The correlations between gut microbiota (based on OTUs) and obesity related indexes (including body weight gain, percent of epididymal fat weight, the levels of TG, TC, HDL, LDL, TNF-α, IL-6, IL-10, and IL-4) were investigated using the Pearson correlation analysis. This evidence concerns the gene IL4 and obesity due to melanocortin 4 receptor deficiency.