37 replies to this topic

[Brett Black]

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

They were developed, as far as I understand it, to calculate the relationship of steady state caloric intake to steady state bodyweight(and vice versa.) The endpoint of conventional caloric restriction diets meets both of these qualifications.

Very little in medicine was developed with a concurrent CR diet in place. Does this mean those on CR "can't use"(as you put) any medical knowledge?

Edited by Brett Black, 10 June 2011 - 12:54 AM.

[Brett Black]

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.

It may be that those who accurately gauge their own calorie intakes are the extreme outliers; which could explain a lot of what you've said here.....

How did you, and for how long, did you measure your calorie intake and weight?

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 don't have much trust in "everybodies" ability to accurately and objectively quantify much of their personal behaviour, including in the often pathologically biased areas of dieting, food intake and bodyweight. The fact that you use the anecdotal experience of the masses to try to support your argument sets off alarm bells for me.

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.

Whether or not long-term caloric restriction leads to increased metabolic efficiency is an interesting and maybe still unsettled issue. I personally haven't studied it enough to feel confident in commenting too much about it.

The thread-starter said they had a BMI of 20.1, didn't want to drop below a final BMI of 18, and was discussing a CR level of 33%. The Mifflin-St Jeor equations suggest no more than about 5% calorie restriction is possible, that leaves around 30% unaccounted for. Could increased metabolic efficiency from CR account for the missing ~30%? I'm doubtful.

It would be great if increased metabolic efficiency were significant, and might even convince me to give serious CR a shot(a higher viable restriction level would be expected to lead to greater life extension), but so far I'm unconvinced.

Here's an interesting post about some of these issues by Michael Rae(who seems to believe that the evidence suggests that if there are any such effects they are transitory):

"Basal Metabolic Rate (BMR) as a biomarker for Calorie Restriction (CR)"
http://www.crsociety...0938#msg-180938

[hivemind]

Low IGF-1 and low testosterone make you look older. Both are reduced on a CR-diet. CR lowers your libido too.

Edited by Trip, 11 June 2011 - 08:26 PM.

[The Immortalist]

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.

lol it's ok for me, I do bodybuilding.

[scottknl]

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

They were developed, as far as I understand it, to calculate the relationship of steady state caloric intake to steady state bodyweight(and vice versa.) The endpoint of conventional caloric restriction diets meets both of these qualifications.

Very little in medicine was developed with a concurrent CR diet in place. Does this mean those on CR "can't use"(as you put) any medical knowledge?

This thread explains why you shouldn't use those equations to apply to CR individuals:
http://www.crsociety...ad.php?2,205816

The final post in that thread contains this:

The caution in the use of the equations is clearly stated in the
conclusion of the referenced paper:
www.ncbi.nlm.nih.gov --edit correct URL
"The Expert Panel advises clinical judgment regarding when to accept
estimated RMR using predictive equations in any given individual.
Indirect calorimetry may be an important tool when, in the judgment
of the clinician, the predictive methods fail an individual in a
clinically relevant way. For members of groups that are greatly
underrepresented by existing validation studies of predictive equations,
a high level of suspicion regarding the accuracy of the equations
is warranted."

The CR calculator DOES NOT apply the MSJ equation to underweight
individuals, CRed individuals, or to any individuals at all.
The CR calculator uses the MSJ equation ONLY to calculate the
energy requirements of a control in the middle of the normal BMI range
which should generally produce acceptable results for the purpose of
being used as reference to determine the percentage of caloric restriction.

Edited by scottknl, 15 June 2011 - 08:38 PM.

[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!

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.

You don't get it. A CR diet is more than just cutting calories. If a person is cutting calories and is not getting adequate nutrients, amino's and vitamins/minerals, it is a completely different dietary schematic than someone who is practicing nutrient dense caloric restrictive dieting. People who practice CR diets for health reasons generally do so with a mind toward meeting the needs of all markers. This often entails the use of a crono-meter to gauge possible deficiencies, which affords a completely different outcome than someone simply on a calorie deficit. So your reference is still quite irrelevant. BMI is not the main determinant of age perception. Perhaps in people who have eaten unhealthy all their lives and then went on a calorie deficit it could be so. But for healthy dieters who have maintained a lean body most of their adult lives, I think not. Unless they're sun junkies.

[Brett Black]

You don't get it. A CR diet is more than just cutting calories. If a person is cutting calories and is not getting adequate nutrients, amino's and vitamins/minerals, it is a completely different dietary schematic than someone who is practicing nutrient dense caloric restrictive dieting. People who practice CR diets for health reasons generally do so with a mind toward meeting the needs of all markers. This often entails the use of a crono-meter to gauge possible deficiencies, which affords a completely different outcome than someone simply on a calorie deficit. So your reference is still quite irrelevant.

No two humans or diets are likely to be exactly the same in either CR people or any other population. You can pick out any number of variables and find differences and similarities e.g. CR men and ad-lib men are both male, so more alike in this variable than CR men and CR women. What (much) research attempts to do is define the relevant variables and relate them to generalizable results.

In the study I referred to, BMI is the variable, and its relationship to perceived age is the generalized result. We know that BMI is a variable shared by CR practitioners.

Do you know of any studies that disprove this general relationship between BMI and perceived age in CR'ed humans?

BMI is not the main determinant of age perception. Perhaps in people who have eaten unhealthy all their lives and then went on a calorie deficit it could be so. But for healthy dieters who have maintained a lean body most of their adult lives, I think not.

Do you know of any studies that show this?

Edited by Brett Black, 17 June 2011 - 02:29 AM.

[TheFountain]

You don't get it. A CR diet is more than just cutting calories. If a person is cutting calories and is not getting adequate nutrients, amino's and vitamins/minerals, it is a completely different dietary schematic than someone who is practicing nutrient dense caloric restrictive dieting. People who practice CR diets for health reasons generally do so with a mind toward meeting the needs of all markers. This often entails the use of a crono-meter to gauge possible deficiencies, which affords a completely different outcome than someone simply on a calorie deficit. So your reference is still quite irrelevant.

No two humans or diets are likely to be exactly the same in either CR people or any other population. You can pick out any number of variables and find differences and similarities e.g. CR men and ad-lib men are both male, so more alike in this variable than CR men and CR women. What (much) research attempts to do is define the relevant variables and relate them to generalizable results.

In the study I referred to, BMI is the variable, and its relationship to perceived age is the generalized result. We know that BMI is a variable shared by CR practitioners.

Do you know of any studies that disprove this general relationship between BMI and perceived age in CR'ed humans?

BMI is not the main determinant of age perception. Perhaps in people who have eaten unhealthy all their lives and then went on a calorie deficit it could be so. But for healthy dieters who have maintained a lean body most of their adult lives, I think not.

Do you know of any studies that show this?

You have to first show a study that uses a model based on people who specifically are on CR diets from a young age, and prove that BMI influences perceived age in these people. Otherwise CR practitioners here will shoo that other study away.

There is more to skin suppleness than bodyfat levels. If that were not the case then young men with bodyfat levels of 8% and low BMI would look like old men. There is a mechanism in CR, metabolic and otherwise, where the activation of certain genes may exhibit a prolonged anti-aging effect, independent of body mass index.

People simply on calorie deficits without proper nutrient intake, and who started at a later age, would not show a reversal of the effects of their previously damaging diets. This is more than likely the case in that study you keep referring to, as if it actually matters in this discussion, and this again is why that study is irrelevant.