Neurobiological Underpinnings of Obesity and Addiction: A Focus on Binge Eating Disorder and Implications for Treatment

Abstract

Obesity has been considered within an addiction framework with the term “food addiction” debated as a potential clinical entity. Certain core addiction characteristics, such as diminished control or loss of control while eating, food cravings, and continued behaviors despite negative consequences, appear pertinent to some patterns of disordered eating. Systematic investigations into neurobiological mechanisms underlying these features are ongoing in an effort to understand potential contributions to different patterns of overeating. It is likely that obesity is the result of multiple factors. Genetics, environment, various overeating behaviors (from excess snacking to overeating of nutrition-poor but calorie-dense foods to binge eating), insufficient lifestyle physical activity, and various metabolic conditions may all contribute in complex ways to obesity.

A central research goal is to define how different etiologies and pathways contribute to the many manifestations of overeating and obesity. Discussing obesity as a unitary disorder may obfuscate research findings that pertain to this complex problem; therefore, our focus is on binge eating disorder (BED).

The notion of food addiction has recently been applied to BED, which is defined by recurrent episodes of consuming unusually large amounts of food. It is important to note that persons with BED experience a subjective sense of loss of control during these episodes, but they do not perform the extreme weight compensatory behaviors that characterize bulimia nervosa. BED is the most prevalent eating disorder; it affects approximately 4% of the US population, occurs across all weight categories, and is strongly associated with severe obesity.^1,2 It is linked with increased risk of psychiatric and medical comorbidities. Moreover, BED exhibits behavioral and psychological dimensions that are distinct from other eating disorders.

Although BED is currently categorized as an eating disorder in DSM-5, distinct parallels are noted in phenomenological/behavioral features between BED and addiction. Recurrent binging episodes, a lack of control, and personal distress/negative social consequences appear as core characteristics across both disorders. Understanding the neural systems underlying these features is particularly important because they contribute significantly to appetite regulation, weight, and treatment response.

Despite the prevalence and clinical impact of BED, functional and structural neuroanatomical studies specifically examining BED are only beginning to emerge. These neuroimaging studies are fundamental for demonstrating structural and functional brain characteristics supporting BED as a condition distinct from other forms of obesity or other forms of disordered eating (eg, anorexia nervosa, bulimia nervosa). In addition, these studies clarify the clinical relevance of specific features.