The overarching goal of our proposed project is to develop an efficacious standalone text messaging obesity intervention. We focus on standalone approaches -- treatments that can be wholly delivered via text messaging -- because of their dissemination potential. Standalone treatments are readily scalable, can be used modularly, and several such interventions (e.g., Text4baby) have achieved population reach. Despite their translational potential, no trials have yet tested a fully standalone texting intervention for weight loss. To accomplish this goal, we propose to use the multiphase optimization strategy (MOST) to identify which intervention components should optimally be included in our standalone texting weight loss intervention. MOST guides the randomized experimentation of intervention components so that we might assemble a treatment package comprised only of components that make a meaningful impact on weight loss. We will conduct a 12-month experimental trial among 592 obese adults. All study participants will receive a core 6-month weight loss texting intervention (based on our iOTA approach) that includes tailored behavior change goals, interactive self-monitoring, automated feedback, and skills training. Using a fractional factorial design, we will randomize participants to one of 16 experimental conditions (37 in each condition) that will test the text messaging components (and levels). We will follow participants at months 1, 3, 6, and 12. We will experimentally determine which text messaging components (and component levels) produce a meaningful contribution to 6- month weight change and 6-month change in diet, physical activity, and the proportion of participants who achieve > 5% weight loss at 6 months and maintenance at 12 months. We will examine associations of engagement and non-usage attrition with weight change, model trajectories of change in engagement and non- usage attrition over time, and test theoretically-driven mediators of engagement, self-efficacy, and the Technology Acceptance Model constructs: perceived ease of use and perceived usefulness. We will also determine the cost of the intervention?s implementation and its incremental cost effectiveness. Finally, we explore whether combinations of intervention component are differentially efficacious by participant characteristics; this will allow us to ultimately tailor intervention structures for optimal outcomes. This study will demonstrate how to best assemble a low cost, high reach standalone texting weight loss intervention.
We propose to identify the most effective way to build a completely standalone, text messaging-based weight loss intervention. Thus far, no standalone texting treatments have proved successful. Our proposal is significant for several reasons. For the public, an effective standalone texting intervention for weight loss would have major impact. It could be a first-line offering -- broadly accessible by individuals, communities, health care providers, and other stakeholders who want to quickly and inexpensively engage a high quality, evidence- based obesity treatment. For the field, this proposal will do several things. It will be the first to use MOST to optimize an mHealth intervention. Our trial will result in an optimized texting treatment package. We will also determine whether the package varies for different subgroups ? ultimately allowing us to better personalize intervention content. In short, our proposed study will help create a greatly needed obesity treatment strategy, while guiding the field towards a new approach for developing more effective mHealth interventions.