The role of SIRT3 as a regulator of cellular metabolism is demonstrated by SIRT3 deficient mice which are more susceptible to the pathological effects of a diet containing excess fat, as they rapidly develop obesity, insulin resistance, hyperlipidemia, and hepatic steatosis following high fat (HF) feeding (Hirschey et al., 2011). The gene discussed is SIRT3; the disease is Obesity.