Eating patterns in youth with restricting and binge eating/purging type anorexia nervosa.

Anorexia nervosa (AN) is a life-threatening illness characterized by greatly restricted energy intake, fear of weight gain, and body image disturbance.1 The current Diagnostic and Statistical Manual of Mental Disorders (DSM-51) specifies two sub groups of individuals with AN- those who engage in binge eating and purging (i.e., binge eating/purge type; AN-BE/P) and those who do not (i.e., restricting type; AN-R). Previous research has found that patients with AN-BE/P often have higher eating disorder severity, more co-morbidities and worse prognosis than patients with AN-R.2 However, other research has shown minimal differences between the two groups.3 Despite the growing literature looking at AN-R and AN-BE/P, factors related to the development of binge eating and purging in AN remain unclear. Binge eating and purging have been explained via the restraint model,4 which theorizes that dietary restraint leads to binge eating and subsequent purging; this in turn leads to a cycle of increased efforts of restraint. Although this model was originally created to explain binge eating and purging in Bulimia Nervosa (BN) and Binge Eating Disorder (BED),4 irregular eating patterns may contribute to the development and maintenance of binge eating and purging across eating disorder diagnoses, including AN-BE/P. Previous research suggests that women with AN either follow a regular meal and snack pattern (i.e., three meals and three snacks per day) or have irregular eating patterns (i.e. skipping meals/long intervals without eating).5 Other research using computer-based 24-hour dietary recall6 reveals that adults with AN have approximately six eating episodes per day, with fewer eating episodes on purge-only days, and more eating episodes on binge days (with or without purging). Although a few studies have suggested that eating patterns in adults with AN typically involve fixed meal times and stereotyped food choices,7 other studies suggests that this rigid dietary pattern is only one of several eating patterns among those with AN.5 These studies contribute to current knowledge about dietary intake patterns among adults with AN, but there is a gap in understanding whether these patterns generalize to adolescents with AN. Furthermore, little is known about the timing of dietary intake patterns, and which specific meals and/or snacks are most often consumed over the course of the day. Research examining specific meal and snack consumption has focused primarily on individuals with BN and BED.8–9 These studies suggest that individuals who consume meals and snacks with irregular frequency also tend to engage in binge eating. Loss of control (i.e., the sense that one cannot control what or how much one is eating) also seems to play a role in frequency of eating, such that youth with loss of control eating consume fewer meals but more snacks than their peers without loss of control.10 In spite of the growing literature exploring eating patterns and binge or purge behaviors, there has been a lack of research using AN samples. It is unknown whether these relations between eating patterns, loss of control, binge eating, and purging hold true in AN, and to what extent they differ by AN subtype. Understanding the link between irregular eating patterns and binge eating or purging across eating disorders may elucidate a common mechanism that could inform future treatment development. In particular, a better understanding of meal patterns in AN is needed to individually tailor interventions. For example, the focus of one intervention may be to augment portions for patients with AN who are already participating in regular meals, while implementing a regular meal schedule may be more important for patients who are not eating regular meals. The current study expands upon the existing literature by describing eating patterns in youth with AN-R and AN-BE/P, with a specific focus on meal and snack consumption. This study seeks to address two aims: (1) How frequently are meals and snacks consumed by youth with AN-R and AN-BE/P? (2) Is meal and snack consumption frequency associated with binge eating or purging behaviors? It was hypothesized that youth with AN-R would report more regular eating patterns relative to youth with AN-BE/P, and that youth with AN-BE/P who have less regular eating patterns would present with more frequent binge eating and purging episodes. Findings from this study may contribute to our understanding of eating patterns in maintaining binge eating and purging in AN.