If you want to increase your chances of living longer, eat less.

Restricting calorie intake is a reliable way to extend life span. It works in every animal model that has yet been tested. Mice, rats, Guinea pigs, rabbits, dogs and fruit flies all live longer if you feed them less. In humans, this would amount to an additional 25 years of life. Not only do calorie-restricted animals increase life span by about one-third but they also look and behave younger.

The work of Drs. Wolf and Pendergrass at the University of Washington, Seattle, shows that caloric restriction slows the rate of cell division. Remember that, in a cell, age is measured not in elapsed time but in the number of cell divisions. If you slow cell division, you slow aging because fewer cell divisions mean less shortening of telomeres. For a refresher on telomeres see Health Alert 30.

Dr. Ray Walford is also experimenting with calorie restriction. He has extended the lives of various small animals. Dr. Walford is a professor of pathology and a physician at UCLA Medical School. He is a firm believer that people can extend their life through manipulating their diet. Walford is in his late seventies and has been employing calorie restriction in his own life for the past 15 years.

*Simple Doesn't Always Mean Easy *

There are some obvious problems with employing this most fundamental anti-aging strategy. For one, it's very tough to do. Additionally there are some tradeoffs to living longer through permanent calorie restriction. You will grow smaller, your metabolic rate will drop and your sex hormones will plummet. The drop in testosterone in both men and women suppresses sex drive. If continued it causes a reversal of sexual characteristics like body hair and breast development. It appears nature doesn't want you to begin a family if you are starving.

Although we know it works, it's no surprise that long-term caloric restriction has failed to become popular. To employ this strategy, you must permanently reduce your caloric intake to about 2/3 of what it takes to maintain your current weight. An initial weight loss tapers off as the metabolism adjusts to a lower metabolic rate.

It is not possible to test this in the traditional model of controlled studies. You would have to control everything a person ate for an entire lifetime. There are, however a small but growing group who have decided to use themselves to test long-term calorie restriction.

They call themselves “Cronies”. Their philosophy is “calorie restriction with optimal nutrition”. Cronies have experimented with calorie restriction to the point that it is their only way of life. They know that the diet is working by monitoring their vital signs. Cronies look for drops in their temperature, sugar levels, blood pressure, and cholesterol. Long-living monkeys and rats placed on calorie restricted diets experience the same drops in vital signs.

This extreme approach to diet will extend life. But there are less extreme approaches.

* Lengthening Your Life Safely*

If you are highly motivated to slow aging, especially in the anticipation of the advent of more user-friendly anti-aging therapies within the next several years, you might want to consider shorter term caloric restriction as an interim strategy. Some anti-aging physicians advocate a modified version of caloric restriction, consisting of regular fasting for one or two days every 10 to 14 days. For many, this is more realistic.

And regular fasting has other anti-aging benefits. Fasting triggers increased production of human growth hormone, one of the most important anti-aging hormones, and one that declines dramatically after the age of 30.

In September 2001, Proceedings of the National Academy of Sciences made an exciting announcement. A new study revealed that short-term calorie restriction lengthens life. The scientists looked at 11,000 mouse genes that showed the effects of calorie restriction. Short-term calorie showed up in the genes very rapidly. The youthful effects could even be seen in older organisms that had never been previously calorie restricted. 1

If under eating is anti-aging there is even more evidence that overeating is age accelerating. The emerging evidence for the cellular mechanisms for caloric intake to affect aging is one more good reason to at the least avoid overeating.

Here are some strategies that will stop you from overeating and help you to work toward restricting your calories.

? Avoid high calorie foods
? Avoid eating late at night
? Stop eating once you are satisfied (leaving extra food on the plate)
? Don't eat while you are distracted ( as when watching TV)
? Try short-term fasting (for about two days at a time)

Al Sears, MD

1 Cao S. et al., Genomic profiling in short- and long-term caloric restriction effects in the liver of aging mice. Proceedings of the National Academy of Sciences, Sept. 11, 2001; 98(19): 10630-10635.