Actually Sucky is right here. The only thing that has been proven to improve longevity is a severe calorie restricted diet. I'm not exactly sure why and there has been much speculation (the last time I checked which was years ago) but it did have something to do with with enzymes and DNA repair. Also, activating some "survival" gene due to the low calories. I also remember something about insulin being an aging hormone and the less you make use of it the better.
First I want to apologize to suckmymuscle for being so condescending. I'm not doubting that CR could be a factor in longevity. It certainly could. Years ago I was posting studies on here about the same thing. But there are other mitigating factors to take into consideration. Quite a few studies that I have read did not take into consideration things like exercise and certain foods that could actually prolong life besides just CR. Losing muscle mass has to be taken into consideration as well. There hasn't really been any conclusion on whether CR is a definite factor in increasing life. Genetics play more of a roll than anything but besides that, there have also been studies that have shown that even if you do not reduce your calories you can replace those calories with more quality foods that will help block certain cells (cancer) and in return possibly prolong life.
There are also some studies that show CR inhibits oxydative to lipids, DNA and protein and has a role in antioxydation. But again, what is CR? What the proper amount to cut? You kinda have to make an educated guess for yourself and weigh out whats better. For me, I would keep my calories higher, protein higher and reduce carb intake and maintain muscle mass at a natural level. It simply doesn't make sense to restrict calories and run the risk of not maintaining muscle mass which is vital for having the transfer of energy (metabolism) run more efficiently. IMO, you put this along with exercise together and you just may prolong your life even further. But again, genetics is damn near everything.
With this being said, no one is right and no one is wrong.