ESPE Abstracts

The obesity pandemic is likely multifactorial, comprised primarily of reduced caloric expenditure and increased caloric intake secondary to dietary changes, coupled with host genetic predisposition and other environmental exposures. The role of the host microbiome in metabolism, energy expenditure, and metabolic disorders, including obesity, has more recently come under scrutiny as well. For example, several perturbations in the host microbiome have been associated with obesity. The multitude of bacteria that comprise the human gut microbiome can interact with host metabolism and promote obesity through several pathways. Firstly, the gut microbiome can digest dietary components that otherwise would not provide significant caloric intake for the host, potentially increasing caloric absorption by up to 10 percent. One classic example of this is the digestion of dietary fibers by gut bacteria, with conversion to short-chain fatty acids. Secondly, the microbiome interacts closely with the host intestinal innate immune system, which may also modulate host metabolism. Such regulation and increase or decrease metabolic demands, while also modifying distances for nutrient diffusion dependent on the degree of inflammation present. Several factors can also modify the host microbiome, indirectly affecting the host metabolism and promoting weight gain. This is classically described in the agricultural industry, where antibiotics have been exploited for decades to promote weight gain among various livestock. More recently, several murine and human epidemiologic studies have suggested a similar role for antibiotic exposure early in life and pediatric-onset obesity. Lastly, there are multiple active studies assessing how we might be able to modify a person's bacterial composition in order to advantageously affect their metabolic derangements.