Anorexia nervosa (AN) is an eating disorder characterized by abnormal low body weight, a decrease in daily caloric intake, and an acute dread of gaining weight. This pathological control of overweight and physical form progressively disrupts patients’ lives. While the origins of AN are not fully understood, several risk factors such as genetic susceptibility, environmental variables, and life adversity have been linked to this disease. Recent findings have identified the anaplastic lymphoma kinase (ALK), a tyrosine kinase receptor, as a key gene in controlling thinness by regulating energy expenditure via hypothalamic sympathetic control. Furthermore, new research has highlighted its possible role in AN, utilizing the rat activity-based anorexia (ABA) model, indicating that ALK might be involved in its stability, resistance, and/or aggravation. This book chapter aims to provide a comprehensive understanding of the state of the art in AN and the role played by the ALK receptor.