Low-carb is just that..........low amounts of carbohydrates. Less than 100grams of quality carbs per day. Many people associate low-carb with only the induction phase of the atkins diet. Low-carb is the way your body is desinged to live. Your body does not "need" carbohydrates. Yes, carbs are most easily converted to energy but your body is also designed to convert fat and protein to energy. Without protein and fat, you will eventually DIE! That meets the definition of "need."
Atkins, South Beach, etc... are methods of eating low-carb and you can choose to do them or not. No matter how you choose to eat or lose weight, limiting your carbohydrate intake it the proper way for every human to eat. It doesn't matter if you are fat, thin, athletic, or lazy. The human body is desinged to digest mostly protein and fats. The primary reason to eat carbs is for the vitamins, minerals, and fiber found in these foods.
Low carb is not a fad. It is simply proper nutrition.
There have been a few arguments lately about this and I just wanted to clear things up.

Well you do NEED carbs. Your brain cannot use fats or proteins. Plus you said if you don't have fats and proteins you will die. Well why do you think your body makes it easiest to use carbs for energy because maybe it wants to save the fats and proteins? So really you NEED all three. Also if your body is stressed is saves the carbs for the brain. So your body uses just proteins and fats and if that goes on for a long time it leads to body weakness, and possibly death. So I guess i could be wrong and just don't understand things correctly but it seems like carbs are a NEED. Just if you aren't a very active person you don't need as many. But if you are an athlete and are putting tons of stress on your body then yes you do need more than people who are couch potatos.

Well you do NEED carbs. Your brain cannot use fats or proteins. Plus you said if you don't have fats and proteins you will die. Well why do you think your body makes it easiest to use carbs for energy because maybe it wants to save the fats and proteins? So really you NEED all three. Also if your body is stressed is saves the carbs for the brain. So your body uses just proteins and fats and if that goes on for a long time it leads to body weakness, and possibly death. So I guess i could be wrong and just don't understand things correctly but it seems like carbs are a NEED. Just if you aren't a very active person you don't need as many. But if you are an athlete and are putting tons of stress on your body then yes you do need more than people who are couch potatos.

Your body converts fat into ketones, which your brain then uses for fuel. Humans can live long healthy lives without digesting a single carbohydrate.

Humans can live long healthy lives without digesting a single carbohydrate.

Is that so? How long?

Is that so? How long?
Well, at least for a year, probably longer. There was a study done in the 1930's where two men went on a hospital supervised all meat diet that lasted for one year. They experienced no negative side effects and came out of the study in better shape than when they started.

One of the participants in the study was Vilhjalmur Stefansson, the artic explorer. With his experience and observations of arctic native cultures, he realized that many primitive cultures subsisted on almost exclusive meat diets for many months of the year. He in fact lived for nearly 5 years with the Eskimos (Inuit) eating their native diet of meat and fish and little else.

The year long experiment took place at Bellevue Hospital, New York. The study was designed to find the answers to these questions:

Does the withholding of vegetable foods cause scurvy?
Will an all-meat diet cause other deficiency diseases?
Will it cause mineral deficiencies, of calcium in particular?
Will it have a harmful effect on the heart, blood vessels or kidneys?
Will it promote the growth of harmful bacteria in the gut?

The results of the year-long trial were published in 1930 in the Journal of Biological Chemistry and showed that the answer to all of the questions was: NO. There were no deficiency problems; the two men remained perfectly healthy. The diet consisted of ~2000 - 3000 calories per day of meats (much of it raw) including fat (much fat in fact). Fat made up about 80% of their calorie intake.

For more information, just do a search for [Stefansson Bellevue].

In the 20s, their knowledge about health and diet was questionable at best.

I have found some the studies/observations from the early 20th century (and much earlier) very interesting. The open-minded inquiry is very refreshing . . . and I find the pairing of effect with cause more relevant in some cases.

It is astounding to me how unscientific some modern research is.

