CR is a very simple program. It's the only "diet" that is entirely without hooks or pretentions. There are no manufactured foods you must buy, no trademarked fitness plans. There's not even a particular book you need buy.

Calorie Restriction (CR) is the process of limiting our caloric intake with the intention of slowing down aging. Some people refer to the concept as an anti aging diet. Research into Calorie Restriction has continued for many years - concluding that the lifespan of many animals (rats, monkeys, spiders) is extended when calorie intake is restricted.

The difficulty of Calorie Restriction is that sufficient nutrition (vitamins and minerals) must be maintained while lowering energy intake as much as possible.

There are many adherents of a calorie restricted lifestyle - hoping to extend life.



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Researchers evaluate health benefits of calorie restriction

(Republished with permission from the St. Louis Post-Dispatch. This article originally ran in the Health & Fitness section on Monday, February 18, 2008.)

By Harry Jackson Jr.
St. Louis Post-Dispatch

Washington University scientists want to find out if eating a lot less can improve your health to a nearly perfect condition.

That's why they're conducting human studies of a movement called "calorie restriction."

It's supposed to work this way: If you reduce your calorie intake by 25 percent to 30 percent, your physical fitness will improve to a nearly perfect level of health.

For example, a calculator used by the Mayo Clinic says an active man of 6 feet, 200 pounds, needs about 2,900 calories a day to maintain his weight. For a 25 percent reduction in calories, he'd go to 2,175 per day.

An active woman, 5-5, 140 pounds, needs 2,050 calories a day to maintain her weight. She'd drop to about 1,550 calories.

The first phase of CALERIE — Comprehensive Assessment of the Long Term Effects of Reducing Intake of Energy — began several years ago when doctors examined a small number of people from a group called the Calorie Restriction Society. The group has about 3,000 members.

Early tests showed the practitioners, who call themselves "CRONies," (Calorie Restriction, Optimal Nutrition), had virtually no risks of cardiovascular disease or cancer even though their medical records said they were less healthy when they started the program.

What also intrigued researchers were claims that practitioners would live 20 to 30 percent longer and in better health.

Dr. John Holloszy, professor of medicine in the Division of Geriatrics and Nutritional Sciences at Washington University School of Medicine and the lead researcher on the project, says researchers can't wait half a century to see if the longevity claims are true.

However, he wrote after the preliminary round of studies, "It's becoming clear from studies with the CRONies — and from this brief, prospective study — that calorie restriction does change some of the markers we associate with aging."

The federal National Institutes of Health agreed and is paying for a bigger study of several hundred people in three research centers — Boston, Baton Rouge, La., and St. Louis. These will be people new to calorie restriction.


Proponents of calorie restriction, which they call "CR," boast of disappearing triglycerides, healthy cholesterol levels, the elimination of low-level inflammation through the body caused by oxidation damage, lowered and more stable blood sugar, nonexistent cardiovascular disease and even instances of being cured of early stage diabetes.

Holloszy says he's not put off by claims that the practice could stretch useful and healthy life spans up to 120 years.

"With calorie restriction, it seems like the metabolism goes into slow motion," Holloszy says, adding that the slower metabolism means slower aging.

"We'll look at the (physiological changes) in the reduction of the processes that we know cause aging," Holloszy says.

He added that early research shows some health benefits can come from reducing calories by 10 or 15 percent. "We think the effects may hold true (in proportion). We just don't know yet."


A seven-year practitioner of calorie restriction is Joseph Cordell, a St. Louis divorce attorney who specializes in men's rights.

He adopted calorie restriction years ago. He was in good condition but wanted more. He read a book, "Beyond the 120 Year Diet" by Dr. Roy Walford, who's considered the founder of the movement. Walford believed the rodent tests would translate easily to humans even before human studies were performed.

Today, Cordell has a breakfast of berries and apple peels. Through the day he'll eat mainly vegetables, fruit and for dinner vegetables with a small amount of lean meat, such as salmon, chicken or even lean red meat.

