Promoting adherence to weight-related behaviors in young adults: Design of the Nudge microrandomized trial

Just-in-time adaptive interventions (JITAIs) may improve multiple weight-related behaviors by providing highly adaptive, tailored messages. However, evidence regarding what types of JITAI messages are efficacious and under what conditions is limited. We describe the rationale and design of the Nudge microrandomized trial to optimize JITAI messages that deliver distinct behavior change techniques (i.e., BCT messages) and promote daily achievement of weight-related behavioral goals among young adults.

Young adults with overweight or obesity (n = 201) will receive a 6-month behavioral weight loss intervention using our Nudge mobile app, which integrates self-monitoring data from smart scales, activity trackers, and a food log for tracking "red" (high-calorie) foods, and includes weekly lessons, tailored feedback, and daily BCT messages. Participants will have three daily weight-related behavioral goals: weigh daily, meet an active minutes goal, and stay at/under a red food limit. At three daily decision points, participants will be microrandomized to receive or not receive one of seven BCT messages. We will test the effects of BCT messages on daily proximal outcomes: weighing (assessed by smart scale), meeting an active minutes goal (assessed by activity tracker), and staying at/under a red food limit (assessed by food log). Weight will be assessed at 0, 3, and 6 months.

This study evaluates the effects of just-in-time BCT messages on multiple weight-related behaviors. Findings will expand our understanding of what BCT messages are efficacious, when they are efficacious, and for whom, and also guide how BCT messages are integrated into future JITAIs for weight loss.

gov Identifier:NCT05625061https://clinicaltrials.gov/study/NCT05625061.