The big question about calorie restriction in humans is what effects it may have on mental functioning. I don't know about you, but I have trouble concentrating when I am hungry; and there is the further risk of poor mental development with calorie restriction in children.
Also this is not new (well the drug possibly imitating the effects of calorie restriction is), I read Waldrop's life extension book which concentrated on calorie restriction back in the early 1990s. The concerns about mental functioning were brought up soon after by several critics of the book. I didn't bother looking up the title, etc because I seriously don't recommend it, it was a waste of time, very shallow.
An interesting question would be whether stimulants, like caffeine, can be used to increase brain function without calories. I wouldn't suspect this to be a healthy option though...
Personal experience indicates that they can. In fact, I find that is one of the main problems I have with stimulants - they tend to suppress my appetite, but since I am still able to function well on them I don't notice how hungry I am until they wear off and I crash becasue I haven't eaten in 3 hours.
Don't you notice the depletion of neurotransmitters? It's been a awhile since I played with nootropics, but my understanding of how many cognitive enhancers work is that they stimulate the production of underlying neurotransmitters (norepinephrine, for example).
If you are not providing the body with sufficient raw material (feeding your head, as it were), these transmitters get depleted and no amount of stimulants will help.
I don't understand the obsession with trying to add a few years to human lifespans. I'd personally rather live a shorter enjoyable life than a long one full of depravation just so I can eek out a few more years at the tail end.
I guess that's easy to say since I'm barely reaching middle age.
For the record, the present consensus amongst aging researchers is that there are strong evolutionary arguments for CR to have an effect of only a few years on human maximum lifespan.
While of course the human studies (go Google "CALERIE", the study name) show that it has a massive positive effect on health and resistance to age-related disease.
Exercise won't necessarily prolong your life, but it will prolong your quality of life. There are 60-year-olds who are helpless and 80-year-olds who are independent and active.
