A link between mitochondrial dysfunction and obesity has been proposed [114,115,116,117] based on studies showing that increased visceral adiposity from pre- to postmenopause increases the risk of metabolic diseases [118], and that adipocyte mitochondrial gene expression, including ESR1 (a gene encoding the estrogen receptor α (ERα)), may differ between monozygotic twins discordant for obesity [114]. The gene discussed is ESR1; the disease is obesity disorder.