In view of the promising results of fecal microbiota transplantation (FMT) in animal models, a double-blind, randomized, clinical trial investigated the effect of FMT in obese individuals with metabolic syndrome, showing an improvement of insulin sensitivity in those participants who received FMT from a lean donor, whereas the control group who received their own microbiota remained at stable insulin sensitivity. This evidence concerns the gene INS and metabolic syndrome.