The Role of the Gut Microbiome in Obesity

Abstract

The human gut contains complex assemblies of trillions of microorganisms with a collective genome termed the microbiome. This “other” genome consists of several million genes as compared to the about 23,000 genes in the human nuclear genome, and in contrast to the human genome, the gut microbiome is constantly changing and under influence of environmental factors and likely also individual variations in the human genome. In this chapter, we discuss the nature of the link between the gut microbes and obesity with a main focus on human studies. Whereas current evidence consistently suggests that alterations in the gut microbiota associate with many of the complex metabolic disturbances of obesity, causality is not yet substantiated. Improvement of our understanding of the link between gut microbes and obesity will involve future integrative approaches using genomics, metagenomics, metabolomics, and interventions to elucidate associations between our human genome and the microbiome as well as the metabolic associations between the gut microbes and the host. Thus, it is yet premature to conclude whether imbalances in the composition and function of the gut microbiota represent a new therapeutic target in prevention and treatment of obesity and its comorbidities.