37 replies to this topic

[Live Fast Die Pretty]

Hi!
I'm skeptical about CR.. I want to believe it but .... my intuitive feeling is that the benefits will be too small to be worth the effort. Already, we know that adult onset CR is not as effective. I'm in my early 20s.

Some things I have questions about:
1. I'm not a scientist but isn't it possible that lab studies have flaws?
-the ad libitum animals may be eating artifically high amounts of food since they have access to food whenever they want. this means the "calorie restricted" animals aren't restricted at all.
-the lab environment is sterile. for humans in real life, there are many pathogens in the environment, viruses cause 70% of DNA damage. we are exposed to a number of mutagens that lab animals are not exposed to such as ultraviolet raditation, chemicals, etc. will caloric restriction still work in a real life environment?
-the food given to lab animals is the same everymeal, everyday but we eat a huge variety of different foods, fruits, vegetables, nuts, seeds, legumes, oils, fish, meat, eggs, dairy, alcohol, etc not to mention those pesticdes, additives, preservatives, will CR still work in a varied diet?
-i wonder whether the macronutrient ratio makes any difference? there is not much research on this. some people say carbs is bad (blood glcuose for creating AGE's), some say protein is bad (dna damage caused by deamination of excess protein ), fat also gets a bad name. what is there left to eat?
-the lab animals were in cages (not very nice ) but this means they don't get much physical activity. its no fun being sedentary. we have an active life, we probably spend 500 claories a day in extra to basal metabolism in activities, many people also exercise... will caloric restriction still work in people who are active?

2. the okinawans have a calorically restricted diet but their life expectancy is only 78 (male) and 86 (female) compared to a country with a typical western diet such as australia where the life expectancy is 79 (male) and 84 (female). there isn't really a difference.

3. some studies show a higher mortality risk for being underweight. is this really just due to counfounding effects of smoking and illness? why do the word health organization have a bmi of 18.5 - 25 as being healthy?

questions specific for women:
-any meaningful level of CR will lower bodyfat to a level where periods will stop. i'm worried about estrogen for my bones in the future
-i will have to go back to a normal diet when i get pregnant. this will be a shock to my body. yo-yo weight fluctuation increases mortality. i will have to start and stop CR everytime i want to have a child (i want to have at least 3 children )
-studies show that men find bmi below 18 to be unattractive. my bmi is 20.1 right now without CR. i don't want to go below 18 but with 33% CR i dont know what my weight will be

caloric restriciton takes a huge amount of time and effort (1 hour plus a day weighing& measuring food, reading food labels, counting and recorrding calories which i can spend doing more fun stuff). for me calorie restriction would have to extend life by more than the amount of time i spend on it, 1 hour a day = 365 hrs a year, over the next 60 years = 22,000 hours = 3 years. so calorie restriction would have to extend life more than 3 years to be worth the time i spend on it.

well i dont really care about dying. i dont want to be immortal. my children will carry on my genes. but i do want to stay young and pretty forever. i wouldnt mind dying at 80 like everyone else, as long as i still look 20 years old! maybe plastic surgery is the answer for me , not caloric restriction

please tell me if i broke any of the forum rules or asked any dumb questions. i will change it.. thank you for reading this

[JLL]

There was a big thread about this a while ago, suggesting that extrapolating from the rodent studies, CR would give a human maybe 5 extra years.

Personally, I don't think CR is worth it in humans, but if you want to maximize your chances of making it to longevity escape velocity then I can see the reasoning. I just think the negatives vastly outweigh the benefits.

[Brett Black]

Hi!
I'm skeptical about CR.. I want to believe it but .... my intuitive feeling is that the benefits will be too small to be worth the effort. Already, we know that adult onset CR is not as effective. I'm in my early 20s.

I think there's good reason to be very skeptical about human CR. Here's a thread I started that shows that based on projections from CR in rodents, the severest(anorexia-weight) adult-onset CR in humans will only give 4-8 years of extra life:

http://www.longecity...-to-human-life/

Some things I have questions about:
1. I'm not a scientist but isn't it possible that lab studies have flaws?
-the ad libitum animals may be eating artifically high amounts of food since they have access to food whenever they want. this means the "calorie restricted" animals aren't restricted at all.

