Evidence on the role of gut microbes in obesity

Abstract

Obesity results from a positive energy imbalance and it is associated with a chronic low-grade inflammation. The microbiota that populates the gut is considered a novel factor that, together with lifestyle, may be involved in obesity. On the one hand, the gut microbiota is globally involved in energy metabolism by improving the host's ability to extract and store energy from the diet. On the other, the commensal microbiota regulates immune functions, protecting the host from infections and chronic inflammation. Saturated lipids and Gram-negative bacteria trigger similar proinflammatory responses through their recognition by the same receptors of innate immune cells and adipocytes, associated with obesity and insulin resistance. Metabolic endotoxaemia is also a possible inflammatory factor causative of insulin resistance development and weight gain in animal models. In contrast, the administration of certain prebiotics may reverse this process and restore the gut balance. The gut colonization process and the administration of certain probiotics and prebiotic substrates have also been related to the production of neuroendocrine secretions involved in the short-term and long-term food intake control. The future progress in the identification of the different roles played by specific gut bacteria in body weight regulation could contribute to the understanding of obesity etiology and the design of additional intervention strategies to control this and its associated disorders.