Here is my interest with this, Arkie and Neno. When determining what is a proper human diet, as in "Low carb is not a fad. It is simply proper nutrition." it is important to me to take into consideration human life span. I am involved in the Caloric Restriction Optimal Nutrition community of life extensionists and I am continuously reading scientific literature on human life span. Caloric restriction has been shown to increase the lifespan of laboratory animals, sometimes doubling it, and enhance health and vigor into old age. Now scientists speculate that caloric restriction may be working on behalf of protein restriction, and not overall calorie consumption. Of course, this is only speculation at this point. However, where lifespan is concerned, a high carbohydrate diet of vegetables and fruits has always outshined high protein counterparts. We can see this with the median lifespan of the Alaskan Inuits, and hunter-gatherer type groups which favor more animal protein. However, then you have to take into consideration "occupational" hazards, and still births, child mortality etc, that effect median lifespan. Clearly if you are living in an agricultural society you will have more possibilities for a longer lifespan, however, the number of centenarians living in Okinawa, eating a low calorie, plant based, high carbohydrate diet with the addition of fish and some pork as the main source of animal protein is very intriguing. If protein restriction, or caloric restricted, high carbohydrate, plant based diets allow people to live longer and healthier then isn't saying low carb is the way we are meant to eat (as in "Low carb is not a fad. It is simply proper nutrition. ") saying that humans are meant to enjoy shorter lifespans?

There is no argument from me that grains cause problems for people, but that is only one type of "carb" and I think most of the perceived health benefits of low carbing come simply from the omitting of grains, because clearly you can live long healthy lives eating 70% carbohydrates from highly nutritious vegetable matter, and fruit...perhaps even longer than animal protein based diets.

If I can't live as long eating only protein and fat, as I can eating a high carbohydrate diet of mostly plant matter, then eating only protein and fat doesn't constitute proper nutrition, in my point of view.

In other words, if I need nutrient rich, low calorie, low protein vegetables in order to enjoy a longer lifespan, then clearly that is how I, as a human being, am meant to eat.

here's a summary of three studies, each following more than 11,000 individuals, finding no difference in death rates (longevity, lifespan) between vegetarians and non-v

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12936946&dopt=Abstract

Here's a study that says if you are too slim, that will increase mortality (cut longevity), so the calorie restriction approach would seem to have important limits:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12540689&dopt=Abstract

And in fairnessto your point of view, here's one large,prospective study that found reduced rates of death from ischemic heart disease among vegetarians, although no difference in any other cause of death:

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10555529&dopt=Abstract

So, there is some evidence on either side of the question I believe you are posing. Certainly there is no clear, unavoidable trend in the data leading to a single conclusion.

The biggest problem with the studies I've seen--which certainly cannot be more than a tiny fraction of what's out there--is the absence of control for confoudning variables like smoking. Vegetarians--in other studies--are found less likely to smoke. Are there other such factors that confuse mortality rate comparisons? I don't think we know--unless a lot of work has been done that I just haven't stumbled on. Very possible--I don't do this for a living!

Interesting question


sean

Very interesting post, prometheus. Yeah, I first heard about the caloric restriction regimes MANY years ago. (At that point, I seem to recall, an experiment with cows [nice big mammals, rather than the usual rats] had been completed.)

One doesn't know what to make of all this information. On another site someone was claiming that Okinawins eat a whole lot more pork than is usually portrayed. I don't know. But who are some of the comparator groups who were eating more carbohydrates, less animal protein, and living longer?

Another factor is a person's current state of "health". In my case, IMHO, years of eating refined carbohydrates had shot my pancreas to h*ll.
I simply could not have sustained a switch to something like caloric restriction. Absolutely no way. What did help was low carbing. In retrospect, I think it was good (and essential) to cut back on carbohydrates (most carbohydrates, not just the "bad" ones) for a while and let my pancreas and other digestive-related organs heal; and I have come to believe that even more than the low carb (or animal protein), it is the fat that has helped that along.

So in terms of longevity . . . if you looked at my life expectancy a couple of years ago, I am quite certain it is longer today (of course, we cannot prove it, though there are some positive medical indicators).