Some recent CR studies try to account for gross gluttony by reducing the "ad libitum" rodent group to ~90% calories of actual all-you-can-eat real ad-lib. Even with this restriction though, the CR'ed rodents can still handle a massive ~50% reduction in calories compared to these partially restricted "Ad Lib" controls. In comparison, no human being could survive a longterm 50% food restriction unless that restriction was imposed from an initially obese ad-libitum state. I think there may still be reasonable grounds to believe that even the partially restricted ad-libs are overeating.

-the lab environment is sterile. for humans in real life, there are many pathogens in the environment, viruses cause 70% of DNA damage. we are exposed to a number of mutagens that lab animals are not exposed to such as ultraviolet raditation, chemicals, etc. will caloric restriction still work in a real life environment?

This is a real concern. It has been shown that CR'ed mice die from a flu infection when ad-libitum do not:
"Malnutrition and Energy Restriction Differentially Affect Viral Immunity"
http://jn.nutrition....136/5/1141.full

Can you point me to the source(s) suggesting that viruses cause 70% of DNA damage - sounds interesting.

-the food given to lab animals is the same everymeal, everyday but we eat a huge variety of different foods, fruits, vegetables, nuts, seeds, legumes, oils, fish, meat, eggs, dairy, alcohol, etc not to mention those pesticdes, additives, preservatives, will CR still work in a varied diet?

Impossible to say. Human CR is an experiment. There are so many potential variables involved. The underlying mechanism(s) for CRs effects in rodents has still yet to be agreed upon/discovered. The recent studies on dietary advanced glycation endproducts shows that even things like food preparation and processing may have very significant effects independent and/or intermixed with CR.

i wonder whether the macronutrient ratio makes any difference? there is not much research on this. some people say carbs is bad (blood glcuose for creating AGE's), some say protein is bad (dna damage caused by deamination of excess protein ), fat also gets a bad name. what is there left to eat?

Michael Rae, one of the most prominent and influential human practitioners of CR ate, and very strongly recommended, high protein intake CR for years. Recently he and many others have reversed their position, and gone for a much lower protein intake(RDA levels.) This was(as I understand it), largely the result of studies that showed that IGF-1 was boosted in high-protein human CR, but reduced IGF-1 is considered a hallmark of successful CR in animal studies and seems to be connected to slowed aging. Did Michael and Co. completely undermine their CR efforts for an entire decade because of the high protein? Who knows. But if someone as knowledgeable in CR as Michael can make such apparently fundamental changes in CR practice, is it worth risking years of effort that could potentially end up being wasted when new evidence appears?

the lab animals were in cages (not very nice ) but this means they don't get much physical activity. its no fun being sedentary. we have an active life, we probably spend 500 claories a day in extra to basal metabolism in activities, many people also exercise... will caloric restriction still work in people who are active?

Currently the most popular and favored principle believed responsible for inducing the lifespan-extending effects of CR is, you guessed it: reduced calorie intake. Exercise burns calories, which, in order to maintain the same weight, all things else being equal, requires increased calorie intake. Exercise(calorie burning) is thus diametrically opposed to the first principle of CR.

the okinawans have a calorically restricted diet but their life expectancy is only 78 (male) and 86 (female) compared to a country with a typical western diet such as australia where the life expectancy is 79 (male) and 84 (female). there isn't really a difference.

Absolutely agree. For all the talk about them, the data I have seen on the Okinawans is, frankly, pathetic.

some studies show a higher mortality risk for being underweight. is this really just due to counfounding effects of smoking and illness? why do the word health organization have a bmi of 18.5 - 25 as being healthy?

I'd suggest it's because this is what the data and experts tell them is the most healthy BMI for the average person. If CR(and the related lower BMI) is proven healthy and effective in a large enough number of humans they may revise their recommendations.

-i will have to go back to a normal diet when i get pregnant. this will be a shock to my body. yo-yo weight fluctuation increases mortality. i will have to start and stop CR everytime i want to have a child (i want to have at least 3 children )

I've seen conflicting results for studies on yo-yo weight fluctuations and mortality.

