John O. Holloszy, M.D., professor of medicine at the Washington University School of Medicine in St. Louis, has shown that people who eat a very low-calorie diet are protected against heart disease and diabetes. (Credit: Washington University School of Medicine.)
Those on calorie-restricted diets are less prone to heart disease and diabetes, says Washington U. researcher John Holloszy.
There is ample evidence that a severe low-calorie diet can increase longevity in a number of animals, including flies and rodents. But does it work in humans? Scientists at Washington University in St. Louis are hoping to answer that question by studying a group of people -- 35 members of the Calorie Restriction Society -- who eat around 1,800 calories a day in an effort to improve their health and extend lifespan.
It will be years before the study, which began four years ago, determines how the diet affects lifespan. But John Holloszy and his collaborator Luigi Fontana have already found that those following such a calorie-restricted diet -- they call themselves "CRONies" (Caloric Restriction with Optimal Nutrition) -- are protected against some diseases associated with aging, such as cardiovascular disease and Type 2 diabetes. The researchers are now planning a larger trial, in which people eating an average diet will reduce their caloric intake by 25 percent, to determine how caloric restriction leads to biological changes over time.
Holloszy talked with Technology Review about his current findings at the 35th annual meeting of the American Aging Association in Boston this week.
Technology Review: What's the most striking finding you've seen in those following a calorie-restricted diet so far?
John Holloszy: They are powerfully protected against the diseases of old age, such as heart disease. They have low levels of cholesterol and triglycerides and extremely low blood pressure -- similar to a young child, around 100/60. As a result of the low blood pressure, they have less strain on the arteries, which are much more elastic than usual for people of their age. Their hearts resemble the heart of a person 17 years younger. They also have very good insulin sensitivity, so they are not going to get Type 2 diabetes.
TR: What about their levels of inflammation? That is another factor that's been the focus of a lot of aging research in the last few years.
JH: As we get older, we get an increasing amount of inflammation, which is probably a very important part of the aging process. CRONies have very low levels of inflammation. C reactive protein, for example, is a marker and cause of inflammation. An average value for a middle-age person is about 2.5; but CRONies have levels of 0.2. It's just amazing.
TR: So are these people going to live longer?
JH: Caloric restriction definitely does slow secondary aging, which is linked to lifestyle and disease. Smoking, for example, causes secondary aging of the lungs and skin. It's impossible to say if they'll increase their maximum lifespan. But I'm sure they'll live longer than they would if they didn't do caloric restriction.
TR: You also compared them to a group of runners to see how caloric restriction measures up to exercise.
JH: Yes. We studied a group of master athletes, who are the thinnest group of people eating regular diets that we could find. They were very lean, but not as thin as the CRONies. It's hard to find anyone that thin, unless they're sick.
The diet delays or prevents diabetes, cancer, heart disease, and brain atrophy.
Rapamycin, an immunosuppressant, enables elderly mice to live longer.
A trial in humans suggests that calorie restriction can boost memory.
Guest (Steve too)
How do these low calorie types fuel exercise. Do you have to give that up?
Guest (John)
CRONies exercise like everyone else: just as they choose to. Some do zero - some run - some lift weights. It is not a religion where you have to play by any rules - beyond reducing caloric intake
Guest (Mark)
This is not entirely true. Intense exercise, long distance running for example, burns lots of calories. You couldn’t do as much on a severely calorie-restricted diet. You simply wouldn’t maintain enough calories to live.
This is why such aerobic exercise is both age-fighting and aging. It improves muscle tone, cardiovascular fitness, etc. At the same time, however, the burning of so many calories is a source of the oxidization which CRON seeks to avoid.
The CRONies are quick to point out that consuming more calories but burning them off through an active lifestyle does not equate to calorie restriction.
Guest (aymeric)
What kind of life is it that one leeds for decades. Counting all calories, never truly enjoying a meal. And why this obsession with longevity. I would rather have a fun filled life and only reach 70 than being miserable until I am 120.
Guest (Ron Wagner)
Good point. Especially if you died of an illness at 70 years old, because you didn't have the reserve fat you needed.
Guest (John)
In America there is right to pursue happiness. If people choose that counting calories for 120 years, they have a right to do so. All CRONies seem to start with the attitude: "I'm going to try it - if I don't like it I can quit.
Guest (GG)
wrong point on quality of life
No, they don't count calories for years. The calorie count only happens in the beginning of the project, for weeks or months at most. Once you get used to the ballpark of what low calories means, it becomes second nature - you do it without thinking about it.
As for being miserable???? You guys are NUTS!!! How about being miserable from diabetes and all its complications...and from all the other life style diseases, as well.
As for mental capacity? Look around, and you'll see a statistical trend - obesity is inversely proportional to IQ.
I haven't seen a dumb skinny person, ever.
Guest (Richard)
It is a common statement. "I would rather do X for X years." One mistake is to see it as simply a longevity issue. A vegetarian will not only, on average, live longer but be healthy longer. A fat person's last decade or more will be painful and expensive. I remember a quote from a vegie doctor, "We want to make it so your first heart attack is your last one as well."
Guest (aymeric)
just go to west virginia...plenty of rail thin dumb hicks around...I am just amazed at this obsession with living long
Guest (CatoTheElderII)
Actually, my take is that for a certain class of people who perhaps work on very long term projects such as the creation of global literary systems, or projects that require a great deal of time to complete a long life could be both productive and rewarding. For most people however I tend to think that long life would equal long misery and not be worth the effort.
