Abstract
BACKGROUND: The Confident Moves (CM) intervention is a newly developed, theory-based online intervention to promote physical activity (PA) in adults with obesity by providing a set of theory-informed behavior change techniques intended to enhance participants' self-efficacy for PA. Uncertainties remain regarding the feasibility and acceptability of implementing the CM intervention in an obesity care center, where additional supports (e.g., meal plans, appetite suppressants) are typically provided. The objective of this longitudinal pilot trial was to investigate the feasibility and acceptability of implementing the CM online intervention for adults with obesity recruited from a local weight management center in the United States of America, in preparation for a future definitive randomized controlled trial (RCT). METHODS: This study was designed as a prospective, individually randomized, two-arm pilot trial. Data were collected across three waves over a period of up to 14 weeks, depending on each participant's progression. Thirty participants were randomized to either the CM intervention group or the usual care group. The survey battery assessed demographic characteristics, anthropometric measures, self-efficacy, and acceptability. Free-living PA was objectively measured using a research-grade accelerometer (ActiGraph wGT3X-BT). Primary outcomes included: (a) participation rate, (b) engagement behavior in CM, and (c) a preliminary estimate of the CM intervention's effect size on PA. Secondary outcomes (e.g., consent rate) were also evaluated. Predetermined threshold values outlined in a protocol guided the assessment of each outcome. Data analyses included both quantitative and qualitative approaches. RESULTS: Supporting evidence (i.e., meeting or exceeding the predetermined upper threshold) was found for all primary outcomes (i.e., participation rate, engagement behavior in CM, and preliminary effect size of CM on PA). Mixed evidence (i.e., meeting or exceeding the upper threshold, within the middle threshold range, or below the lower threshold) was observed for secondary outcomes. CONCLUSIONS: This longitudinal pilot trial supports the viability of a future definitive RCT of the CM intervention and highlights areas for refinement in study procedures, intervention duration, and assessments. The findings also suggest important directions for optimization and real-world implementation, particularly through partnerships with obesity care. TRIAL REGISTRATION: ClinicalTrials.gov, NCT05935111, registered 7 July 2023.