The discovery that Sir2p requires NAD for its activity immediately suggested a link between SIR2 activity and caloric restriction. This link was strengthened by the observation that life span extension by caloric restriction requires Sir2 protein. Caloric restriction is likely to reduce the carbon flow through glycolysis and result in more free cytoplasmic NAD. SIR2 could act as a sensor of NAD levels within the nucleus. Under conditions of caloric restriction, NAD levels are high, SIR2 is activated, and the rate of aging is decreased.
Scientists are in the middle of a good old fashioned research story here - the outcome is likely to have a strong positive impact on our future health and longevity. In the meanwhile, you should certainly investigate calorie restriction if you haven't already done so.