Regarding enzymes, several studies observed significantly higher levels of salivary alpha-amylase (sAA), matrix metalloproteinase-9 (MMP-9), and matrix metalloproteinase-2 (MMP-2) in individuals with obesity, those in the control group [33, 39, 42]. This evidence concerns the gene MMP2 and obesity due to melanocortin 4 receptor deficiency.