Rumination disorder (RD; also known as "rumination syndrome") is a disordered eating behavior characterized by the repeated regurgitation of food during or soon after eating. The frequency of repeated regurgitation of food typically occurs at least a few times per week, frequently daily with subsequent re-chewing, re-swallowing, or spitting out of the regurgitated material. The widely used technique for treatment of RD has typically been diaphragmatic breathing, which works by serving as a competing response to abdominal wall contractions, which is hypothesized to trigger regurgitation. However, the efficacy of diaphragmatic breathing remains unknown and has mainly been delivered through a one-session instruction with an occasional follow-up.