Subject: Sci.life-extension FAQ #4: Calorie Restriction

From: [email-masked] (Brian Manning Delaney)
Date: Wed, 9 Mar 1994 14:52:35 GMT

(Sci.life-extension FAQ #4.)            January 27, 1994 Edition.

                         Calorie Restriction

The following FAQ was written by Julius Pierce ([email-masked]),
a knowledgeable, experienced Calorie-restricting longevist. I made a
few minor suggestions and alterations.

-Brian <[email-masked]>.

[ ] Calorie Restriction FAQ.

    This FAQ will only "scrape the surface" of what is
    known about calorie restriction (CR).

Q0. Where can I find out more about calorie restriction?

 -> The 120-year diet
    Roy L. Walford (1986)
    ISBN: 0-671-46677-1
    [cheap paperback: 0-671-74474-7, 1988]

    _The_ pragmatic introduction for anyone who wishes to undertake
    CR personally.  A description of "how to" for human CR separates
    this book from research or more technical descriptions of CR.

 -> The retardation of aging and disease by dietary restriction
    Richard Weindruch and Roy Walford (1988)
    ISBN: 0-398-05496-7

    A more technical description of physiological effects of CR.
    Contains details of research on animals,  and some reasoning
    about the underlying mechanism and how the research might be
    extrapolated to humans.

 -> Biological effects of dietary restriction
    edited by Lawrence Fishbein (1991)
    ISBN: 0-387-52294-8

    An anthology (27 different papers) of research in dietary restriction
    from a conference in 1990.

    I will quote frequently and remorselessly from the above books in
    what follows.  (I also recommend reading pp 24-37 in "the 120-year
    diet"  for more "FAQs".)

Q1. What is calorie restriction (CR)?

    This is a question which,  unfortunately,  is not asked frequently
    enough.  Many who have used the term in this newsgroup blithely
    assumed that CR means _only_ "a reduced-calorie diet".  In the
    context of technical discussions on aging,  they are incorrect.

    "Calorie restriction" is a dietary change from a normal nutritional
    diet to a diet which has the same levels of nutrients,  with _only_
    caloric content reduced.  This distinguishes CR from malnutrition,
    starvation,  and "eating less".

    The term, CR, is sufficiently misdirecting that many other terms
    have been used,  such as:  "undernutrition without malnutrition",
    "caloric optimization",  and "iso-nutrient diets" (in comparison
    or control studies.)

    There are yet other terms with possibly different technical connotations
    (than CR) which one may encounter in the technical literature,
    such as:  "dietary restriction" (DR),  "every other day" feeding
    (EOD),  and "chronic energy intake restriction (CEIR).

Q2. What are the biological effects of CR?

     In the overwhelming majority of animals studied,  CR
    "slows biological aging" or extends maximum life-span.

    CR animals are thinner,  live longer,  and have lower disease
    incidence than ad-libito fed controls.  In general,  practically
    all the biomarkers of aging suggest that CR animals are younger than
    there control "peers" of the same biological age.

    In some sense,  it appears that there is a "biological clock" which
    can be controlled to a degree by caloric intake.

    The degree to which CR may change biological aging rate in experimental
    animals is so great that longevity or senescence studies which do
    not include CR control animals are "difficult" to interpret.  For
    instance,  there is epidemiological evidence that a high-fat intake
    is positively correlated with a higher cancer incidence.  A high fat
    intake is also likely to positively correlate with an increased caloric
    intake,  increased biological aging rate,  and therefore an earlier
    chronological age of cancer onset.  So,  was it the high-fat fraction
    in the diet that caused the cancer or the high calorie consumption?
    CR studies indicate that the nutrient source of the calories is not
    the most important factor,  but it is the total caloric intake,  instead.

    The above example is just an illustration of the difficulty of
    interpreting studies which don't control for CR,  and not as a
    "Good Idea" for extrapolation into human diet.  Low fat diets,
    being less calorie-dense,  may provide a greater feeling of satiety,
    among a bazillion or three possible other objections.  The point is
    that CR has a sufficiently powerful effect on the biomarkers of aging,
    and longevity,  that it must be considered in any experiment on
    senescence.  It is this very life-extending effect of CR which
    interests some humans in the possibility of personal application.

