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.
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Background
Obesity and overweight are conditions in which excess body fat accumulates to a level that can harm health and contribute to serious non-communicable diseases, including cardiovascular disease, type 2 diabetes, and certain cancers [1,2,3]. Engaging in physical activity (PA) is recommended for adults with obesity or overweight because it positively impacts health outcomes, including improved metabolic, cardiovascular, and mental health, even without weight loss [4,5,6,7]. For textual (e.g., word limits) and conceptual (e.g., eligibility) simplicity, we will simply refer to “adults with obesity or overweight” as “adults with obesity” from this point forward. This wording aligns with an international obesity prevention and management approach, which often views overweight as a “pre-obesity stage” [8].
Research consistently has shown that many adults with obesity (≥ 57%) do not meet global PA guidelines [9, 10], for example, engaging in 150–300 min of moderate-intensity activity, 75–150 min of vigorous-intensity activity, or an equivalent combination of both each week [7, 11]. Evidence from a mixed-methods approach suggests that adults with obesity often report engaging in PA solely as part of a weight loss goal [12]. This focus on weight loss can be an issue, as individuals may become discouraged and lose interest in being active if they do not see the desired weight loss. Because PA offers health benefits regardless of weight loss, it is important to develop and evaluate a PA-promoting intervention specifically designed for adults with obesity. However, recent reviews found that many online interventions for adults with obesity primarily incorporated general PA recommendations into online interventions focused on diet [13, 14], while overlooking unique PA barriers such as weight perception and engaging in PA solely to lose weight [12, 15, 16].
Based on the literature on PA domains in adults with obesity [12, 15,16,17,18,19,20,21,22,23,24,25,26,27,28,29], we have proposed the development and evaluation of a new online behavioral intervention, Confident Moves (CM) [30]. This intervention is designed to promote PA in adults with obesity by offering learning experiences that enhance their confidence, knowledge, and behavioral skills for engaging in PA. The CM intervention is: (a) grounded in self-efficacy theory; (b) tailored to adults with obesity; (c) designed to promote multiple domains of PA (i.e., job-, transport-, domestic-, and leisure-related PA); (d) developed to be scalable and sustainable through online delivery; (e) evaluated using research-grade accelerometer assessments of PA; and (f) designed to collaborate with a clinical obesity care center or community partner to integrate into comprehensive obesity care alongside diet, medication, and/or surgery. The CM intervention was informed by the Fun For Wellness intervention [31,32,33]. Unlike the Fun For Wellness, which targets both well-being and PA in general adult populations, CM is focused on promoting PA among adults with obesity to facilitate substantial PA change.
In the CM conceptual framework (see Fig. 1), self-efficacy is identified as a key psychological mechanism influencing PA. Self-efficacy refers to individuals’ beliefs in their ability to carry out various levels of performance in the face of specific situational demands [34,35,36]. There is substantial evidence supporting the importance of targeting self-efficacy as a modifiable factor in PA interventions [37,38,