Causes of Rumination Syndrome
The cause of rumination is unknown. Because it is a functional GI disorder, rumination is not caused by an infection or by inflammation.

In some children, rumination occurs at times of significant stress, as a manifestation of rejection, or in children who have previously suffered a more serious eating disorder such as bulimia nervosa. In some cases, stressful life events can be identified around the time of symptom onset, but the disturbance persists even after the precipitating event has been resolved.

However, in most cases rumination occurs in the absence of such identifiable factors. Rarely do people use rumination for "gain," (e.g., to control body weight).