Adipose differentiation is a multistep process with the following sequence: adipoblasts --> preadipocytes --> adipocytes. Adipogenic agents are only involved in the terminal differentiation of preadipocytes to adipocytes by means of circulating hormones (growth hormone, glucocorticoids, or triiodothyronine) and locally produced hormones (prostacyclin). Fatty acids also behave as hormones and act as transcriptional regulators of lipid-related genes. Once differentiated, adipocytes become secretory cells able to synthetize and release an impressive number of peptide and nonpeptide compounds, suggesting a potential link between excess of adipose tissue mass and various physiopathphysiologic consequences.