements.57 Potential treatment meditators (e.g., intervention engagement, operationalized as 
the proportion of possible extended-care sessions attended, adherence to self-monitoring, and 
changes in dietary intake/physical activity) will be assessed using bootstrapping to estimate 
confidence intervals around indirect effects.61,62 Finally, the rich dataset collected via MyTrack+ 
(including time-stamped self-monitoring data (including not only frequency counts of self-monitoring 
behavior but also daily weight, caloric intake, and physical activity data) and ecological momentary 
assessment questionnaire data collected over a full two year study period) will be used to examine 
proximal predictors of change in weight and weight-related behaviors. Following the pragmatic 
framework developed by Nahum-Shani and colleagues,63 we propose to build dynamic models of 
weight loss and weight regain, identifying key tailoring variables and potential intervention options for 
future just-in-time adaptive interventions for weight loss maintenance.    
     The most recent clinical guidelines for the treatment of obesity (released as a joint report by the 
American College of Cardiology [ACC], American Heart Association [AHA] and The Obesity Society 
[TOS])10 define 2.5 kg as the minimal amount of weight loss associated with lowered risk of type 2 
diabetes, and further note that weight losses of this magnitude are associated with modest 
improvements in triglycerides, and modest reductions in blood pressure. Thus, similar to previous 
weight management trials powered to detect this smallest clinically-meaningful difference,3,28 sample 
size for the primary aim analysis was selected to provide a statistical power of .90 to detect a 
difference in weight change of 2.5 ± 5.5 kg between groups from Month 4 to Month 24. This resulted 
in an estimated 206 participants (103 participants per group). With SDs of 5.0 and 6.0, estimated 
power would be .946 and .845, respectively. Assuming a retention rate of 80% at Month 24, 258 
participants would need to be randomized at Month 4.  
    Based on our previous studies,3,20,28 we conservatively estimate that 60% of participants who 
complete the initial 16-week phone-based behavioral weight loss intervention will be eligible for 
randomization and ultimately randomized; thus, we propose to recruit 430 adults to take part in the 
initial weight loss program. Note that this sample size calculation is based on the planned contrast 
between groups at Month 24. With the observed data collected at the intermediate assessment times 
before Month 24, the calculated sample size should guarantee enough power for the longitudinal 
data analyses that include all observed data at different assessment times.  
     For the secondary aim, we propose to investigate the proportion of participants in each group who 
achieve a clinically-significant weight loss/maintenance defined by the more conservative Institute of 
Medicine4 threshold (≥ 5% from baseline weight). The current ACC/AHA/TOS Clinical Guidelines for 
the Treatment of Obesity10  note that maintenance of weight losses of ≥ 5% of baseline weight is 
associated with not only lower risk of developing type 2 diabetes, but also reductions in HbA1c of 
0.6% to 1.0%, reductions in need for diabetes medications, clinically meaningful reductions in fasting 
glucose, improvements in LDL and HDL cholesterol, reduction in use of lipid-lowering medications, 
and reductions in systolic and diastolic blood pressure of 3 and 2 mm Hg, respectively. Further, using 
this cut-off will allow us to compare our results to previous weight loss maintenance trials. Previous 
trials of phone-based extended-care interventions demonstrate that between 38% and 44% of 
participants maintain weight losses of ≥ 5% between Months 18 and 24.2,3,64,65 In assessing sample 
size needed and power for secondary aim analyses, we assume conservatively that 45% of STATIC 
participants will maintain clinically-significant4 weight losses of ≥ 5% at Month 24. Under an intent-to-
treat approach, including all randomized participants, we will assume any participant not returning for 
the Month 24 follow-up visit has not met this-cut off. With these assumptions, we assessed 
necessary sample size to power a 15%, 20%, and 25% difference between achievement of this 
clinically-significant cut-off in the ADAPTIVE and STATIC conditions. With a sample of 258 
randomized participants (the estimated sample size needed to adequately power primary aim 
analyses), estimated power would be .676 for a 15% difference between ADAPTIVE and STATIC 
participants (i.e., with 60% and 45% of participants maintaining this clinically-significant cut-off, 
respectively); power for a 20% difference would be .902 and power for a 25% difference would be 
.985.  
      