-studies show that men find bmi below 18 to be unattractive. my bmi is 20.1 right now without CR. i don't want to go below 18 but with 33% CR i dont know what my weight will be

There's no way in hell you'd be able to do 33% CR from you current BMI, you'd simply die of starvation. With your starting BMI of 20.1, I doubt you could do more than around 5% CR without falling below 18 BMI. It's when you start looking at these numbers that you really get an understanding of how little CR healthy-weight humans can handle.

Go to the following website and enter your age, height and expected weight pre and post CR to get a calculated CR level: http://www.scientifi...alth/cron2.html

Based on rodent studies, CR started in early adulthood results in less than 1/2 the percent of lifespan increase as compared to the percent of CR. So if you can manage 5% CR then the projections suggest no more than 2.5% increase in lifespan.

Your BMI of ~20 is already within the range of many serious CR practioners.

well i dont really care about dying. i dont want to be immortal. my children will carry on my genes. but i do want to stay young and pretty forever. i wouldnt mind dying at 80 like everyone else, as long as i still look 20 years old! maybe plastic surgery is the answer for me , not caloric restriction

My own observations suggest that increasing thinness tends to increase the perceived visual age of a person. Maybe the subcutaneous fat tends to fill in wrinkles and smooth out the skin? Here's a study that backs up my personal observations:

"Longevity and gray hair, baldness, facial wrinkles, and arcus senilis in 13,000 men and women: the Copenhagen City Heart Study"
http://www.ncbi.nlm..../pubmed/9754140

from the study:

"Perceived age was influenced negatively by exposure to sun, smoking, and low body mass index (BMI)"

Maybe CR is the opposite of what you'd want to do for youthful looks?

I also wonder if having children might affect your youthful looks negatively.

Edited by Brett Black, 08 May 2011 - 03:13 PM.

[scottknl]

The biggest benefit from CR is your increased health. You're simply never ill with coughs, colds, flu or any aches or pains. Pretty but sick doesn't sound like a good trade off to me. If you get some extra years, then great; it's a bonus! You really get extra years because you don't spend time being sick and unable to participate in life. When you throw in almost total elimination of heart attack, stroke, and diabetes along with 50 - 67 % reduction in cancer, there's some real benefit from doing CR.

Other benefits from CR are better mood, good digestion, good energy for day to day activities.

The other drawbacks for CR are reduced energy requiring endurance, gaunt appearance and the social aspects. Low libido has been reported for some men, but increased libido for some women.

The older you become the more you appreciate the health aspects of CR. If you've ever lost your good health for some time, you know what I mean.

[Matt]

wow this topic has been discussed a lot, you should check out the other threads around here. Although I'm not as optimistic about CR as I was before, I still think it offers huge amount of protection from diseases and is worth the effort. In terms of lifespan extension. even without CR there are populations around the world living to their mid - late 80's without CR. Seventh Day Adventists average lifespan of 88 years (bmi 25-26) without CR, just eating quite healthy. Maybe CR can add 10-20 years if started around 18-30. All just speculative of course. As for CR making you appear older, not in my experience... but I'm just one person... I've been CR'd since 18 and I'm now almost 27 and people tend to think of me as being around 17-18 years of age. hehe. :-) Decide for yourself if you think I'm approaching 30 http://www.facebook....9c&id=635673153

lol

Staying at a low normal weight from a young age is more likely to preserve youthful looks rather than trying to lose huge amount of weight when you're older.

Edited by Matt, 08 May 2011 - 06:56 PM.

[Forever21]

Like the OP, I'm not that interested in life extension. I'm more interested in looking young. I'd take 60 years of life as long as you make me look 21 on my 60th birthday.

So when you say CR might only give you just 4-5 years extra life, that really doesn't discourage me because I just don't care. In fact, even if CR decrease my life for up to 20 years, I'd still do it if that means I get to look like 21 years old on my 60th birthday.

If I'm going to list what my driving motivation for doing CR, I wouldn't even put life extension on 2nd or 3rd spot. It would be more like this

1. LOOK YOUNG
2. Being in "control" (like a hobby, travel, car collecting, toys)
3. Eventually w/ CR, you get good at it, you learn, knowledge builds complexity which then breeds aesthetic & awe-inspiring joy

4. Possible health benefits
5. Possible longevity benefits

I'd still do it if it doesn't increase life provided that I look young throughout on my short life. Give me 60 years looking like a college freshman over 120 years looking like Mark Sisson.


