I have been doing some research on caloric restriction, and have been surprised by what I have found.  I'm sure you have all heard of the concept, but if you haven't I'll give a brief outline:

CR is, in essence, just lowering the amount of calories in daily diets.  There is no magic number of calories that should be consumed per day, thus there is no magic number on how many calories should be consumed when calorically restricted.  However, some scientists who have been testing CR have set the bar at 60% of the calories of an animals typical daily diet.  It has been proven that these animals live longer.  They have a far lower cancer and cardiovascular disease rate.  If CR is started at birth, these animals grow to be much smaller than non CR animals of the same species.  They do, however, have the same level of function.  Most importantly, a significant increase in lifespan was noted in each animal. CR rats increased their average lifespan by over 100%.

There are many hypotheses on why CR is so successful, and the most commonly accepted one at the moment is that of SIRT1.  SIRT1 is in all cells, and it regulates DNA replication.  During average aging, SIRT1 is downregulated, and instances of DNA mutation increase substantially.  Increased DNA mutation=increased chance of disease.  In CR, through various mechanisms that, to be brutally honest I don't feel like explaining, SIRT1 is not downregulated.  SIRT1 being active leads to decreased free radicals, and an increased lifespan.

Side note: there is a big push for people to start taking resveratrol. Resveratrol is the reason people say drinking red wine is beneficial to you.  It decreases the amount of free radicals (perhaps the number 1 reason for disease).  It acts as basically as SIRT1. Early tests have shown that a small amount of resveratrol can increase lifespan, so manufacturors have jumped at the chance and began selling resveratrol in pill form.  Many consumers have bought it because it is being dubbed a "longevity" supplement.  However, the pills the sell have an obscene amount of resveratrol in them (i.e. the amount in 200 glasses of red wine).  It has also been shown that cancer cells cannot spread without SIRT1, or resveratrol (if you want to me explain this mechanism as well I can, I am just kind of pressed for time).  So, in animals taking resveratrol, a highly accelerated spreading of cancer can (and usually does) occur.  Read: Do NOT take resveratrol.  Tests have not been completed, but since it is a natural supplement, companies are allowed to sell the product anyway.

Ok, so back to CR.  The longwinded explanation above leads me to my question:  Do you think CR is feasible in humans?

IMO, I don't think so.  Food, and thus eating, is the main component to socializing in humans.  Every party any of us have ever gone to has had some sort of food or beverage.  Dates are for 'a bite to eat', birthday parties have cake, someone from work bought a dozen bagels, etc.  We are inundated with food on a daily basis, and I think that for CR restriction to work on humans, we would have to change our entire social order.

CR, again in my opinion, is the proverbial fountain of youth we have been looking for, but I just don't think it is something that can be effective in humans, but we may soon have some 45 year old dogs!