The Role of Gut Microbiota in the Pathogenesis of Obesity and Food Addiction: The Importance of the Gut–Brain Axis and the Dopaminergic System

Obesity is one of the most serious public health challenges worldwide and has reached the scale of a global epidemic. Its etiology is multifactorial and includes genetic, environmental, hormonal, and neurobiological factors. In recent years, increasing attention has been paid to the role of the gut microbiota in the regulation of energy metabolism, inflammatory processes, and the functioning of the gut–brain axis. An increasing body of evidence suggests that the gut microbiota may influence the dopaminergic system and eating behaviors through bacterial metabolites, immune pathways, and the vagus nerve. Disturbances in microbiota composition may contribute to the development of chronic low-grade inflammation and compulsive consumption of highly processed foods. This article discusses the concept of food addiction as a phenomenon involving loss of control over eating, excessive reward system reactivity, and dopaminergic dysfunction within the mesolimbic reward system. Particular attention is given to the role of the gut microbiota in modulating these processes, including the potential effects of selected commensal bacteria and the importance of dietary interventions such as the ketogenic diet in regulating the gut–brain axis. The presented data suggest that modulation of the gut microbiota may represent a promising supportive strategy in the treatment of obesity and disorders associated with compulsive eating. At the same time, it is emphasized that the current state of knowledge is largely preclinical and observational, highlighting the need for further translational and clinical studies.