So my concern is NOT whether CR increases your lifespan but whether CR can help make you look young as long as possible?


.

http://www.youtube.com/watch?v=TElbEVlYZo4

Edited by Forever21, 08 May 2011 - 06:18 PM.

[platypus]

2. Being in "control" (like a hobby, travel, car collecting, toys)

Isn't that a "benefit" of anorexia too? Flirting with an eating disorder is NOT a good reason to do CR, IMO.

[Forever21]

2. Being in "control" (like a hobby, travel, car collecting, toys)

Isn't that a "benefit" of anorexia too? Flirting with an eating disorder is NOT a good reason to do CR, IMO.

or studying hard to go to harvard & be a nobel prize recipient,
or studying hard to join al qaeda & be the next bin laden
what's your point?

[platypus]

2. Being in "control" (like a hobby, travel, car collecting, toys)

Isn't that a "benefit" of anorexia too? Flirting with an eating disorder is NOT a good reason to do CR, IMO.

or studying hard to go to harvard & be a nobel prize recipient,
or studying hard to join al qaeda & be the next bin laden
what's your point?

My point is right there, if CR gives you a feeling of "control" you might be flirting with an eating disorder, which can be very dangerous. What's your point? Anorexia is a bad reason for joining al qaeda???

[Forever21]

I see. You got nothing to worry. I'm speaking more in terms of Muensterberger POV. That maintaining a sense of balance of control and completion. The object can be a stamp, baseball or a day CRON sheet. Focus and basic interest in the topic brings this sense of control.

[Saintor]

It is 100% worth it. It changed my life, really.

Better health and vitality overall.
Compliments for how improved my look is.
When you age, your metabolism tends to slow down; between 25 and 45, it does so by like 6% and continues. CR is a great countermeasure for this.
Finally but not the least, CR counters cardiac problems (both my brother and mother had strokes, my father arrhythmia), diabete, BP, and even cancer! You know what is the very first recommendation against cancer? Following a large compilation of thousands of studies in 2007;

http://www.aicr.org/...tions_01_weight
1. Be as lean as possible without becoming underweight.

If it isn't a case for CR, I don't know what it is. Of course, you can be slim for the wrong reasons, but this is not what is suggested here.

Finally I have a cheating day every 2 weeks, and I couldn't do CR without it. Still losing weight and feeling awesome.

Edited by Saintor, 10 May 2011 - 01:10 AM.

[The Immortalist]

Like the OP, I'm not that interested in life extension. I'm more interested in looking young. I'd take 60 years of life as long as you make me look 21 on my 60th birthday.

So when you say CR might only give you just 4-5 years extra life, that really doesn't discourage me because I just don't care. In fact, even if CR decrease my life for up to 20 years, I'd still do it if that means I get to look like 21 years old on my 60th birthday.

If I'm going to list what my driving motivation for doing CR, I wouldn't even put life extension on 2nd or 3rd spot. It would be more like this

1. LOOK YOUNG
2. Being in "control" (like a hobby, travel, car collecting, toys)
3. Eventually w/ CR, you get good at it, you learn, knowledge builds complexity which then breeds aesthetic & awe-inspiring joy

4. Possible health benefits
5. Possible longevity benefits

Your reasoning for doing CR is very strange to be honest.

Like the OP, I'm not that interested in life extension. I'm more interested in looking young. I'd take 60 years of life as long as you make me look 21 on my 60th birthday.

It's the exact same reason I do natural bodybuilding. I'd rather live 90 years jacked then 110 years skinny. Bodybuilding can do the same. Natural Bodybuilding keeps your body looking young (except the face maybe but who cares about the face? looking old doesn't look that bad, it adds character to your face).
74 year old bodybuilder:

If I'm going to list what my driving motivation for doing CR, I wouldn't even put life extension on 2nd or 3rd spot. It would be more like this

If I'm going to list my driving motivation for doing natural bodybuilding, I wouldn't even put living strong into old age into the 2nd or 3rd spot.