 

Data and Safety Monitoring Plan 
     Given that participants are not masked to intervention condition, vulnerable populations will not be 
enrolled, and this is a Phase II trial with minimal risks, we propose that the safety monitoring of the 
study will be conducted by Dr. David Janicke, the study Safety Officer. Dr. Janicke is a clinical 
psychologist and a Professor and Associate Department Chair in the Department of Clinical & Health 
Psychology at the University of Florida. His previous experience as principal investigator or co-
investigator on over 15 clinical trials (many of which focused on behavioral approaches to improving 
diet and physical activity) renders him well qualified to review aspects of the progress and safety of 
this trial. Information regarding progress with recruitment, retention at assessment sessions, reasons 
for dropout, and adverse events will be submitted once per year to the Safety Officer for review. After 
reviewing this data, the Safety Officer will indicate in writing to Dr. Ross and NIH whether the study is 
progressing appropriately or changes are needed. At any point during the trial, the Safety Officer can 
recommend that a phone call be held to discuss any issues with the progress or safety of the trial.  
     All of the staff involved in data collection will be trained by the Principal Investigator (Dr. Ross) 
and/or the Research Coordinator and must demonstrate competence in administering all measures. 
Study Research Assistants (masked to treatment condition) will review all assessment data for 
accuracy and completion, and the Lab Manager along with the Graduate Assistant in 
Biostatistics/Data Manager will monitor data entered into the REDCap system by participant self-
report or by research staff and completion of ASA2441 recalls via the National Cancer Institute online 
ASA24 portal. Participants will be re-contacted to provide missing data or to clarify ambiguous 
responses. Range checks will be built into the data entry procedure to alert staff to data that should 
be clarified. Under the supervision of the Research Coordinator and the Lab Manager, a complete 
double-entry verification procedure will be used for all data entered to ensure accuracy. Under the 
supervision of the Co-Investigator/study statistician (Dr. Qiu), the Graduate Assistant in 
Biostatistics/Data Manager will conduct error checking and preliminary analyses of all data to further 
ensure accuracy. Any existing hard copies of data will be stored in a locked filing cabinet in a locked 
room, and electronic data files will be password protected and backed up on a secure UF server. 
     All participant records and assessment data will be treated as confidential, including participants’ 
names and the fact that they are participating in the study. Participant information collected by the 
research staff will contain only a non-identifiable study ID. A separate database linking study ID and 
participant identifiers (name, address, contact names and addresses) will be maintained in an 
encrypted, password-protected file stored on a secure UF server. Records and assessment data will 
be safeguarded according to the policy of UF’s IRB, which promotes the protection of confidential 
health information.  
    All study workstations will be managed by UF Information Technology (IT), (workstations located in 
the Health Professions, Nursing, and Pharmacy building and the Dental Ground floor area of UF 
Health Shands Hospital will be managed by the College of Public Health and Health Professions IT, 
and workstations located in the Department of Computer and Information Science and Engineering 
(CISE) will be managed by CISE IT), patched regularly, will have lock screens that automatically 
engage at 15 minutes idle time. All study workstations will utilize GatorLink accounts for access, and 
study databases stored on these workstations will be encrypted and password protected. Only IRB-
approved research team members will have access to study databases. Data will be encrypted 
during transfer from BodyTrace and FatSecret and when stored on UF servers. Participants will be 
assigned a unique, non-identifiable study identification number that will be used to link data from 
BodyTrace, FatSecret, MyTrack+, REDCap, and study databases.   
    Additional safeguards are in place to protect participant questionnaire data entered via REDCap. 
The REDCap platform is managed by the UF Clinical and Translational Science Institute and only 
IRB-approved research team members will have access to the platform. REDCap system security 
includes: secure logins, data encryption at rest, remote system logging and configuration and change 
management. Each team member is granted access to REDCap through a secure login, and audit 
trails are available by username. Data backups are encrypted both in flight and at rest. 
 
 
 

7. Possible Discomforts and Risks: 
 
a. Potential Risks 
 
The extensive literature on behavioral interventions for weight loss shows that there are very 
few risks associated with this type of intervention, provided that energy intake exceeds 1,000 
kcal/day.66 In the proposed study, participants are encouraged to follow a balanced diet above this 
minimum amount (our targeted goals encourage participants to consume 1,200 to 1,800 kcal/day, 
based on initial weight). This study asks some participants to monitor their weight daily; while this 
may raise concerns of negative psychological reactions (e.g., lower body image, depression), 
research has demonstrated that daily self-weighing does not negatively impact individuals.67 There 
is a small potential risk of musculoskeletal injury associated with the exercise component of the 
intervention. In the Diabetes Prevention Program, on which the current initial intervention is based, 
the occurrence of musculoskeletal injuries was 3% higher in the lifestyle intervention group than in 
the placebo control condition.68 In our studies, we have found that the risk of injury from exercise 
can be minimized through the use of moderate- rather than high-intensity exercise activities. The 
procedures to minimize risk are described in further detail below. 
 