Yes, Sean the biggest problem with those types of demographic studies is always confounding variables. The Okinawans have remarkably healthy lifestyles, deep cultural roots, and tight knit communities. They also eat less calories (which would always be the case with less animal meat), drink rich mineral water, and breathe relatively less polluted air than we do. Now, so do the Hunzas. I know you, Aunty, asked me what the other comparitor groups are who eat more carbohydrates, less animal protein, and live longer. Well, the only population in the world that lives longer than the Okinawans are the Hunzas, and they eat no animal meat whatsoever (if they do it is a small amount of ceremonial meat/bones and no more than once a week). These are the people who get their vitamin B12 from growing their plants in "Nightsoil" and they, as a population, are the longest lived in the world.

Back to confounding variables. You are absolutely correct that calorie restriction has important limits, and risks, Sean. CR has been shown to dramatically extend both the life and health of all animal species tested to date. Yes, that includes cows, Aunty. ;) In all laboratory studies CR resulted in life extension, a pattern that holds until CR becomes actual starvation, whereupon it shortens lifespan. So we as CRONies try to walk the fine line between calorie restriction and starvation. That is where optimal nutrition comes in. While early demographic studies such as the one you example, suggest that lower body weight is associated with increased mortality, once researchers account for factors such as smoking and illness-induced weight loss and starvation, the data shows a correlation between lower weights and increased longevity.

NIHNC, CDC, & DHHS. (1985). Body weight, health and longevity: conclusions and recommendations of the workshop. Nutrition Reviews, February, 43(2), pages 61-3.

Lee IM. et al. (1993). Body weight and mortality. A 27-year follow-up of middle-aged men. Journal of the American Medical Association, December 15, 270(23), pages 2823-8.

Manson E. et al. (1995). Body wight and mortality among women. New England Journal of Medicine, September 14, 333(11), pages 677-85.

Solomon CG. (1997). Obesity and mortality: a review of the epidemiologic data. American Journal of Clinical Nutrition, October, 66(4 Suppl), pages 1044S-1050S.

Aunty, yes one must realize that individual health or individual illness has its own dietary needs but if, as this information tends to favor, humans as a whole benefit from the low caloric, nutrient rich, low protein value of plant matter, with increased longevity and vitality into old age, then that is how humans are meant to eat. That is proper nutrition. If humans as a whole can't do it on animal meat, protein and fat, alone, then saying protein and fat is "simply proper nutrition" is saying humans are meant to enjoy shorter lifespans.

Prometheus...everyday you amaze me more and more with your extensive knowledge on the subject of nutrition. Plus you always back up your sources and always seem to have an answer for everything! Thanks for all of the info you provide on these boards :)

Prometheus,

Thanks,
I've been interested in the subject of longevity through low bodyweight for several months (since the NY Times did a long feature on it.)

Of course, now there's the actual DOING it.:D:D Caloric restriction for me has always meant <2500 calories (but in my defense, I'm quite large.). Good plant food seems to be SO difficult for urban dwellers these days....especially in the dead of winter (with the "cotton" tomatoes.) I ijmagine I need to be thinking in terms of <2000 (or MUCH<) :eek: :eek: !

I agree, we need protein to replace (protein breakdown-recycling of amino acids); this is not a huge amount in a grown man. Using it for heat and energy is NOT what it was designed for...nature didn't throw amines and their nitrogen into every protein molecule simply to irritate the kidneys as acidic nitrogenous waste material.
And since the body can make fat from an excess of ANY food, how much of any animal's excess fat is useful to a human...it's hard to burn with an acidic residue (loosely called ketone bodies) and is usually the relatively safe storage location for many poisons that the body wants safely out of the way. Perhaps we might not NEED an animals stored poisons.

How low is your weight?

