Cells isolated from elderly subjects with or without obesity were significantly impaired in their capacity to differentiate into adipocytes, as revealed by Oil Red O staining of neutral lipids (Figure 1e) and by the gene expression of common adipogenic markers (PPARG, FABP4, LPL, PLIN1, and FASN) (Figure 1f). Here, FASN is linked to obesity due to melanocortin 4 receptor deficiency.