Eating disorder animal model Purpose of review The aim of this review is to describe animal models that simulate the features of eating disorders. The literature pertaining to animal models that are of relevance for clinical eating disorders and the possible underpinning mechanisms was reviewed using PubMed, Ovid database and Google Scholar. Recent findings New refinements of the circuits regulated by neurotransmitters and neuropeptides which instigate eating behaviours and the various feedback pathways which monitor acute and chronic nutrient status continue to be discovered. Moreover, work with the animal models that simulate the behavioural features and risk factors related to eating disorders is flourishing and providing new insights into possible causal mechanisms. For example, rodents develop binge-eating behaviours if they are intermittently exposed to processed, palatable foods and/or sugar adulterated drinks. This led to the controversial conceptualization of binge eating as a form of food addiction. Self-starvation taken to a fatal consequence such as occurs in anorexia nervosa can emerge in rodents exposed to triggers like social exclusion and/or the opportunity to exercise. Summary There are plausible animal models for both anorexia nervosa and binge-eating disorders. These can be used to elaborate the theoretical models to explain the mechanisms underpinning eating disorders.

Neuroimaging and eating disorders Purpose of review Eating disorders are severe psychiatric disorders with a suspected complex biopsychosocial cause. The purpose of this review is to synthesize the recent literature on brain imaging in eating disorders. Recent findings Food restriction as well as binge eating and purging behaviors are associated with lower regional brain volumes or cortical thickness, but those changes largely return to normal with normalization of weight and eating behavior. Computational modeling has started to identify patterns of structural and functional imaging data that classify eating disorder subtypes, which could be used in the future, diagnostically and to better understand disorder-specific psychopathology. The prediction error model, a computational approach to assess dopamine-related brain reward function, helped support a brain-based model for anorexia nervosa. In that model, the conscious motivation to restrict conflicts with body signals that stimulate eating. This conflict causes anxiety and drives a vicious cycle of food restriction. Summary Novel brain research supports the notion that eating disorders have distinct neurobiological underpinnings. This new knowledge can be used to describe disease models to patients and develop novel treatments.

Gonadal hormone contributions to individual differences in eating disorder risk Purpose of review Females experience eating disorders at substantially higher rates than males. Although sociocultural factors have traditionally been thought to underlie this sex disparity, accumulating evidence implicates differential exposure to gonadal hormones early in life. Gonadal hormones also impact within-sex variability in disordered eating, helping to explain why not all women develop an eating disorder, and some men do. We review recent findings regarding these gonadal hormone effects and their implications for the etiology of eating disorders. Recent findings Males are exposed to significantly higher testosterone levels than females perinatally, and this exposure appears to protect against later binge eating in males relative to females. Within-sex, higher estradiol levels among females and higher testosterone levels among males appear to be protective. Progesterone exhibits minimal direct phenotypic effects on disordered eating but appears to counteract the protective effects of estrogen in adult females. Importantly, gonadal hormone effects may be moderated by psychosocial factors. Summary Evidence suggests that gonadal hormones play a critical role in the etiology of disordered eating. Overall, higher testosterone and estrogen appear to be protective across development. Additional research is needed to identify mechanisms underlying these effects and further explore interactions between hormonal and psychosocial risk.

The promise of neurobiological research in anorexia nervosa Purpose of review This article reviews new research in the context of existing literature to identify approaches that will advance understanding of the persistence of anorexia nervosa. Recent findings Neuroscience research in anorexia nervosa has yielded disparate findings: no definitive neural mechanism underlying illness vulnerability or persistence has been identified and no clear neural target for intervention has emerged. Recent advances using structural and functional neuroimaging research, as well as new techniques for applying and combining these approaches, have led to a refined understanding of changes in neural architecture among individuals who are acutely ill, have undergone renourishment, or are in recovery/remission. In particular, advances have come from the incorporation of computational and translational approaches, as well as efforts to link experimental paradigms with illness-relevant behavior. Recent findings converge to suggest abnormalities in systems involved in reward learning and processing among individuals with anorexia nervosa. Summary Anorexia nervosa is associated with neurobiological abnormalities. Aberrant learning and reward processing may contribute to the persistence of illness. To better utilize new techniques to understand the neural mechanisms of persistent anorexia nervosa, it may help to distinguish stages of illness and to link neurobiology with maladaptive behavior.

