Fiber for improvement of behavior, eating, and risk: Protocol for a randomized controlled trial examining a behavioral intervention focused on facilitating improved dietary fiber consumption, eating behavior, and cardiometabolic risk in adults with obesity.

Background: Despite a long-standing appreciation for the benefits of dietary fiber consumption, there is a lack of interventions focused exclusively on improving dietary fiber intake. Aim: The aim of this study is to determine the effects of an intervention focused singularly on improving dietary fiber on weight, eating behavior, and markers of cardiometabolic risk. Methods: This pilot study will employ a three-arm, factorial design to examine effects of a novel dietary fiber-focused intervention: Fiber for Improvement of Behavior, Eating, and Risk (FIBER), compared to standard weight loss education alone or in combination with FIBER. FIBER is 3 months long, including group-based educational sessions and remote counseling using motivational interviewing. Intervention content is focused on dietary fiber. This includes what dietary fiber is, where to find it, why to consume it, and how to consume it via theory-driven behavior change techniques and strategies (e.g. observational learning). Adults consuming ≤25 g of dietary fiber/day and a body mass index ≥30 kg/m² will be recruited using online advertisements. Participants will complete in-person data collection visits at baseline and 1 and 2 years post-FIBER to measure body mass (primary outcome), blood lipids, dietary fiber intake, behavior and cognitive measures, stool samples, and body composition (secondary outcomes). One remote data collection session will occur directly after FIBER to assess dietary fiber intake and behavior and cognitive measures. Summary: This study will provide data regarding effects of a dietary fiber-focused intervention on diet and eating-related behavior, body weight, and cardiometabolic risk factors in adults with obesity.