It would be more like this

1. LOOK YOUNG
2. Being in "control" (like a hobby, travel, car collecting, toys)
3. Eventually w/ CR, you get good at it, you learn, knowledge builds complexity which then breeds aesthetic & awe-inspiring joy

4. Possible health benefits
5. Possible longevity benefits

1. Can achieve with natural bodybuilding
2. Can be achieved with natural bodybuilding
3. You can achieve with natural bodybuilding
4. You can achieve health benefits with natural bodybuilding like staving off osteoporsis, keeping muscle mass,
keeping your skin looking young and decreasing the chance of dying from injury.
5. While natural bodybuilding and working out with weights can't increase your max lifespan it can decrease the morbidity of your later years significantly.

I just don't get it. Why do CR unless your doing it to increase your max lifespan?

[Forever21]

^^ Considering your reputation for being a troll in previous thread, note that I didn't read a word of what you've said. Ignored.

[The Immortalist]

^^ Considering your reputation for being a troll in previous thread, note that I didn't read a word of what you've said. Ignored.

Thanks mate. No hard feelings eh?

Edited by The Immortalist, 10 May 2011 - 04:39 PM.

[Saintor]

1. Can achieve with natural bodybuilding
2. Can be achieved with natural bodybuilding
3. You can achieve with natural bodybuilding

CR is much more than merely being lean and no, natural bodybuilding can't achieve the known CR benefits. Physical trainers will support that if you don't eat enough to support your weight, you'll eventually die. This is definitely proven false. CR triggers something unexpected and factually supported by repetitive science for decades; overall organisms live longer and healthier. Reason is at the physiological, biochemical and even molecular level. Big muscles won't bring you at this level. Not enough.

Here is a paper from Oxford University.

See the summary at the last page here.
http://carcin.oxford...7.full.pdf html

[The Immortalist]

Natural bodybuilding can't achieve the known CR benefits.

Did I say that? I only said it can achieve very similar benefits Forever21 listed as his reasons for doing CR. The only reason I see to do CR is to try to live longer than your could have without it.

[Saintor]

The only reason I see to do CR is to try to live longer than your could have without it.

Living longer is just an icing on the cake if it happens. Not my motivator. CR is known to prevent to an extent serious diseases over the long run.

Interesting article here
http://www.scienceda...80514064921.htm

Instead the study suggests that caloric restriction creates beneficial changes in the body’s hormone levels which exercise does not

[TheFountain]

I have a feeling the okinawan life expectancy numbers have been skewed in recent years. The fact that many of the natives have likely adopted a western style diet in the past couple of decades (thanks to the increased introduction of fast food establishments) begs the question, what happened to okinawa? Either the numbers are skewed, the diet changed or both.

Edited by TheFountain, 11 May 2011 - 08:08 AM.

[TheFountain]

"Longevity and gray hair, baldness, facial wrinkles, and arcus senilis in 13,000 men and women: the Copenhagen City Heart Study"
http://www.ncbi.nlm..../pubmed/9754140

from the study:
Quote

"Perceived age was influenced negatively by exposure to sun, smoking, and low body mass index (BMI)"

Irrelevant since these people were not specifically practicing CR!

[TheSeeker]

In comparison, no human being could survive a longterm 50% food restriction unless that restriction was imposed from an initially obese ad-libitum state.

This is plain false. The body is able to adapt to low calorie intake and the dramatic metabolic changes can shift anabolic and catabolic processes where a new steady state is reached.
A much bigger problem than mere calorie restriction is rather the optimal micronutrient intake. When on substantial calorie deficit (especially when combined with vegan diet or with methionine restriction), you will have to take particular care of critical substances such as B12, folate, methyldonors such as choline / betaine etc. People who don't do this often get sick. Not to mentione sulfur-amino acids such as l-carnitine or taurine the generation of which may get significantly hampered when on a low protein/low-methionine diet.
Accounting for these (and other) ciritcal factors, a substantial caloric restriction (even if it is 50%) will NOT lead to a linear weight loss but to a new steady state and definitely not to death. I am 188 cm tall and 70 kg of weight and I do perfectly live with around 1000-1200 kcal/d. (My theoretical daily calory intake should be almost double in order to not die???)

i wonder whether the macronutrient ratio makes any difference? there is not much research on this. some people say carbs is bad (blood glcuose for creating AGE's), some say protein is bad (dna damage caused by deamination of excess protein ), fat also gets a bad name. what is there left to eat?

