One metanalysis of six studies with 154 participants assessed the role of FMT in the treatment of obesity and metabolic syndrome, finding a minimum decrease in HbA1c 6 weeks after the intervention that disappeared in the long-term, as well as in our study, without an improvement in anthropometric parameters, glucose levels, or insulin sensitivity compared to placebo [8]. The gene discussed is INS; the disease is obesity due to melanocortin 4 receptor deficiency.