In recent years, there is great interest in research to investigate the intestinal microbiota in diseases of particular importance for health. This opens for a new area of research in the role of the human intestinal microbial flora in inflammation, pathogenesis of obesity and other associated disorders. Recent studies suggest the association of the intestinal microbiome with the development of obesity and metabolic syndromes such as type 2 diabetes, which is a metabolic disease that is mainly caused by obesity associated insulin resistance. Also, the effects of obesity appear to play a role in the development of Alz-heimer’s disease. In this way, emerging studies are showing that human microbiome may contribute to the regulation of multiple neurochemical and neurometabolic pathways through a complex series of highly interactive and symbiotic systems signaled by the host of the microbiome, which interconnects the gastrointestinal tract, skin, liver and other organs to the central nervous system. Studies conducted both in humans and in mice models have demonstrated the role of the intestinal microbial flora in the pathogenesis of obesity. The possibility that high adiposity increases Alzheimer’s disease risk is alarming given global trends of overweight and obesity in the general population. However, prevention and manipulation of adiposity may also provide a way to prevent Alzheimer’ dis-ease. The purpose of this study is to discuss actual results that may explain the role of mi-crobial flora in the development of obesity and Alzheimer’s disease.