While stated as sarcasm, this is a very reasonable concern.

Suppose we can extend human life with Calore Restriction, but at the cost of having to slow person's activity to the point that the overall amout of actions (work, leisure etc.) remains the same as during shorter, more intense life.

Would that still be worth it? What would a person gain through longer lifespan if she was limited to roughly the same amout of activity anyway? Wouldn't competing people gain advantage simply by being able to take advantage of opportunities quicker?

I've dabbled with caloric restriction before for brief periods of time. I found that my body adjusted pretty quickly to it in a metabolic sense and the only real issue (and the reason I dabbled but never became a real adherent) was appetite, which I suspect will eventually be solvable via pharmacological means.

Intermittent caloric restriction is also showing promise. You don't have to starve yourself daily -- just a couple of times a week -- to show some of the same benefits. Perhaps not to the same degree, but far more comfortably.

Why speculate when we already have some data on activity levels under CR?

http://en.wikipedia.org/wiki/Calorie_restriction#Activity_le...

Very interesting!

>Laboratory rodents placed on a CR diet tend to exhibit increased activity levels (particularly when provided with exercise equipment) at feeding time. Monkeys undergoing CR also appear more restless immediately before and after meals.[62] Despite this brief daily period of increased activity overall activity is no higher in CR than AL animals in youth after an initial period of adaptation to the diet.[63] On the other hand, CR has been found to retard the decline in activity that occurs during normal aging: in one study, animals on a conventional diet "showed little activity" by early middle age, while those on CR "were observed to run around the cage and climb onto and hang from the wire cage tops throughout their life spans. In fact, the longest surviving [CR] mouse was observed hanging from the top of his cage only 3 days before he became moribund."

Just thinking all futurism here, but it could be useful in the case where we don't need as much physical activity but rely more on thinking, or if we have things pretty automated and just need to wait for things that take a long time.

To add another perspective to this. If we assume that after a period of adaption eating less is just as much of a joy as eating a bit too much from time to time, there are still other factors.

Most of them are a product of vanity, but they still shape our culture.

How would I look if I reduce calories? I would lose a substantial amount of muscle mass. I would be weaker. I could not recover from endurance and strength work as fast as I'm used to.

If we throw all reasonable studies into a bucket and have them guide our lives, what would happen?

I wouldn't be tan. I wouldn't grow as large because small people supposedly live longer (though this is of course not something we can influence yet). I would have a very low muscle tonus as well as mass and only sufficient muscular endurance and size to do whatever I have to do (which is very little compared to a blacksmith in 1407). I would share a grey substance (heck, let's keep the name soylent) with my date that has everything I need to live. I have no car to reduce my carbon footprint. I will avoid the sun in general due to my skin color which is very prone to cancer (thankfully my children will be genetically altered). I will gladly try to avoid talking about any of this because saying "Don't you think beeing vegan is awesome?" will lead to an imaginary bullet flying in my general direction.

Let's have a vote of how many women find this lifestyle that will carry me into my 100s so mind-boggling attractive while I'm still in my 20s.

Everything you describe as attractive qualities you don't want to sacrifice are fashion fads that were once considered unattractive.

The insightful notion that life at 20 is permanent adulthood and the future is irrelevant has been believed by 20somethings for millenia.

Scientist thought they could shortcut this process by discovering the underlying biochemical mechanism. One promising lead was the insulin subsystem which is ubiqitous in our tissues and in most animals for nearly 700 million years. This lead to the SIR family of genes and chemicals like red wine that seem to manipulate them. What works in yeast and worms doesnt seem to apply to mammals that well yet. Western mdicine: develop and take a PILL to solve your problems.

>So if you don't eat much you may live longer. >It will certainly FEEL longer.

https://www.youtube.com/watch?v=h7fs33Jewsg&t=4m25s

According to people that do it they feel great (possibly due to BDNF activation in the brain).

BDNF will affect neuronal proliferation, but won't affect how you feel (mood) in the short term.