Guest (John)
I tend to think most people love life and want it to go on for a long time. Only a small number of people choose to die. I agree that most people think CRON would not be worth the effort. I think that can even be proven - given that so few people choose it
Guest (bill)
My Granny, born in the early 1900's, ate what ever she wanted and never exercised. In old age she had type 2 diabetes and high blood pressure but she never lost a limb or went senile (she did suffer some strokes at the very end). She died peacefully at 95. Just like global worming there are a ton more factors at play here. There's no magic bullet.
Guest (John)
Yes, there are a lot of factors at play. There is no magic bullet or magic anything. What CRONies believe is that your Granny might have lived even longer and not had died so young, and that she would not have suffered from diabetes or HBP, if she has practiced CRON. There is no proof of that, just a lot of evidence that suggests it.
Guest (Bob)
I wonder what distinguishes people who severely restrict their caloric intake from people who suffer from anorexia nervosa. I suppose that one group is thinking about health while the other is thinking about appearance. I'm all in favor of seeing what the research tells us. But I fear that this could become a fad, especially among young women.
Guest (John)
Did you mean: What's the difference between "severe" CRONies and those what suffer from AN? A big difference is that the CRONie knows mal-nutrition is a concern, and thus monitors his/her health, and will adjust their diet accordingly. AN generally do not do any of these things. It is a common fear that CRON will lead to AN. So far there is no evidence of that ever occuring.
Guest (George)
I have seen multiple reports and several studies about extending lifespan both in humans and other animals, but never any results of caloric restriction on mental abilities of these subjects. Humans under caloric restriction report feeling cold constantly and often somewhat depressed (not suprising - all they have to do is look in the mirror). Have mice under CR been tested using mazes and other "brain teasers"? Given the importance of fat in the brain, I would be surprised if CR had no effect on the various mental activities from coordination to learning and memory.
Guest (John)
Yes, mice have been tested. It has nothing to do with fats. Try neurotransmitters. We can say that it doesn't have to do with fats because if it has to do with fats, then it ain't caloric restriction. Rather it would refer to caloric restriction PLUS fat restriction. The ON part of CRON requires all essential nutrients -including fats are included. If there ain't enough fat for the brain to work, you ain't eating enough fat. Of coarse if you are fat, it is OK to believe you should eat more to make sure your brain works.
Guest (George)
John - could you point us to some studies you refer to on the mental effects...I'm quite interested due to the new reports on Grehlin that indicate increased mental accuity during fasting...Thanks
Guest (Jonathan Schattke)
I've been living on ~1600-1800 calories daily average intake. I'm a genius. I also suffer from dysthymia, so maybe I'd be more of a genius if I ate "normally" :-)
Guest (brunascle)
AFAIK, a calorie is actually a measurement of the amount of energy in food. So basically, a restricted calorie diet is like giving your body a smaller battery. If you give your body too small of a battery, you won't be able to function to its full capacity. Give your body too large a battery, and it tries to store the extra energy for use later on, which, in excess, can negatively impact your health.
Instead of simply reducing calories, I think it's more important for someone to find their target calorie intake.
Guest (John)
How does someone find their target calorie intake? That's the $64,000 question. CRONies are doing the best to find what target works best for them
Guest (brunascle)
Exactly, it's very hard. The best someone could do is guess and check.
I think the main conclusion of the study is that a calorie-focused diet is very healthy, which i totally agree with. Most of us (Americans) probably have a target intake that's lower than our normal diet. But a "calorie-restricted" rather than "calorie-focused" label might give the false impression that the less you eat, the healthier you are.
Guest (Richard)
I wonder if combining a gastric pacemaker with CRON would make it easier to tolerate?
Guest (Derek Edwards)
All this talk of longevity tends to obscure one of the most important factors for most CRONies: a healthier life. We seek to die of old age, not disease.
Guest (Marco)
All you genius's have forgotten one key to perfection in all things Carnal and Spiritual - Balance ! Be able to say that I am in balance.
I do not tip anyway but stay in the middle.
I'm guessing that a lot of respondents are 20- and 30-somethings. I'm 58, and I've been abstinent from recreational drugs, alcohol, and red meat for over 20 years. Nevertheless, I have been diagnosed with Progressive Supranuclear Palsy, a condition which will likely end my life within the next decade. Because free radicals are implicated in this poorly understood disease, and since they are a byproduct of food metabolism, I'm looking into CRON as a way of managing my disease and lengthening my life. I don't want to live to a hundred but it would be nice to see 80 without a feeding tube. I'd also like to accompany my partner, 11 years my junior, a bit further along on his journey. I'm not trying to cheat the Grim Reaper, just deliver a feint or two before I give up the fight.
Stay healthy all of you, love life and one another.
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Guest (Steve)
Caloric Restriction
Interesting research. But it should be noted that such a diet increases the risk of influenza and other infectious diseases at every stage of life. A parallel statement would be, "People who deliberately amputate both legs are far less prone to foot disease."
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Guest (Ron Wagner)
Needed fat?
I am an RN, and wonder if you would have many losses of life due to not being able to survive infection, trauma etc.
My brother in law just lost eighty pounds during a lung infection complicated by a pocket of asbestos that had to be removed surgically. His doctor said he would have died without the reserve fat. He was not an obese person by normal standards.
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Guest (John)
Nobody knows
We don't even know if CRON can work in humans - or how to impliment it. The most common theory for those practicing it: The risks of dying/suffering (e.g. from reduced reserve fat) are fewer than the risks from not doing it. No enlightened CRONie says that it will (beyond all reasonable doubt) make them live longer. Life is filled with risk.
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