Yes, Sean the biggest problem with those types of demographic studies is always confounding variables. The Okinawans have remarkably healthy lifestyles, deep cultural roots, and tight knit communities. They also eat less calories (which would always be the case with less animal meat), drink rich mineral water, and breathe relatively less polluted air than we do. Now, so do the Hunzas. I know you, Aunty, asked me what the other comparitor groups are who eat more carbohydrates, less animal protein, and live longer. Well, the only population in the world that lives longer than the Okinawans are the Hunzas, and they eat no animal meat whatsoever (if they do it is a small amount of ceremonial meat/bones and no more than once a week). These are the people who get their vitamin B12 from growing their plants in "Nightsoil" and they, as a population, are the longest lived in the world.

Back to confounding variables. You are absolutely correct that calorie restriction has important limits, and risks, Sean. CR has been shown to dramatically extend both the life and health of all animal species tested to date. Yes, that includes cows, Aunty. ;) In all laboratory studies CR resulted in life extension, a pattern that holds until CR becomes actual starvation, whereupon it shortens lifespan. So we as CRONies try to walk the fine line between calorie restriction and starvation. That is where optimal nutrition comes in. While early demographic studies such as the one you example, suggest that lower body weight is associated with increased mortality, once researchers account for factors such as smoking and illness-induced weight loss and starvation, the data shows a correlation between lower weights and increased longevity.

NIHNC, CDC, & DHHS. (1985). Body weight, health and longevity: conclusions and recommendations of the workshop. Nutrition Reviews, February, 43(2), pages 61-3.

Lee IM. et al. (1993). Body weight and mortality. A 27-year follow-up of middle-aged men. Journal of the American Medical Association, December 15, 270(23), pages 2823-8.

Manson E. et al. (1995). Body wight and mortality among women. New England Journal of Medicine, September 14, 333(11), pages 677-85.

Solomon CG. (1997). Obesity and mortality: a review of the epidemiologic data. American Journal of Clinical Nutrition, October, 66(4 Suppl), pages 1044S-1050S.

Aunty, yes one must realize that individual health or individual illness has its own dietary needs but if, as this information tends to favor, humans as a whole benefit from the low caloric, nutrient rich, low protein value of plant matter, with increased longevity and vitality into old age, then that is how humans are meant to eat. That is proper nutrition. If humans as a whole can't do it on animal meat, protein and fat, alone, then saying protein and fat is "simply proper nutrition" is saying humans are meant to enjoy shorter lifespans.


Okinawans eat lots of fish--the longest lived okinawans eat the most fish (and seaweed!), and sleep the most soundly.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=12047577&dopt=Abstract

I'm having trouble finding anything in the peer-reviewed journals on the Hunza, but I suppose it must be there....can you help?

Late edit: Here's a study that says okinawa does have more centenarians per capita than other areas of japan, and that their life span correlates with less energy intake (your point), and HIGHER protein intake. (Hmmmm....) And yes, their protein was both vegetable and animal in origin. fish again.

http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=7500551&dopt=Abstract

So, eat less, but make sure the balance of your diet is high protein? That would seem to be the example here.

sean

. . . but if, as this information tends to favor, humans as a whole benefit from the low caloric, nutrient rich, low protein value of plant matter, with increased longevity and vitality into old age, then that is how humans are meant to eat. That is proper nutrition. If humans as a whole can't do it on animal meat, protein and fat, alone, then saying protein and fat is "simply proper nutrition" is saying humans are meant to enjoy shorter lifespans.

You have quite a number of "ifs" here. And there are variables and combinations that have not been considered. Hopefully, one day, there will be enough open-minded research to figure out what the important nutritional components are for longevity and overall health. But then there are things, like culture values (which are undeniably a factor in Japanese longevity) that need to be feed into the equation, too.

Do you think "humans as a whole" are following Atkins? I don't. On the question of safety and longevity, I think most people following Atkins are on a safer eating plan than they had been following and are lengthening their lives compared with what it would have been before Atkins.