Treatment delivery strategies for eating disorders Purpose of review The traditional model of treatment delivery, based on a psychotherapeutic intervention delivered by a trained professional, in a one-to-one relationship, occurring in a treatment setting context (e.g., clinic, private office, and hospital), highly restricts access to the best standards of care to all of those in need. In this article, we will be focusing on treatment delivering methods for eating disorders that depart from the traditional mode of delivery. We will focus on the use of self-help strategies, both in a pure self-help format, and with external minimal support, guided self-help. We will additionally review the evidence on the use of internet and mobile technology (m-Health) for delivering treatment. Recent findings Internet-based self-help interventions based on cognitive behavioral approaches have shown to be superior to no treatment for patients diagnosed with bulimia nervosa, binge eating disorder, and other specified feeding or eating disorders with binge/purge characteristics. Although face-to-face, traditional, interventions seem to be more effective than internet-based ones, the latter might have cost benefits and constitute a viable first line of treatment in a stepped care model, or as an alternative to a waitlist while treatment is not available. Other forms of mobile health (e.g., mobile apps) have experienced a surge but remain under researched. Summary Mobile health and the internet are promising media for delivering eating disorder treatment. However, more research is needed to determine the utility of internet-based treatments by comparing them to traditional face-to-face treatments for eating disorders, and explore the moderators and mediators impacting adherence and outcome.

Disordered eating after bariatric surgery: clinical aspects, impact on outcomes, and intervention strategies Purpose of review Disordered eating behaviors (DEBs) are associated with poor weight outcomes following bariatric surgery. We describe DEBs most relevant to this population, their associations with weight outcomes, and emerging data on interventions for DEBs. Recent findings Loss of control eating episodes and grazing have been the most well studied DEBs in bariatric samples. Although DEBs often remit after surgery even without targeted intervention, a subgroup of patients have persistent or newly developed DEBs postoperatively. Preoperative DEBs have little effect on weight outcomes, whereas preoperative impulse control-related features commonly associated with DEBs (e.g., inhibitory control) may have stronger predictive value. Postoperatively, DEBs appear to exert robust effects on concurrently measured weight. Postoperative interventions hold promise for optimizing treatment outcomes. Summary We recommend the following to improve clinical care and move research forward: a common language for DEB constructs is needed to improve cross-talk among researchers and care providers; diagnostic schemes and assessment tools may require tailoring for the bariatric population; mechanisms underlying improvements in DEBs following surgery should be clarified; ongoing monitoring of DEBs in the postoperative period is warranted; and a stepped-care approach may improve weight outcomes in a cost-effective manner.

Eating disorders and posttraumatic stress disorder Purpose of review Childhood maltreatment is associated with all types of eating disorders. We provide a systematic review of the recent literature on comorbid posttraumatic stress disorder (PTSD) in patients with eating disorders, and focus on prevalence, relationship with symptom severity, operating mechanisms and treatment. Recent findings The prevalence of comorbid PTSD in patients with eating disorders ranges from 9 to 24%, with research suggesting that comorbid PTSD is associated with more severe eating disorder symptoms. Maladaptive emotional regulation strategies may mediate the relationship between PTSD and eating disorders. Two pilot studies provide preliminary evidence that concurrent cognitive behavior therapy (CBT) for PTSD and eating disorders may be beneficial and that repetitive transcranial magnetic stimulation (rTMS) could be helpful in the treatment of PTSD in some eating disorder patients. Summary PTSD is a common comorbidity in patients with eating disorders and impacts the severity of their eating disorder symptoms. However, there is little research into concurrent treatments for PTSD and eating disorders. Difficulties in emotional regulation may be a common mechanism in both disorders.

Purging disorder: recent advances and future challenges Purpose of review The present review aims to help specialists remain up-to-date on research from the past 2 years on epidemiology, risk factors, biological correlates, treatment, and outcomes for purging disorder, a DSM-5 other specified feeding and eating disorder. Recent findings Purging disorder affects 2.5–4.8% of adolescent females in population-based samples, but purging disorder remains relatively rare in treatment settings. Higher premorbid body mass index, body dissatisfaction, and dieting prospectively predict purging disorder onset. In studies of biological correlates, women with purging disorder demonstrated significantly greater postprandial increases in the satiety peptide, peptide tyrosine tyrosine, compared to women with bulimia nervosa and controls, and these differences predicted greater gastrointestinal distress in purging disorder. Less than half of those with purging disorder are free from an eating disorder at the end of treatment and at one or more years of follow-up, supporting the need for improved interventions. Summary Purging disorder may occupy a space that falls between anorexia and bulimia nervosa, making it ‘not quite’ anorexia and ‘not quite’ bulimia and difficult to reliably distinguish from each. Improved recognition and understanding of purging disorder requires more research specifically designed to test models of risk and maintenance factors to advance interventions for those who purge without binge eating.