The MIT Technology Review gives an overview of research into the genetic and biochemical mechanisms of calorie restriction. "For more than a decade, Guarente has been gradually solving the puzzle with the ambitious goal of discovering how to slow the aging process in humans without imposing a thousand-calorie-a-day diet. In 1999, he came to the surprising conclusion that manipulating just one gene, SIR2, could affect longevity." There is competition these days in the field of calorie restriction mimetic drugs - we are probably only a few years away from commercial products that will make a lot of money for whoever develops them. "It's a race now ... both have very big labs working hard. They both have companies working hard, too."
Link: http://www.technologyreview.com/articles/04/10/scanlon1004.asp?p=0