Aunty, yes I have many emphasized "ifs" there to show that it is speculation. I don't want anyone to run out and become vegans, because of a query. I also don't want anyone to ignore the question because of lack of "good enough" evidence...but on speculation, I take a very conservative approach to diet, myself. You don't see me running out to become a vegan instead of a calorie restricter, which is what I am. I am taking a conservative approach and going with what has a proven track record, low calorie, relatively high carbohydrate (relative to calorie) ratio to fat and protein. There are no long-term scientific studies to support the overall efficacy and safety alleged of high protein diets. Two thirds of the calorie intake of the Okinawans, who have the most peer-reviewed centenarians to date, is carbohydrates.

Hey there Meagan! Good to see you over here. I've been wandering a bit. lol, I only appear to have "an answer to everything" because I read a lot and scientific materials all the time which are full of debates. I assure you there are no answers. All you would have to do is read some of the stuff I do to see that. Most of the CR society is composed of biologists, microbiologists, doctors, chemists, highly intelligent, educated professionals, (then there is me. lol) and they disagree ALL THE TIME. It is wonderful. Most of what they disagree on has to do with what exactly is Optimal Nutrition and what exactly is an Optimum amount of protein. (The FAO/WHO group recommends a dietary protein intake of 6-8 percent of calories, while the USDA suggests 14-18% of total energy intake to be derived from protein.) The protein restriction camp is radical, and small, and to be fair is concertly opposed.

However, it is not without merit.

Sean, yes it would seem to be the case. However, I would wonder if this is indicitive of the quality of the food, or the specific combinations of foods, such as certain vegetables or, in this case, seaweeds, the omission of which would lend a smaller protein count, or would compromise nutrition (compared to the other Okinawans). Afterall, calorie restriction works to extend lifespan only with adequate nutrition. Better or optimal nutrition should extend lifespan even further. I suppose your interpretation of Okinawans eating more seaweed (and fish) living longer than other Okinawans, is indicative of the beneficial aspects of protein, namely fish protein, and that one should strive to calorie restrict but focus on protein. Would you say this would carry over into believing that you could live as long as the Okinawans eating only protein and fat (animal meat), as long as it was calorie restricted? That is precisely my interest here. If you are calorie restricted chances are you eat less protein, specifically animal protein, than those who are not calorically restricted.

Now, take a look at some laboratory studies on protein, the conclusion of which is that dietary restriction of protein can extend lifespan provided a balanced level of essential amino acids is present in the diet, via the decrease of cellular protein synthesis. Denham Harman described an experiment in which mice on a diet of 20% protein from soybean lived 13% longer than mice on a diet of 20% protein from casein. Casein is higher in the amino acids histidine and lysine and lysine in particular is the amino acid most involved in non-enzymatic glycosylation (cross-linking) of protein. Harman asserted that histidine and lysine are the most easily oxidized amino acids and are contributory to free-radical oxidation. He then added 1% histidine and 1% lysine to 20% casein formulas and thereby reduced life expectancy by 4.8% and 6.2%, respectively (AGE Vol.1, p.143-150, October 1978). Now, neither casein nor whey protein are deficient in any of the essential amino acids. The only essential amino acid that is particularly low in soy protein is methionine. In Pearson&Shaw's book LIFE EXTENSION they comment that methionine can be converted to the pro-oxidant homocysteine, which is then converted to the anti-oxidant cystothione at the aid of Vitamin B6. A diet deficient in vitamin B6 relative to the amount of methionine could, in theory, reduce lifespan or promote cardiovascular disease. Further a diet supplying adequate vitamin B6 would offset the harmful effects of methionine...but why not just reduce the methionine? On DNA Damage and the further benefits of protein restriction, other studies evidence that the restriction of the amino acids tryptophan or methionine extends the lifespan of rats. The two main vegetable foods, corn and cassava, are deficient in amino acids. Corn lacks tryptophan and cassava methionine. The mRNA levels for a number of proteins in rat liver were depressed by about 40 percent after three days on a protein-free diet, with mRNA levels returning to normal after 3 days of feeding a high protein diet. Further, hepatic microsomal mixed function oxidase, epoxide hydrase and benzo(a)pyrene monooxygenase activities are decreased by protein restriction, resulting in less metabolite covalent binding to DNA (less damage). A high protein diet enhanced preneoplastic lesion development, while a low protein diet caused a disappearance of the lesions. Protein restriction exerts its strongest influence on lesion growth long after the genetic damage had occurred. High protein consumption enhanced carcinogen-induced mammary carcinogenesis (breast cancer).