b. Protection Against Risks 
The BMI cut-offs were chosen using current clinical guidelines, which recommend behavioral 
weight management intervention for adults with BMI ≥ 30 kg/m2. Individuals with BMIs ≥ 45 kg/m2 
and individuals over the age of 70 years have greater medical comorbidities and require medical 
supervision during weight loss attempts; therefore, these individuals will be excluded from 
participation but will be provided with appropriate referrals. The remaining exclusion criteria are 
included for the safety of participants. 
The behavioral weight management intervention will target a nutritionally-balanced energy 
intake that exceeds 1,000 kcal/day, thereby reducing the risks associated with a very-low-calorie 
diet.10 Throughout the study period, participants will self-monitor dietary intake via the MyTrack+ 
app. During the initial 16-week intervention, study interventionists will review these records weekly, 
in consultation with the study team’s Registered Dietitian (R.D.). Participants who are observed to 
be consuming nutritionally inappropriate intakes with regard to either the quantity or quality of foods 
consumed will receive individualized counseling to assist them in achieving appropriate intake. Any 
records that demonstrate food intake for < 800 kcal/day (the cut-point for “very low caloric intake,” 
which typically requires medical monitoring10) for > 3 days in a week will be reviewed directly by the 
R.D., and an individual consult will be provided to the participant to assess risk. The R.D. will 
provide counseling as appropriate, and this additional intervention contact will be documented.  
 
During the maintenance trial, it is likely that days with self-monitoring records demonstrating 
caloric intake totals of < 800 kcal represent days in which self-monitoring records were not fully 
completed. We counsel participants to record even just a meal or two if they cannot record the 
entire day. As a result, setting a rule to trigger nutritional counseling when MyTrack+ records 
demonstrate intake < 800 kcal/day is likely to lead to a large number of false triggers in both 
ADAPTIVE and STATIC maintenance programs. Therefore, during the maintenance trial, we 
propose to monitor this intake concurrently with weight change; similar to the algorithm we use to 
trigger additional intervention contact in the ADAPTIVE condition, we will program an automated 
monitoring system that will trigger a record review and consult by the R.D. if both of the following 
conditions are met: 1) a participant demonstrates a weight loss of ≥ 1.5% in a 7-day period, 2) a 
participant demonstrates > 3 days with caloric intake < 800 kcal/day. This safety monitoring will 
occur during the maintenance trial for participants in both the ADAPTIVE and STATIC conditions. 
 
Prior to enrollment, participants who report diagnoses of type 2 diabetes, hypertension, or 
history of coronary heart disease will be asked to obtain written approval for participation from their 
physician, and any changes in medication required by reduction in caloric intake or weight will be 
managed by the participant’s physician. 
 
All written forms that contain identifying participant information will be stored in a locked, secure 
area, and only authorized personnel will have access to the records. Similarly, the computerized 
database housed in the University of Florida Clinical and Translational Science Institute (UF CTSI) 

will remain encrypted, and access will require password-protected authentication. Computer files 
will not include the participant’s name; instead, a subject identification (ID) number will be used as a 
means of providing additional security. All audio recordings will be transferred from the recording 
device to UF servers immediately after each session, and the file deleted from the recorder. Audio 
recorders will be stored between uses in a locked cabinet in a locked office.  
 
The current study collects data through a third-party smart scale (developed by BodyTrace, Inc.) 
and third-party smartphone app (developed by FatSecret). To protect participant privacy and 
confidentiality, no identifiable information will be provided to BodyTrace, Inc.; participants will be 
identified only by a study identification number. If social distancing procedures are in effect, 
participants will be notified in the informed consent document that their name and address will be 
provided to BodyTrace, Inc. for scale shipping purposes. Participants will be given the choice to set 
up their accounts with FatSecret using either their personal email address or a study-generated 
email address, and will be advised to refrain from sharing personally-identifiable information through 
the FatSecret application. Data from the FatSecret application will be downloaded to our servers 
linked with an assigned study identification number. Our study-developed smartphone application 
(MyTrack+) will further identify participants through a study identification number. Data will be 
encrypted during transfer between BodyTrace, Inc., FatSecret, and MyTrack+ and our UF-based 
research servers, and while stored on our servers. All computer workstations will utilize GatorLink 
accounts for access. All study databases will be encrypted and password-protected. Only IRB-
approved research team members will have access to study databases. 
 
8. Possible Benefits: 
 
The potential benefits to participants include improvements in the quality of nutritional intake, 
increased physical activity, and weight loss. In individuals with obesity, such changes are often 
associated with improvements in health. Thus, the potential health benefits associated with 
participation appear to outweigh the small potential risk associated with lifestyle intervention. 
 
At the end of each 2-year study period, participants in the maintenance program will be provided 
with a summary of their individual weight and data collected over the course of the maintenance 
program. 
 
The development of successful approaches to the long-term management of obesity would 
represent an important scientific contribution and a benefit to society. 
 
9. Conflict of Interest: 
There are no conflicts of interest for any of the investigators.   
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

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