FW: BMI (How tall is M.C. Colella?) -

[Guest guest]

=========

I started a knee-jerk response last night along the lines of " it's the

calories not the BMI " but deleted it since it wasn't very informative

(that's why there's a " Jerk " in knee-jerk).

While I'm not sure I have a much better answer today, lets begin with a

little Sherlock Holmes style eliminating what isn't useful or accurate.

There is no doubt that body weight is intimately related to energy intake.

Pretty much universally increasing energy intake will always increase body

weight, and reducing energy will reduce weight. While the arrows pretty much

always agree the relationship is far from precise or specific. While there

are numerous equations purporting to define a relationship, there are

numerous anecdotal exceptions either due to flawed assessment of energy

intake, activity level, etc etc.... bottom line not very reliable.

BMI, IMO is a metric which has gained popularity far beyond it's utility due

to simplicity to calculate. Notable confounders to BMI measurement are frame

size (yup I got dem heavy bones), musculature and/or %BF, not-yet and

never-to-be-digested foods in our alimentary canal, and lastly hydration

level. In other words BMI may be reasonably useful for homogeneous

populations of caged animals on similar diets, activity levels, etc. For a

diverse population of humans it's not very precise.

% Caloric Restriction. All of the evidence suggests that %CR is a useful

metric but once again this is far easier to calculate as a relative metric

between homogeneous populations of lab animals. Trying to determine a set

point weight or set point caloric intake for human individuals is beyond my

comprehension (despite numerous rules-of-thumb).

Just like energy restriction is intimately related with weight loss it is

also intimately related to increasing success in the measured benefits of

CR. So despite not being able to predict where we are on the curve, less

energy intake will pretty much always be better, until a point.

Just like the difficulty in determining where we fall on the CR continuum

how do we know when we've gone too far. The popular suggestion is monitoring

% BF and keeping above some minimal amount (%5 male/10% female). Many active

CRONies report impossible negative BF readings. A testament to the

inaccuracy of popular bioimpedance measurements. I also suspect percentage

BF may have been used for convenience and a real safety reservoir of energy

might more appropriately be X lbs of fat. This is somewhat baked into

current guidelines as women are typically smaller than men and often carry

less muscle mass which could also be burned in emergency.

It might be of value to hear from one of our regular posters, Al Pater who

is AFAIK our only openly anorexic, or was anorexic, or something like that.

While I don't wish to scare new comers from this grand experiment, maybe a

little caution about extreme restriction is useful.

Al, what would you add about safe lower limits to energy intake, or BMI, or

weight, or whatever?

Sorry, If I haven't provided an absolute answer but I hope I've eliminated

some of what isn't. Not so elementary my dear ....

JR

-----Original Message-----

From: citpeks [mailto:citpeks@...]

Sent: Thursday, May 06, 2004 10:49 PM

Subject: [ ] BMI (How tall is M.C. Colella?) - Thanks

Thank you to all the persons who provided the height information for

(6'3 " , 165 lb).

>From the height/weight data I calculated that 's current BMI

is 20.7 which is just below the middle of the " normal " BMI range

(18.5 - 24.9).

It is interesting to note that at a weight of 195 which corresponds

to a BMI of 24.4, the high end of the normal range, had " a

stubborn blood lipid profile and dependence on high dose zocor " which

normalized when he achieved his current weight of 165 lb.

The lesson here seems to be that it is better to have a BMI in the

middle of the " normal " range than in the upper part of the range.

A. Zamora

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[Guest guest]

--- In , " john roberts " <johnhrob@n...>

wrote:

> =========

> I started a knee-jerk response last night along the lines of " it's

the

> calories not the BMI " but deleted it since it wasn't very

informative

> (that's why there's a " Jerk " in knee-jerk).

>

> While I'm not sure I have a much better answer today, lets begin

with a

> little Sherlock Holmes style eliminating what isn't useful or

accurate.

>

> There is no doubt that body weight is intimately related to energy

intake.

> Pretty much universally increasing energy intake will always

increase body

> weight, and reducing energy will reduce weight. While the arrows

pretty much

> always agree the relationship is far from precise or specific.

While there

> are numerous equations purporting to define a relationship, there

are

> numerous anecdotal exceptions either due to flawed assessment of

energy

> intake, activity level, etc etc.... bottom line not very reliable.

>

> BMI, IMO is a metric which has gained popularity far beyond it's

utility due

> to simplicity to calculate. Notable confounders to BMI measurement

are frame

> size (yup I got dem heavy bones), musculature and/or %BF, not-yet

and

> never-to-be-digested foods in our alimentary canal, and lastly

hydration

> level. In other words BMI may be reasonably useful for homogeneous

> populations of caged animals on similar diets, activity levels,

etc. For a

> diverse population of humans it's not very precise.

>

> % Caloric Restriction. All of the evidence suggests that %CR is a

useful

> metric but once again this is far easier to calculate as a relative

metric

> between homogeneous populations of lab animals. Trying to determine

a set

> point weight or set point caloric intake for human individuals is

beyond my

> comprehension (despite numerous rules-of-thumb).

>

> Just like energy restriction is intimately related with weight loss

it is

> also intimately related to increasing success in the measured

benefits of

> CR. So despite not being able to predict where we are on the curve,

less

> energy intake will pretty much always be better, until a point.

>

> Just like the difficulty in determining where we fall on the CR

continuum

> how do we know when we've gone too far. The popular suggestion is

monitoring

> % BF and keeping above some minimal amount (%5 male/10% female).

Many active

> CRONies report impossible negative BF readings. A testament to the

> inaccuracy of popular bioimpedance measurements. I also suspect

percentage

> BF may have been used for convenience and a real safety reservoir

of energy

> might more appropriately be X lbs of fat. This is somewhat baked

into

> current guidelines as women are typically smaller than men and

often carry

> less muscle mass which could also be burned in emergency.

>

> It might be of value to hear from one of our regular posters, Al

Pater who

> is AFAIK our only openly anorexic, or was anorexic, or something

like that.

> While I don't wish to scare new comers from this grand experiment,

maybe a

> little caution about extreme restriction is useful.

>

> Al, what would you add about safe lower limits to energy intake, or

BMI, or

> weight, or whatever?....

>

> JR

Hi All,

Thanks for the introduction, .

I believe that you in the above have described as many or more of the

benefits of BMI measurement as those for measuring CR.

The point regarding bone size is well warranted, I believe.

My body fat was measured and could be compared with others in the CR

Society group in the WUSTL studies. DEXA was used, a very reliable

metric.

My body fat % was greater that those of many having greater BMI, but

they had greater muscle mass. Therefore, I believe that our level of

isometric exercise is important.

For me, my ad lib weight/BMI was healthy according to life insurance

tables. My genetically disposed high blood lipids levels were a

concern. My immune system cells were in the low end of the reference

range. My CR history has been at dangerously low levels for me, it

appears. Bone fractures, pneumonia episodes and bronchitis with

continued low-levels of minor respiratory infections have resulted.

My summary is that, while I may be exceptionally sensitive to CR side

effects, greater than approximately 30% loss of our weight at 20

years old is an elevated health risk.

Cheers, Al.