"That's the thing about calorie restriction," Cordell says. "What I eat probably weighs more than what you're eating, but it's much more dense in nutrients and a lot fewer calories."


The attraction to CR by researchers was sparked by more than 60 years of uncommonly consistent tests on laboratory mice and rats, Holloszy says. When laboratory animals were placed on calorie restricted diets, "their life spans increased 20 to 40 percent."

Washington University performed the tests more than 10 years ago and came up with the same results, Holloszy said.

Bob Cavanaugh, a spokesman for the Calorie Restriction Society, says the group was founded on Walford's principles.

Thousands use the group's website,


Both Cavanaugh and Cordell emphasized that calorie restriction is a way of life, not a diet; it's not simply eating 25 percent fewer calories at each meal.

And it's not easy, which is why CR practitioners created a supportive community. St. Louis doesn't have a local group, although people here practice CR.

This is a simplified description:

— Examine your diet closely, detect the high-calorie, low nutrient foods, then eliminate them. They suggest weening, not simply turning them off cold turkey.

This will involve logging what you eat, maybe even seeking help from dietitians or other CR practitioners.

— As you eliminate empty calories, replace them with nutrient-dense foods, primarily vegetables and fruits. Cordell says he eats apple peels rather than the whole apple because that's the source of the most nutrients. He also avoids high-sugar fruit such as pineapples.

— Once your whole diet is nutrient-dense foods, you can calculate the calories you're eating and begin cutting back until you've eliminated 25-30 percent.

Cavanaugh says the CR Society offers a calorie and nutrition calculator to anyone who pays the $35 signup fee. Another, called "Cron-o-meter," is free online.

Holloszy, however, recommended against doing this on your own because off the downsides. And even the CR Society lists risks, most of which come during the transition process.

For example, practitioners find that they lose both fat, muscle and bone mass. That's why people who can't afford loss of bone mass or muscle need to be cautious or reject CR alone or work closely with their personal physician.

As for others, "The body is marvelous at regulating itself," Cordell says. "Your body maintains the amount of bone mass and muscle you need for good health. If you're not carrying around so much weight, you don't need the bone mass or muscle mass."

He says he dropped to about 130 pounds from 170, living on about 1,500 calories a day.

Holloszy wasn't ready to dismiss the loss of bone mass and muscle. He suggested daily exercise for people trying CR.


For maximum safety, Holloszy suggests joining the Washington University study. Researchers still need about 60 people.

Those accepted will be monitored by physicians, dietitians and physiologists who'll meet with them weekly and help set up their diets.

The first month will be a tightly scrutinized eating plan to get you started. After "boot camp," participants will be be given a stack of eating plans and recipes from various diets such as the Mediterranean Diet and diets based on low fat, low glycemic index or vegetarian.

For two years, they'll have weekly contacts with the researchers and frequent blood tests.

"It's quite a commitment," Holloszy says.

The only scientific proven way to increase longevity. In 1935 it was found that the lifespan of laboratory rats could be extended by as much as 50% on severely calorie restricted diets, the rodent equivalent of a human life stretched past the age of 160. And it isn’t just a mouse. Yeast cells, spiders, worms, monkeys have all been shown to benefit from CR’s life-extending effects.

In 1991 a team of eight bioscientists sealed themselves up for a two-year stint inside a giant, airtight terrarium in the Arizona desert, and promptly discovered that the hypothetically self-sustaining ecosystem they’d settled into could barely grow enough food to keep them alive.

This revelation might have doomed the experiment (known as Biosphere 2) but for the fact that the team’s physician, UCLA pathologist Roy Walford, had been studying Calorie Restriction for decades and convinced his fellow scientists that—as long as they all ate carefully enough to get their daily share of essential nutrients—a year or two of near starvation wouldn’t hurt.

When at last the Biosphere 2 crew emerged from their bubble, tests proved them healthier in nearly every nutritionally relevant respect than when they’d gone in, and the case for Calorie Restriction in humans was no longer purely circumstantial.

So what are the benefits of CR?

