X-Message-Number: 10439
Date: Sat, 19 Sep 1998 17:19:33 -0700
From: Brian Manning Delaney <>
Subject: Calorie Restriction and Epidem. Data


Sorry if this is too off-topic, but I think it's important,
and is a needed corrective to an old message sent to this
list that was also off-topic, but contained a lot of bogus
info. John de Rivaz's pointer to Ben Best's recent article
in his on-line magazine made me realize that Cryonet was one
of the many places to which Doug Skrecky sent one of his
anti-Calorie restriction posts. I responded to the many
other fora to which he sent his message, but missed this
one. I'd hate to see people not try CR for the wrong
reasons. (After all, there are enough GOOD reasons not to do
CR -- above all, pound bags of almond M&Ms.)

This is my original response to his post (I edited it

Date: Wed, 15 Oct 1997

Doug Skrecky wrote:

> In humans it has been found that after physical
> fitness is controlled for, that body weight has
> no effect on mortality, thus strongly suggesting
> that caloric intake is NOT a significant
> modulator of human aging. (19)

Doug, try to think a bit more carefully about possibly
confounding variables before you make claims like the above.

A bit of logic may be useful. You're saying:
1) If A then B;
2) B; ==>
3) Conclude (via a "strong suggestion"): A.

This is fallacious. If (2) is A, then you can (3) conclude
B, yes, but not the other way around. Think of some simple
examples if you don't understand; it's pretty obvious once
you think about it.

Filling in the variables for the case at hand: 1) If someone
is doing Calorie Restriction, s/he is thin (it is strongly
suggested -- I think this is where you intend your
qualification to go); 2) We have a group of people who are
thin; 3) Therefore they are doing CR. (And, therefore, since
these thin people aren't living longer than anyone else --
this, by the way, is wrong -- CR doesn't retard aging in

This is not valid. (Also, as to soundness, someone with a
very high set-point could do CR and not be thin at all.)

Perhaps your thinking is rather this: 1) if someone is thin,
they're doing CR; 2) We have a group ....

Here the problem wouldn't be one of logic, but rather of a
fatal lack of facts. It's hard to imagine that this is your
problem here, but in case it is, a few relevant points

Thinness can be caused by FR (mere food restriction), not
CR. Very poor people, for example, are thin because they
aren't eating enough food. Malnutrition decreases longevity.
You wouldn't contest this, right?

A far more important category of people who are thin for
reasons other than the practicing of CR is people who have
sub-clinical illness. There are _millions_ of them,
according to most epidemiologists. To consider just one of
the many types of disease that can go undiagnosed, consider
celiac sprue. This is a disease of the small intestine (the
jejunum) the effects of which are triggered by a protein in
wheat (and possibly in other grains). The disease results in
weight loss. It is often not diagnosed (_far_ more often
than not, in many countries) until years after the disease
process itself begins. Then there's Crohn's disease,
colitis, etc. (See Acta Paediatr 1995 Jun;84(6):672-676, for
one of many studies dealing with undiagnosed celiac sprue.)

And here's yet another serious problem. First, to recap: we
so far have two groups of thin people who aren't doing CR:
1) those with undiagnosed illness, and 2) those who are
malnourished (people doing FR). But there's a third, very,
very big group: people who are naturally thin.

Doug, are you aware that people vary greatly in "set-point"?
"Naturally" thin people in most cases (close to all cases,
I'd guess) aren't doing CR, they're just disposing of
Calories differently from "naturally" fat people. I'm using
scare-quotes because some of this is nurture, not nature.

Let's, then, consider one aspect of nurture in body weight.
There is a huge social force that compels people to eat
less: the notion that being fat is ugly (or uncool, or bad
in some other way). So who are the people who are going to
feel compelled to change their diet because of this social
pressure? The naturally overweight. The naturally thin will
just keep stuffing themselves (and will remain thin).
Stuffing oneself is not CR. Clear, yes?

And if the naturally thin are naturally thin because they
have a higher metabolism (a notion for which there is some
evidence), then maybe they're aging faster then the
naturally fat would be if the naturally fat controlled their
diets somewhat as a result of social pressure. (This assumes
that a high metabolism generates more free radicals, etc.,
etc. Quite plausible, it seems to me.)

So, in point of fact, the epidemiological issues here are
far too complicated even to begin to try to make suggestions
about a CR effect in humans based on data like that you
cite, let alone "strong" suggestions. (And the logical
connections among the variables are complicated, too --
well, actually, they're not complicated, but, depending on
your interpretation of the facts, you appear to have gotten
them entirely wrong.)


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