Recent research in mice and monkeys has shown that ultra-low calorie diets actually have the effect of increasing the test animal's life span. The results of the tests were so dramatic that one of the researchers has adopted such a diet himself (1,000 to 1,200 calories a day, or about half what the USDA recommends) in an attempt to extend his own life. Subsequent research confirmed this, also noting a loss of energy and lower levels of activity in the test animals.
Is this the path to extended life? Eating just enough to maintain a state of constant lethargy? It reminds me of an old saying that I heard once regarding good, clean living: "You won't live longer, it will just feel like it."