"Life Span Extension" F.C. Ludwig ed., 1991 Springer.

Here are some more. I'm not sure I can post a full abstract but they are there for the reading.

J Nutr 1993 Feb;123(2):269-74

"Low methionine ingestion by rats extends life span."

Orentreich N, Matias JR, DeFelice A, Zimmerman JA.

Orentreich Foundation for the Advancement of Science, Inc., Biomedical
Research Station, Cold Spring-on-Hudson, NY 10516.


FASEB J 1994 Dec;8(15):1302-7

"Methionine restriction increases blood glutathione and longevity in F344
rats."

Richie JP Jr, Leutzinger Y, Parthasarathy S, Malloy V, Orentreich N,
Zimmerman JA.

Division of Nutritional Carcinogenesis, American Health Foundation,
Valhalla, New York 10595.

Nutr Cancer 2000;38(1):123-30

"Molecular mechanisms of cell cycle block by methionine restriction in
human prostate cancer cells."

Lu S, Epner DE.

Department of Medicine, Baylor College of Medicine and Veterans Affairs
Medical Center, Houston, TX 77030, USA.


"...methionine restriction-related life span extension is not a consequence of reduced energy intake. By feeding the methionine restricted diet to a variety of rat strains we determined that lowered methionine in the diet prolonged life in strains that have differing pathological profiles in aging, indicating that this intervention acts by altering the rate of aging, not by correcting some single defect in a single strain."

Zimmerman, JA et al. Nutritional control of aging.
Exp Gerontol 2003 Jan;38(1-2):47-52


so while restriction of particular amino acids, and thus the restriction of animal protein would appear to have benefit, it is still questionable whether or not the same health and longevity results the Okinawans enjoy is attainable by eating low calorie, but focus solely on protein and fat. I would think this attempt, given the low calorie constraints, would impair my ability to get optimal amounts of nutrition from vegetable matter. I think I will stick with the classic high carbohydrate, with a reliance on highly nutritious vegetable matter ..diet of the Okinawans.

Prometheus,

Thanks,
I've been interested in the subject of longevity through low bodyweight for several months (since the NY Times did a long feature on it.)

Of course, now there's the actual DOING it. Caloric restriction for me has always meant <2500 calories (but in my defense, I'm quite large.). Good plant food seems to be SO difficult for urban dwellers these days....especially in the dead of winter (with the "cotton" tomatoes.) I ijmagine I need to be thinking in terms of <2000 (or MUCH<) !

I agree, we need protein to replace (protein breakdown-recycling of amino acids); this is not a huge amount in a grown man. Using it for heat and energy is NOT what it was designed for...nature didn't throw amines and their nitrogen into every protein molecule simply to irritate the kidneys as acidic nitrogenous waste material.
And since the body can make fat from an excess of ANY food, how much of any animal's excess fat is useful to a human...it's hard to burn with an acidic residue (loosely called ketone bodies) and is usually the relatively safe storage location for many poisons that the body wants safely out of the way. Perhaps we might not NEED an animals stored poisons.

Zip, I agree with you that we do not, atleast as adults, need animal proteins, and even proteins in nuts and seeds have drawbacks. Different people choose different levels of caloric restriction. Personally, I restrict 40% of my daily recommended calories for my body weight. I'm female. My weight is 115. The ideal weight for my height is 120-125 and so my target weight is between 113-115. However, everyone's metabolism is different, so we try not to use weight as the measure for our restriction. Further some people need more or less calories depending on metabolism and level of activity so restriction is relative and it is very individualized. You are right that good plants are hard to come by! I am an urban dweller myself, but do not plan to be for long.

