Re: Aging, Adiposity, and Calorie Restriction

[Guest guest]

We still remember the discussions of the " gray zone " , where CR proved

to have some detrimental psychological effects when the percent of

body fat got too low.

Now, Dr. Luigi Fontana has taken a stand on the side of caution with

his conclusion regarding CR and low body fat:

" In addition, it is possible that even moderate calorie restriction

may be harmful in specific patient populations, such as lean persons

who have minimal amounts of body fat. "

Tony

>

> Aging, Adiposity, and Calorie Restriction

> Luigi Fontana, MD, PhD

> Klein, MD

>

> Context Excessive calorie intake and subsequent obesity increases

the risk of developing

> chronic disease and decreases life expectancy. In rodent models,

calorie restriction

> with adequate nutrient intake decreases the risk of developing

chronic disease

> and extends maximum life span.

>

> Objective To evaluate the physiological and clinical implications

of calorie restriction

> with adequate nutrient intake.

>

> Evidence Acquisition Search of PubMed (1966-December 2006) using

terms encompassing

> various aspects of calorie restriction, dietary restriction,

aging, longevity,

> life span, adiposity, and obesity; hand search of journals that

focus on obesity, geriatrics,

> or aging; and search of reference lists of pertinent research and

review articles

> and books. Reviewed reports (both basic science and clinical)

included epidemiologic

> studies, case-control studies, and randomized controlled trials,

with quality of data assessed

> by taking into account publication in a peer-reviewed journal,

number of animals

> or individuals studied, objectivity of measurements, and

techniques used to minimize

> bias.

>

> Evidence Synthesis It is not known whether calorie restriction

extends maximum

> life span or life expectancy in lean humans. However, calorie

restriction in adult men

> and women causes many of the same metabolic adaptations that occur

in calorierestricted

> rodents and monkeys, including decreased metabolic, hormonal, and

inflammatory

> risk factors for diabetes, cardiovascular disease, and possibly

cancer. Excessive

> calorie restriction causes malnutrition and has adverse clinical

effects.

>

> Conclusions Calorie restriction in adult men and women causes

beneficial metabolic,

> hormonal, and functional changes, but the precise amount of

calorie intake or

> body fat mass associated with optimal health and maximum longevity

in humans is

> not known. In addition, it is possible that even moderate calorie

restriction may be

> harmful in specific patient populations, such as lean persons who

have minimal amounts

> of body fat.

>

> JAMA. 2007;297:986-994

>

[Guest guest]

>>"In addition, it is possible that even moderate calorie restrictionmay be harmful in specific patient populations, such as lean personswho have minimal amounts of body fat." I thought this statement was kind of ironic. If someone is "lean" and has a "minimal" amount of body fat, they had to accomlish that one of two ways... 1) practice some form of CR 2) enage in excessive amounts of exercise. If it is number 1), then they are already practicing CR and I think the caution is appropriate to not go to far, or to an extreme for them. For them, I also think making sure their intake is not only CR but also ON, while maintaining their weight, would be a more appropriate recommendation. If it is number 2), then that may have its own issues above and beyond

extreme CR. I think the caution to not go below 18.5 is fair. As Rodney mentioned, just getting from a BMI of 22 to 18.5 is not easy. I know for me, I didnt experience the "gray zone" untill my BMI was under 17 and my body fat close to 5-6%. For someone my height, a BMI of 20 equals a weight of ~125. A BMI of 18.5 is equals a weight of ~115 and a BMI of 17 equals a weight of ~105. Going from 115 to 105 would be quite the challange. I try to maintain it between 18.5 and 22.5 with it usualy right between 19.5 -20.5 RegardsJeff

[Guest guest]

Hi Tony:

From time to time here we have discussed how one can judge when one's

caloric restriction has gone far enough. Here is a suggestion to

consider:

Since CRON is associated with some pretty specific, and in some cases

rather large, improvements in certain biomarkers, perhaps a case can

be made that, when implementing CR, body fat may safely be lost until

it reaches EITHER of two levels:

A) Dr. Walford's 'never go below' levels - which differ considerably

by gender, or

When the rate of improvement in health status biomarkers slows

down, or reaches levels similar to the averages seen in the 'WUSTL

study'. The biomarkers I have in mind are things like: blood

pressure; hsCRP; fasting insulin; triglycerides; HDL; WBC; and no

doubt others .........

In other words, when diminishing returns begin to set in you have

gone far enough ............. trying to squeeze a couple more

points out of systolic blood pressure, for example, by dropping a

little more body fat may provide only marginal additional benefit

while possibly creating risks.

I believe it was Warren who posted here a couple of years ago that in

one study of CR mice, all of which were fed an identical number of

calories, the ones that lived the absolute longest tended to be those

that managed to retain the highest body fat. Of course the

implication seems to be that they were burning a smaller number of

calories and storing them instead. (I forget Warren's source for

this information).

Rodney.

>

> We still remember the discussions of the " gray zone " , where CR

proved

> to have some detrimental psychological effects when the percent of

> body fat got too low.

>

> Now, Dr. Luigi Fontana has taken a stand on the side of caution with

> his conclusion regarding CR and low body fat:

>

> " In addition, it is possible that even moderate calorie restriction

> may be harmful in specific patient populations, such as lean persons

> who have minimal amounts of body fat. "

>

> Tony

>

> --- In , Jeff Novick <chefjeff40@>

wrote:

> >

> > Aging, Adiposity, and Calorie Restriction

> > Luigi Fontana, MD, PhD

> > Klein, MD

> >

> > Context Excessive calorie intake and subsequent obesity

increases

> the risk of developing

> > chronic disease and decreases life expectancy. In rodent models,

> calorie restriction

> > with adequate nutrient intake decreases the risk of developing

> chronic disease

> > and extends maximum life span.

> >

> > Objective To evaluate the physiological and clinical

implications

> of calorie restriction

> > with adequate nutrient intake.

> >

> > Evidence Acquisition Search of PubMed (1966-December 2006) using

> terms encompassing

> > various aspects of calorie restriction, dietary restriction,

> aging, longevity,

> > life span, adiposity, and obesity; hand search of journals that

> focus on obesity, geriatrics,

> > or aging; and search of reference lists of pertinent research

and

> review articles

> > and books. Reviewed reports (both basic science and clinical)

> included epidemiologic

> > studies, case-control studies, and randomized controlled trials,

> with quality of data assessed

> > by taking into account publication in a peer-reviewed journal,

> number of animals

> > or individuals studied, objectivity of measurements, and

> techniques used to minimize

> > bias.

> >

> > Evidence Synthesis It is not known whether calorie restriction

> extends maximum

> > life span or life expectancy in lean humans. However, calorie

> restriction in adult men

> > and women causes many of the same metabolic adaptations that

occur

> in calorierestricted

> > rodents and monkeys, including decreased metabolic, hormonal,

and

> inflammatory

> > risk factors for diabetes, cardiovascular disease, and possibly

> cancer. Excessive

> > calorie restriction causes malnutrition and has adverse clinical

> effects.

> >

> > Conclusions Calorie restriction in adult men and women causes

> beneficial metabolic,

> > hormonal, and functional changes, but the precise amount of

> calorie intake or

> > body fat mass associated with optimal health and maximum

longevity

> in humans is

> > not known. In addition, it is possible that even moderate

calorie

> restriction may be

> > harmful in specific patient populations, such as lean persons

who

> have minimal amounts

> > of body fat.

> >

> > JAMA. 2007;297:986-994

> >

>