I am not all that comfortable with the developing idea that man can somehow mess around with our genes to increase longevity. I suggest looking outside the labs of our modern Frankensteins at nature and healthy living.
While it is true that numerous studies have demonstrated that caloric restriction is a key to living longer, I also suggest that what calories we take in and which ones we don't are equally, if not more, important. Look for example at the nutrient-dense diet of some of the longest lived peoples on earth in the Mediterranean region - where you also find quite a proportion of pretty rotund people. Clearly much of their health and longevity does not come from caloric restrictions alone.