Tracing Triggers of Purging Among Anorexia Nervosa Patients

In a recent study of adult women with anorexia nervosa, binge eating large amounts of food was the strongest predictor of purging, challenging the idea that loss of control is the most powerful aspect of distress in bulimia nervosa and binge-eating disorder. The researchers concluded that both loss of control and overeating appear to be important determinants of purging in patients with AN.

The multi-center study, headed by Andrea B. Goldschmidt, PhD, of the University of Chicago, studied behavioral, emotional, and situational factors linked to purging among 118 women with AN (Int J Eat Disord. 2015; 48:341). The women completed a two-week assessment protocol, including daily self- reports of eating disorder behaviors, mood, and stressful events. Prior to the study, the women spent two days practicing, to increase their familiarity with the protocol. Using a handheld computer, the women recorded their mood, stressful events, and behaviors after every binge-eating episode or AN behaviors such as binge eating and purging.

The women responded to 6 daily semi-random prompts by investigators that occurred every 2 to 3 hours from 8 am to 10 pm. The women also were trained in standard definitions of events by the research staff and; they reported all body checking and purging behaviors. An abbreviated Positive And Negative Affect Schedule-Expanded (PANAS-X) form enabled participants to rate each reaction (such as nervousness or disgust) on a 5-point Likert-like scale, ranging from “Not at all” to “Extremely.” Participants also recorded stressful events that occurred during the time from the last recording.

An unexpected finding

The researchers examined nearly 6,000 eating events from all the recordings, including 367 self-reported binge-eating episodes and 537 loss-of-control episodes, 152 overeating episodes, and 4,584 episodes that involved neither loss of control nor overeating (NE). Negative affect predicted purging after NE. A total of 112 purging episodes (34.5% of all purging episodes) were reported after NE.

The finding that self-reported binge eating most strongly predicted purging did not correlate with the authors’ hypothesis that loss of control would be associated with purging. Prior studies have not included participants with AN, and thus the findings suggest that binge eating may differ among diagnostic eating disorder subgroups. The patient’s subjective perception that she has consumed an “excessive” amount of food may be particularly important in AN, according to the authors.