Yes it makes a huge difference. Isolated restriction of carbohydrates did have no effect on LE, nor did isolated restriction of fats. Surprisingly, protein restriction did have an effect, and more specifically, methionine restriction extended life-span by 30-40% in rodents.

Currently the most popular and favored principle believed responsible for inducing the lifespan-extending effects of CR is, you guessed it: reduced calorie intake. Exercise burns calories, which, in order to maintain the same weight, all things else being equal, requires increased calorie intake. Exercise(calorie burning) is thus diametrically opposed to the first principle of CR.

LOL, this statement is blatantly ignoring the complex interactions of physical activity and calorie intake. physical activity per se has a cornucopium of anti-degenerative effects and I think it is safe to say that moderate levels of exercise will favorably complement a healthy CR-based lifestyle.

There's no way in hell you'd be able to do 33% CR from you current BMI, you'd simply die of starvation.

Utter nonsense, completely ignoring the huge adaptational capabilities of human metabolism.

[Brett Black]

In comparison, no human being could survive a longterm 50% food restriction unless that restriction was imposed from an initially obese ad-libitum state.

This is plain false.

Upon what basis/evidence do you make that claim?

The Mifflin-St Jeor metabolic rate equations are currently considered to give the most accurate peer-reviewed calculations available, as far as I'm aware(1). These are what I based my claim that 50% food restriction is simply not going to be possible for anyone but the obese.

Here is a page with a Mifflin-St Jeor calculator: http://www.scientifi...alth/cron1.html

Here are the results of these equations for a 30 year old male of 177cm height at various weights and the subsequent basal metabolic rates:

Weight=115kg, BMI=36.7, BMR = 2111 kcal per day, relative BMR=123%
Weight=105kg, BMI=33.5, BMR = 2011 kcal per day, relative BMR=118%
Weight=95kg, BMI=30.3, BMR = 1911 kcal per day, relative BMR=112%
Weight=85kg, BMI=27.1, BMR = 1811 kcal per day, relative BMR=105%
Weight=75kg, BMI=23.9, BMR = 1711 kcal per day, relative BMR=100%(healthy BMI "set point" / reference BMR)
Weight=65kg, BMI=20.7, BMR = 1611 kcal per day, relative BMR=94%
Weight=55kg, BMI=17.6, BMR = 1511 kcal per day, relative BMR=88%
Weight=45kg, BMI=14.4, BMR = 1411 kcal per day, relative BMR=82%
Weight=35kg, BMI=11.2, BMR = 1311 kcal per day, relative BMR=77%

These calculations show that dropping weight from 115kg down to 35kg(which would lead to death) occurs when calories are cut(all things else being the same, e.g. exercise) by just 36%. Different gender, ages and heights give similar results.

A much bigger problem than mere calorie restriction is rather the optimal micronutrient intake. When on substantial calorie deficit (especially when combined with vegan diet or with methionine restriction), you will have to take particular care of critical substances such as B12, folate, methyldonors such as choline / betaine etc. People who don't do this often get sick. Not to mentione sulfur-amino acids such as l-carnitine or taurine the generation of which may get significantly hampered when on a low protein/low-methionine diet.

Accounting for these (and other) ciritcal factors, a substantial caloric restriction (even if it is 50%) will NOT lead to a linear weight loss but to a new steady state and definitely not to death.

I didn't say it would lead to a "linear" weight loss, and a "steady state" weight is not inherently in opposition to linear weight loss anyway. My point was that the theoretical steady state weight that could be sustained after a 50% cut in calories would be below the steady state weight necessary to continue living.

You haven't put forward any substantial evidence to back your position, seemingly just picking numbers out of the air. It makes me wonder what arbitrary percent of calories you believe could be survived. Could a person survive a 59% calorie reduction? How about a 65% calorie cut, or 79% or even 97% calorie cut?

