The prevalence of obesity is increasing with a huge economic burden. At younger age, obesity can adversely affect almost every organ system and is often associated with hypertension, dyslipidemia, insulin resistance or diabetes. In addition, children are more susceptible to the interaction between genetic and environmental factors, which can substantially increase the risk of chronic diseases in adulthood. Attempts to explain this epidemic have focused on several contributors including calorie intake, changes in diet composition and in the microbiome. Gut “microbiome”, the collection of microorganisms living in our intestines, profoundly impacts many aspects of host physiology, such as metabolism, resistance to infection and regulation of the immune system. Moreover, several lines of investigation indicate that microbiome–host interactions may contribute to a broad range of extraintestinal inflammatory diseases and alteration of metabolic pathways. Here, we intend to study the impact of various diets on microbiome and their correlation with inflammation and metabolism. Thus, this study may help to develop new guidelines for feeding at younger ages and to improve health outcomes.