ABSTRACT
The obesity epidemic shows rapid growth and represents a serious public health crisis. Various complications, including metabolic syndrome, cardiovascular diseases, musculoskeletal disorders, and cancer, are reported in obesity. The gut microbiota consists of abundant microorganisms that form a dynamic ecosystem and can affect host metabolism, immunomodulation, and biosynthesis. In this chapter, we discuss the tridirectional relation between the host physiologic status, diet pattern, and gut microbiota. The diversity and abundance of specific bacteria in the gut become critical dynamic factors that modulate host homeostasis. Additionally, bacterial metabolites mediate host physiology by signaling, stimulation, and inhibition. These bacterial metabolomes, such as short-chain fatty acids and lipopolysaccharide, can interact with host metabolomes and can be detected in host feces, urine, and blood. We also discussed how the gut microbiota implicates host feed behavior and satiety by affecting host metabolites, the vagus nerve, hypothalamus, and brainstem. We further discuss the potential mechanisms. Diet is a crucial factor affecting the gut environment and changes in the composition of the gut microbiota and diversity that influence host metabolism. Scientific evidence supports the idea that an unhealthy diet may lead to microbiome dysbiosis and induce several sequelae. Not only macronutrients but micronutrients are involved in the alteration of the gut microbiota. Currently, scientists are trying to resolve the obesity issue by manipulating the gut microbiota. Fecal microbiota transplantation, probiotics, and prebiotic intervention are considered therapeutics for obesity, metabolic syndrome, and diabetes mellitus. Scientists are dedicated to clarifying the relationship between the gut microbiota and host metabolism. The gained knowledge drives the development of therapies that solve human health problems and enhance well–being.