I am 188 cm tall and 70 kg of weight and I do perfectly live with around 1000-1200 kcal/d. (My theoretical daily calory intake should be almost double in order to not die???)

If that's truly your height, weight and calorie intake you are far outside the norm as regards the Mifflin-St Jeor caculations. The other quite reasonable possibility, as far as I'm concerned, is that you haven't accurately gauged your calorie intake. In either case, I have been addressing relative calorie restriction(percentage differences), not absolute calorie intakes, which might reduce the impact of outliers. Also, the simple fact that I was referring to a 50% calorie reduction from an initial BMI <30, which is surely an extreme level, would, I'd expect, weed out even the most extreme outliers.

There's no way in hell you'd be able to do 33% CR from you current BMI, you'd simply die of starvation.

Utter nonsense, completely ignoring the huge adaptational capabilities of human metabolism.

Merely waving around "huge adaptional capabilities" without sufficient evidence doesn't do anything to support your claims.



REFERENCES

1. "Validation of several established equations for resting metabolic rate in obese and nonobese people" PMID: 2963943 http://www.ncbi.nlm....pubmed/12963943

Edited by Brett Black, 31 May 2011 - 11:45 AM.

[scottknl]

You can't use those equations for CR. They weren't developed with CR diets; only adlib.

[TheSeeker]

My point was that the theoretical steady state weight that could be sustained after a 50% cut in calories would be below the steady state weight necessary to continue living.

There's no way in hell you'd be able to do 33% CR from you current BMI, you'd simply die of starvation.

I do indeed have a slow metabolism ("softgainer") and I know numerous people with a similar type of metabolism who are on a CR anywhere in between 20-50% and everybody of them (myself included) have reached a new steady state (without further weight loss) that is far above and beyond your "35 kg" mark of death.

It is certainly true that people with a very different metabolism (e.g. people who are very lean even when eating a lot) may suffer from detrimental or even critical weight loss even while on a much more modest CR diet.
But I wouldn't consider myself and people I described above as extreme outliers either.

Merely waving around "huge adaptional capabilities" without sufficient evidence doesn't do anything to support your claims.

Everybody who has ever attempted to merely lose some weight can witness the tremendous increase of energy efficiency that comes along with CR.
I haven't searched systematically, but just from a simple 3-klick search here is the first reference I came across (which most likely isn't even the best one but just the first one I stumbled across) and which supports quite substantial adaptations of energy metabolism/energy expenditure during CR, thus making all those nice formulas you presented above totally unusable to predict weight loss from a given amount of CR.

Look here:


American Journal of Clinical Nutrition, Vol 49, 93-96, Copyright © 1989 by The American Society for Clinical Nutrition, Inc



--------------------------------------------------------------------------------

ORIGINAL RESEARCH COMMUNICATIONS


Sustained depression of the resting metabolic rate after massive weight loss
DL Elliot, L Goldberg, KS Kuehl and WM Bennett
Division of General Medicine, Oregon Health Sciences University, Portland.

To assess potential long-term effects of weight loss on resting metabolic rate (RMR), the RMRs of seven obese women were measured by indirect calorimetry before weight loss, during a protein-sparing modified fast, and for 2 mo while at a stable reduced weight. Body composition was also determined at each interval. RMR significantly decreased 22% (p less than 0.01) with initiation of the modified fast. RMR values during the modified fast and during the maintenance diet at stable reduced weight were not different and all were significantly lower than the prediet RMR. Loss of lean tissue could not account for the decrease because changes in RMR per fat-free mass paralleled the total RMR reduction. A sustained decrement in RMR accompanied weight loss and persisted for greater than or equal to 8 wk despite increased caloric consumption and body weight stabilization.

[Donnie]

I am 188 cm tall and 70 kg of weight and I do perfectly live with around 1000-1200 kcal/d. (My theoretical daily calory intake should be almost double in order to not die???)

Interesting. Would you care to post your diet on here? Would be nice to see a more extreme approach to CR. You must be close to ketosis? Also does this affect your libido more? Provided that you've tried a less radical version of CR.

I've been at 70 kg before at 186 cm tall and I didn't look that skinny. Do you feel skinny/bony?

