CR inhibits mTOR (mTOR1, I think), and, likely through mTOR, increases the production of mitochondria. Increasing the number of mitochondria in a cell, all else being equal, reduces the voltage across each individual mitochondrial membrane, and thus reduces the amount of reactive oxygen species predicted, and thus the rate of mitochondrial DNA damage. Mitochondrial DNA damage reduces ATP production, reducing the ability of the cell to do its work, and also to produce protein for its own upkeep; and may also lead to apoptosis.
This is a brief summary, but there's lots of evidence IMHO that either mitochondrial proliferation, or else the general downregulation of anabolism, is responsible for the effects of CR.
I note that that first theory doesn't even get mentioned on:
http://en.wikipedia.org/wiki/Calorie_restriction#Mechanism_of_Action
Life extension is a relevant topic here, and I was wondering if people are aware of the apparently life-extending effects of calorie restriction (CR) and intermittent fasting (IF). To the extent of my knowledge, this is the best method using currently realized technology that has shown repeated and significant life-extension benefits.
Studies show that reducing calories by 20% to 40% from ad libitum feeding (but maintaining the supply of required protein and micro-nutrients) gives improvements in markers related to aging, and extends life span in rodents and other organisms.
Other rodent studies have also shown similar results in subjects which were kept on various intermittent fasting schedules. Rats that were fed only on alternating days gained up to 25% lifespan (see Table 2).
The benefits of IF are seen even if the total calorie intake is the same as in ad libitum subjects.
There are ongoing full-lifespan studies in rhesus macaques to test the effects in primates, but none of these studies have completed. This abstract of the interim results appears promising, though.
Studies of CR and IF on humans have shown effects consistent with reduced mortality, including:
- Improved triglyceride profiles (a marker for heart disease)
- Increased insulin sensitivity
- Reduced cell proliferation (a marker for cancer)
Generally, these diet modifications appear to not just extend life span, but improve the quality of life too. In aged subjects they improve things like: muscle mass, cognition, energy, appearance, and activity level.
Have people heard about this or tried it? If you are trying to maximize your chance of surviving to the point that technology can lengthen lifespan indefinitely, it seems like something worth exploring.
I tried an IF schedule for about 6 months during 2010. I followed a schedule of 3 x ~thirty hour fasts every 7 days and found it somewhat tolerable. I exercise regularly and found that exercising on the non-fasting days was not a problem. I'm thinking of starting up such a schedule again.