Worthy of note, a secondary outcome of the POLYGIR study is the evaluation of SIRT1 gene expression in SKM and WAT of patients receiving red grape polyphenols or placebo for 8 weeks, confirming the growing scientific interest towards the potential role of sirtuins in the anti-obesity effects of polyphenols. Here, SIRT1 is linked to obesity due to melanocortin 4 receptor deficiency.