The gut-brain axis has long been posited as influencing diet choices; however, this has not been well defined in free-living populations, including examination of contributing factors, such as consumption of dietary fiber. This study leveraged baseline data from participants enrolled in a dietary fiber behavioral intervention at the Oklahoma State University Center for Health Sciences. Data utilized were fecal samples for gut microbiome data, three-day dietary recall records for dietary fiber (grams/day), and a stop signal task to identify a measure of impulsivity.