Microbiota and obesity: Where are we now?

Genetic and environmental factors are underlying causes of obesity and other metabolic diseases, so it is therefore difficult to find suitable and effective medical treatments. However, without a doubt, the gut microbiota--and also the bacteria present in the oral cavity--act as key factors in the development of these pathologies, yet the mechanisms have not been fully described. Certainly, a more detailed knowledge of the structure of the microbiota--composition, intra-and inter-species relationships, metabolic functions--could be of great help in counteracting the onset of obesity. Identifying key bacterial species will allow us to create a database of "healthy" bacteria, making it possible to manipulate the bacterial community according to metabolic and clinical needs. Targeting gut microbiota in clinical care as treatment for obesity and health-related complications--even just for weight loss has become a real possibility. In this topical review we provide an overview of the role of the microbiota on host energy homeostasis and obesity-related metabolic diseases, therefore addressing the therapeutic potential of novel and existing strategies (impact of nutrition/dietary modulation, and fecal microbiota transplantation) in the treatment of metabolic disease.