Scientists have suspected that caloric restriction slows metabolism and as a result, the aging process. One of the mechanisms behind this revelation appears to be that stress causes compensatory increased energy output in the mitochondria of cells which protects them from breakdown so that degradation or "aging" which is associated with heightened levels of cell death coupled with a drop in the rate of replenishment is retarded or slowed down. Harvard and Cornell researchers have isolated this phenomenon to action of 2 genes: SIRT 3 and 4, which suggests that the process might be manageable in the future.
Experiments with animals have resulted in a 25-30% increase in lifespan. However, it is unknown if this will be as effective with humans. At today's average life expectancy of 77.9 in the U.S. (not in the world's Top 10), a corresponding increase would translate into an average of 97 years (minimum) to 101.2 years (maximum).
Your chance of getting Alzheimer's at this point approaches 67% - so that lifespan increases must be coupled with cognitive training and other enhancement programs. Something to remember is that exercise can also accelerate mitochondrial activity associated with delayed aging.