Exercise Extends Life As Much As Caloric Restriction
If you are looking to extend your life expectancy then your most effective option is still to eat 20 percent fewer calories than you really need for the rest of your life. If you go for lifelong starvation you'll live a few score percent longer than normal. Doesn't sound like much fun though. But there may be an alternative that works just as well.
The hunger method – researchers prefer to call it ‘caloric restriction' – stimulates cells to repair themselves. Studies have shown that lab animals live several tens of percent longer than normal as a result. Life extensionists who use the same method in daily life pay a high price however. Being chronically underfed they are always cold, have difficulty concentrating and lose interest in just about everything – including sex. They go through life like a zombie.
Researchers at the University of Florida posed the question whether you really have to ‘do without' the 20 percent of your caloric needs by eating less. They wondered if it's also possible to burn off those calories. So they set up an experiment with 18 healthy men and women aged between 50 and 60.
Half of the test subjects were put on a diet for a year, during which time they ate 20 percent fewer calories than they needed. [CR] The other half ate normally but increased the amount of physical exercise they did so that they burned the same amount of extra energy as the other subjects went without by eating less.
Before and after the experimental period the researchers measured the concentration of FapyGua, 8-oxoGua, 8-oxoGuo and 8-oxodGuo in the subjects' urine [some of the notation is incorrect in the table below]. These substances are the waste products of guanine, which together with adenine, thymine and cytosine is a building block for our genetic material. The more guanine waste products there are in the urine, the more breakdown of genetic material there is and therefore probably also an increase in the rate of aging.
Caloric restriction and increased calorie burning both reduce the concentration of the waste products.
In addition, the researchers extracted RNA and DNA material out of the subjects' white blood cells and counted the number of damaged building blocks in these. From this they discovered that exercise actually worked a bit better than eating less.
"Energy deficits created through both CR and EX reduce DNA and RNA damage to WBC, potentially by reducing systemic oxidative stress", the researchers conclude.
Rejuvenation Res. 2008 Aug;11(4):793-9.