Prometheus, your postings sparked some interests in me on the ideas and benefits of CRON. So, I went and started doing some research and looking it up a bit :) . What I was curious about is the "weight" issue. Most information I checked out suggested that a person's target weight was about 15-20% below recommended weight. Now here is where my curiosities come in :) ... Now, say a person is taking in the "recommended amount of calories" for following CRON, and falls into a 20-30% below recommended weight...yet still maintains perfectly normal blood tests and feels/displays a level of healthiness. If they increased calories to gain/maintain a higher weight...would they then not achieve the benefits of this plan (since it is calorie restriction), and if everything checked out normal with their body..yet they were at a lower weight than their target weight would it still be okay? I was reading a few personal websites about others practing CRON who were about 22-27% below the "recommended" weight, and they were fine. Another question of mine is could this work for somebody who is a bit more active? (Also why I am wondering about the lower weight..simply because if your active you may need more calories....or your weight may get below that 20% target...but level off and remain there with your body working fine) Now my question is...did any of that make sense? :D lol, just a few questions of curiosity, sorry if they seem slightly "stupid" or "common sense" type questions, sometimes I just need things explained to me and outlined step by step lol. Thanks again for all of the help and information :) .

Meagan,

It is precisely this that we don't rely on weight to determine restriction. In certain lab studies mice who weighed a bit more despite being on the same caloric restriction diet ended up living longer than mice who became more lean, however they all lived longer than controls. This could have something to do with each body's unique ability to conserve and store energy. I think anything under your target weight should make you suspecious of starvation and therefore become more keenly aware of the amount of protein/fat/nutrients you are taking in, though it may just be a factor of your body's metabolism. It is very very important to moniter and get your blood tested on a CR program. Amount of activity is another good point you bring up, and it actually melts into some of the risks of CR. I hope I explain this right. In CR lab studies, mice who excercised but were not calorically restricted lived longer than mice who did not exercise and were not calorically restricted, but those mice who had the least activity and were calorically restricted lived the longest, longer than mice who were allowed to exercise and were calorically restricted. However, all calorically restricted mice lived longer than the non-calorically restricted mice.

One of the risks of CR is too much activity, which you would think would be a no brainer, but actually it isn't. In lab studies, CR mice, given free reign of a wheel, will run themselves to death. CR produces a desire, or a need to increase activity, a false sense of energy, and CR practioners can really go overboard, not get enough sleep, etc (Semi-Starvation Induced Hyperactivity, SIH). It is important for me, and CR practitioners to remind ourselves to be consciously aware of our activity, and consciously tell ourselves to slow down if no one else does. Meditation practices, and monk-like lifestyles are useful for this.

Thanks for explaining things to me Prometheus :) One of the reasons I was curious about all of it was because I do think it is such a fascinating topic and would love to practice it myself. Although, I already have to take in a pretty high amount of calories to maintain my weight (which is below "normal", but not terribly low below normal or anything like that), plus my days are not extremely active, but I do a fair amount of walking/cleaning/dance (classes and on my own time) etc. which keeps me busy (and on my feet) all day long. While reading some personal journals about the subject I came across a few people who also did a fair amount of exercise, yet their weights were slightly below the target weight. I wouldn't want to attempt anything and put my health in danger...so I'll just stick to what I'm doing now :) Thanks again! Take care!

Seriously Meagan you are right on with that. If my level of activity were greater I would not do it either. A lot of these people online with their personal homepages practicing "CR" do not know what they are getting themselves into. Sometimes people use CR as a front for eating disorders (preoccupation or more emphasis on weight is a hint). Read from the CR Society or read Dr. Walford's books. Dean Pomerleau gave a lecture at one of the annual CR Society conferences on the risks and Psychological effects of CR. You can get the transcript if you are interested.

Most of it is uncharted territory. We don't know that the beneficial effects of longevity apply to humans (likewise we don't know what a lot of the long term physical/psychological effects could be). CR is only a means to an end. Taken to extremes or practiced without caution may result in a person losing his/her life in order to save it. It defeats the purpose. It is better to have a nutrient rich, healthy, non-CR diet than try to do CR with additional risks (activity level, caloric needs, etc).