Primary investigations were around “is there a difference in the RBP4/visfatin levels between periodontitis patients with obesity and those without obesity?” To answer this question, subgroup analysis was also first performed based on the population between patients with OP and normal-weight patients with periodontitis (NP) (Figure 2 and Figure 3). This evidence concerns the gene RBP4 and obesity due to melanocortin 4 receptor deficiency.