Examining Valence-based Effects in Self-Monitoring Feedback Messages

This micro-randomized factorial trial is designed to provide information about how to optimize self-monitoring feedback within a behavioral weight management intervention. All participants will attend a "Weight Loss 101" session that covers foundational weight loss education and behavioral skills training. During this session, they will also learn how to use study-provided tools to track their dietary intake, physical activity, and weight.

Each weekly feedback message will be composed by a trained interventionist. Participants will be randomized each week to one of the two conditions to examine how the tone and composition of feedback messages impact participant behaviors and weight loss.

The main questions that this study aims to answer are:

• How does the composition of supportive feedback and ideas for potential changes in dietary or physical activity behaviors impact weight loss.
• How is this feedback affected by individual or contextual factors?

Inclusion criteria

• Age greater than or equal to 18 years
• BMI greater than or equal to 25.0 kg/m2
• Weight less than or equal to 175 kg (due to scale limit)
• Own a smartphone compatible with Fitbit (e.g., an Apple iPhone running iOS 16.4 or higher or Android smartphone running Android 11 or higher) with a cellular and data plan

Exclusion criteria

• Weight greater than 175 kg (due to a weight limit of the study-provided scale)
• Smartphone device owned deemed incompatible with the Fitbit App
• History of bariatric surgery or plans to obtain bariatric surgery during the study period
• Current use of weight loss medications, or use of weight loss medications in the 6 months prior to initial pre-screening
• Currently participating in a weight-loss program
• Weight loss of greater than or equal to 10 lbs in the 6 months prior to initial pre-screening
• Physical limitations that prevent walking at a brisk pace for at least 10 minutes without stopping
• Use of a pacemaker or other implanted medical device
• Currently pregnant
• Currently breastfeeding
• Less than 1-year post-partum
• Plans to become pregnant within the study period
• Lack of written confirmation that the potential participant has discussed study participation with their physician if they have been diagnosed with diabetes, hypertension, or has have a history of coronary heart disease
• One or more study participants living in the 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.)
• Recent (in the past 6 months) changes in medications that affect weight
• Self-reported eating disorder within past 5 years
• Unable to complete the 17-week study (due to plans to relocate during the study period, etc.)
• Unable or unwilling to provide informed consent
• Unable to read English at the 5th grade level
• Unwilling to accept random assignment
• Unable or unwilling to download the study smartphone application, wear the physical activity monitor, or use the study e-scale
• Failure to complete baseline assessment measures
• Failure to complete at least 4 out of 6 days of self-monitoring dietary and weight self-monitoring during the behavioral run-in period
• Any other condition(s) which, in the opinion of the Principal Investigator, would adversely affect participation in the study