I do indeed have a slow metabolism ("softgainer") and I know numerous people with a similar type of metabolism who are on a CR anywhere in between 20-50% and everybody of them (myself included) have reached a new steady state (without further weight loss) that is far above and beyond your "35 kg" mark of death.

Are you implying that you transformed into this slower metabolism or were you a softgainer even before and CR just added to that?

Edited by Donnie, 31 May 2011 - 05:41 PM.

[The Immortalist]

I eat over 4000 calories a day.

[Logan]

wow this topic has been discussed a lot, you should check out the other threads around here. Although I'm not as optimistic about CR as I was before, I still think it offers huge amount of protection from diseases and is worth the effort. In terms of lifespan extension. even without CR there are populations around the world living to their mid - late 80's without CR. Seventh Day Adventists average lifespan of 88 years (bmi 25-26) without CR, just eating quite healthy. Maybe CR can add 10-20 years if started around 18-30. All just speculative of course. As for CR making you appear older, not in my experience... but I'm just one person... I've been CR'd since 18 and I'm now almost 27 and people tend to think of me as being around 17-18 years of age. hehe. :-) Decide for yourself if you think I'm approaching 30 http://www.facebook....9c&id=635673153
http://www.facebook....53&l=d2e027b841 lol

Staying at a low normal weight from a young age is more likely to preserve youthful looks rather than trying to lose huge amount of weight when you're older.

I think keeping the calories fairly low and staying lean throughout youth will keep a young person looking young. The problem is when older people take part in moderate calorie restriction, they tend to have more sunken in faces and look older than their peers who are a more normal weight. I do think, if started early, moderate CR can help someone look younger at an older age, as long as enough volume and collagen is maintained.

[Logan]

I eat over 4000 calories a day.

Shit I think I do too. I'm going to have to figure out what my average daily caloric intake is. I do want to decrease it a bit. Believe it or not, exercise helps me control my bad night time eating habits. For me, if I don't exercise properly, I tend to indulge more.

[Guest]

To add to this discussion I going to restate my previous comment; adressing the metabolic and motivational issues:

http://www.longecity...post__p__419354


in principle a lot of the stuff you posted where already discussed "back" then. You might consider reading those ancient pieces from, ahem, a couple of month ago.

[Mind]

I am considering volunteering for the NYU CR study. I have dabbled with it in the past. My number one reason to do it is for the health benefits (although the "Cronies never get sick, never sneeze, never suffer from disease" line is mostly anecdotal, and unlikely to be true, the animal studies are substantial enough in my view). I am 40 so squeezing more health into my years is becoming more important.

A couple of the drawbacks are getting cold and scaling back athletic activities. Living in Wisconsin and doing CR is tough...I know from experience. It sucks being cold all the time. Also, I live a very active life, which would have to be scaled back. I ride bike to work 3 miles each way, then I go home and garden, maybe play a few games of high intensity basketball, on different days lift weights, jog several miles, walk a mile upstream against the current while fishing, etc... There is only so much a person can do while cutting 30 to 40% of calories from a diet.

[Brett Black]

"Longevity and gray hair, baldness, facial wrinkles, and arcus senilis in 13,000 men and women: the Copenhagen City Heart Study"
http://www.ncbi.nlm..../pubmed/9754140

from the study:
Quote

"Perceived age was influenced negatively by exposure to sun, smoking, and low body mass index (BMI)"

Irrelevant since these people were not specifically practicing CR!

The study wasn't investigating people on CR specifically, but that doesn't make it irrelevant. It's relevant because CR also reduces BMI, and BMI was part of this study. Is this study completely 100% perfectly relevant(or even greatly relevant)? No. Only engaging in CR on an individual person-by-person basis will be completely 100% perfectly relevant to any particular individual.

Generalizing from studies in other humans is one of the most fundamental modern methods for trying to ascertain the expected effects of a particular intervention on any particular individual. This is the only study that I know of that attempted to correlate one known and obvious visually-related aspect of CR(reduction in BMI/weight) with subjectively perceived age, which is what the original poster was interested in. I think it may in fact be about the most singly relevant study available at the current time linking these particular issues.

Edited by Brett Black, 10 June 2011 - 12:41 AM.