Dr. John Holloszy, principal investigator of a long term study on CR has this to say, "There's no chance of CR practitioners getting type 2 diabetes, they have very low blood pressure, and the risk of them developing heart disease and cancer is markedly decreased," "The calorie restriction protects them from the same diseases that exercise protects against, and more potently than exercise,"

And exercise? Not an option as C.R. dieters simply don't have the calories for it, unless they increase their calories accordingly.

Dr Hellerstein a professor at UC Berkeley, says "It's the only thing that is known to extend the life span in animals," he studies human nutrition and metabolism. He recently started recruiting people for a study where subjects will eat a near-fasting diet every other day, alternated with a normal one. "It's the most amazing thing in all of biology."

And there is a growing impetus to find out if humans reap the same benefits, over time, as lab animals. The Baby Boomers are aging, and just as they felt the need to revolutionize attitudes toward child rearing and midlife, they are interested in a better old age. They are the ones who promoted 50 as the new 40. Could 100 will be the next 90 - or 80?

The National Institute on Aging and National Institutes of Health are both funding research at major universities. Private industry is also studying the metabolic effects of CR, working to create a pill that will mimic it and bypass the need for a rigid diet.

An example is 47 year old Joseph Cordell who eats about 30 % fewer calories than most people. The recommended minimum is 2,500 calories for adult males. Those males practicing CR commonly consume 1800 to 2000 calories daily while some women might consume as few as 1300 calories to 1500 calories daily.

Cordell's doctor says that he has the blood pressure of a child, the cholesterol of a teenager, and his risk of heart disease is close to zero. Average middle-aged men have 23 to 25 percent body fat; Cordell's is 7 percent.
"If there wasn't a substantial benefit to C.R., no one would do it," he says.

For Cordell, the potential payoff is worth eating this way, something many of us might have a hard time with. It's not about a short term New Year’s resolution; it's about a complete diet overhaul that Cordell will stay on for what he believes will be a longer, healthier life.

Barry Gamble a 67 year old CR advocate says his benefits are more energy, fewer digestive problems, better measures of heart health and mobility than his peers and although there are no guarantees, a longer life. "The real reason I do it is because I feel better.”

The focus of those practicing CR is health. Nobody is trying to figure out how to eat less and disappear. The constant thought is, ‘How can I pack more nutrition into my calories?’

Theory of how CR promotes longevity

Inside our cells the process of cellular respiration breaks down a molecule of glucose into carbon dioxide, water, and energy. This energy is stored as ATP. An adult produces 70kg of ATP a day. The process of breaking down sugar in the body is not completely efficient. About 40% of the sugar is converted into ATP. A significant amount of free radicals are produced during this process. When calories are restricted our bodies rely more on fat stores as fuel.

Since fat consumption is several times as efficient at producing ATP than burning glucose, the same amount of energy can be created with much lower levels of free radicals. Fewer free radicals mean lower levels of free radical damage particularly to the mitochondria. Recent studies have shown that a calorie restriction of 40% leads to a 45% decrease in the rate of mitochondrial free radical generation and a 30% reduction in the level of oxidative damage to mitochondrial DNA.

The net effect of these changes decreases the rate of aging by about 50%. Unfortunately humans cannot live reasonably by cutting 40% of their calorie intake. But by decreasing our calorie intake by 15% one achieves almost as much of an anti-aging benefit. It becomes a more realistic achievement than the tough 30% reduction often used by the calorie restriction purists.

CR followers say it is "a way of living" instead of a diet. The Calorie Restriction Society, based on the work of the late UCLA gerontology researcher Roy Walford, was founded in 1994 by a small group of people interested in the science behind CR and an estimated 1,400 people have taken up the diet as a full-time, lifelong practice.

What should you do while waiting for the long term human studies? If you are overweight or you want to experience the potential anti-aging benefits of CR it would be prudent to reduce calories by 15%.

We need to work together with our health practitioner and monitor our blood levels of glucose, insulin, cholesterol and inflammation levels. We need to do this slowly over time and according to the CR followers we will then experience optimal health.