Obesity is a condition mainly caused by an alteration in energy intake, shifting towards positive energy balance, which can be influenced by genetic and environmental factors. The human gut is heavily populated with microbial organisms. Recent evidence suggests that obesity is influenced by specific bacterial phyla present in the human gut that have increased energy harvesting capabilities. The main objective of this review is to identify the microbial taxa that are related to obesity and weight loss. In this review, we also discuss the differences between the phylum ratio of the gut microbiota population of obese individuals and that of individuals who have healthy weight. It has been shown that obese individuals have a higher ratio of Firmicutes to Bacteroidetes than healthy weight individuals. The few studies to date have shown that weight-loss treatment may change microbial population of the gut, as there is a decrease in the ratio of Firmicutes to Bacteroidetes. Treating imbalances of the gut microbiota may offer new possibilities for treating obesity.
Keywords: Intestinal microbiota; Obesity; Weight-loss.