    The known species which are exceptions are very genetically distant
    from humans,  so these exceptions don't really represent counterexamples
    against the hypothesis that CR will work in humans.  For example,
    amoebas may become immortal when "over-fed",  or honey bees
    may turn into a longer-lived variety.

    Most of the answer to this is beyond the scope,  here.  The answer
    to this question occupies entire books :).

Q3. How does CR extend the life span of animals?

    Rather effectively,  I think :).

    There is no one-liner consensus from researchers
    about "the" mechanism underlying CR.  If you happen to find out,
    Ponce de Leon and I want to hear about it.

    A common conjecture is that it "makes sense" (pardon me as I
    wax teleological) from an evolutionary perspective that an
    organism experiencing scarcity of food "should not" reproduce,
    but instead "should attempt" to outlive the scarcity.

    Weindruch & Walford claim that the evolutionarily selected adaptive
    response involves a selective upregulation in repair and protective
    processes,  an increased metabolic efficiency,  a decreased production
    of damaging agents,  and signals to the neuroendocrine network
    (particularly the hypothalamus.)

Q4. What's the evidence, pro and con, that CR will work for humans?

    /* meta on */

    You may arguably expect bias here,  as I have already decided the
    evidence is sufficient to implement CR personally.  On the other
    hand,  I will trade it in for superior methods,  if or when they
    arrive.

    I don't believe that compelling evidence exists against the proposition
    that CR will extend life span for humans.  I also recognize that
    those who claim CR works in humans have the burden of proof.

    When one brings up the idea of "proof",  one should kindly outline
    one's criteria for proof,  or the nature of evidence one will accept.

    Some kinds of proof are not practical,  even if possible,  in the
    question,  here.  We would not live to see the results of a double-
    blind study of CR on human longevity.  Many such experimental
    arrangements would be illegal or considered unethical.  It doesn't
    seem likely that the CR humans and the ad libitum humans wouldn't
    be able to figure out which group they were in.

    If one expects such stringent standards of proof,  then one is also
    likely to be skeptical of claims that cigarette smoking shortens
    life span,  or that pushing people in front of fast-moving trains
    shortens their life span (where _are_ the published studies :).

    The time constraint has interested many researchers in "biomarkers
    of aging",  measuring biological changes with aging in order to
    compare those measurements in CR and ad libitum groups.

    The subject here is the subject of other entire volumes,  so I will
    attempt to present an absurdly compressed synopsis of evidence that
    I think is relevant,  attempting as great an injustice as possible
    to the crucial details that each researcher so carefully elucidated,
    as well as omitting 99% of the relevant studies. :) :) :)

    /* meta off */

    Some research:

    1978 Kagawa:  The Okinawan population more closely approximates
    a CR group than their neighbor-island "controls",  and the Okinawans
    live longer.

    1957 Vallejo, cited by 1976 Stunkard:  Controlled EOD study in elderly
    demonstrates EOD group spent fewer days in the infirmiary (123 days
    average) than the higher calorie-intake controls (219 days average)
    (p < 0.001).

    1978 Bowers & Eckert:  Anorexics, in the early stages, show normal
    or increased resistance to infection.

    1979 Skoldstam & Lindstrom:  Fasting shows favorable effect on
    an autoimmune disease.

    1984 Hughes et al.:  Insulin resistance is decreased by DR in humans.

    1980 Andres & 1980 Keys:  Heaviest and thinnest individuals in human
    population have shortest survival.

    There are also many arguments about whether, or how, the extensive
    data collected on animals extrapolates to humans.

Q5. How does a human do CR?

    Slowly.  CR requires a gradual descent in caloric intake over
    at least four to six years.  Abrupt change to a CR diet in adulthood
     _shortens_ the life span of animals.  Non-adult humans need not apply.

    ... and quantitatively.  I have designed quite a few diets for CR,
    and I believe computer techniques are required for any such design.
    Some different menus appear in Walford's "120-year diet" which were
    also designed by computer.  I suspect that anyone who believes they
    can design diets which are high in nutrition and low in calories,
    appropriate for CR,  without computer assistance hasn't tried it.
    A diet that is inadequate in essential nutrients also shortens life
    span ... it's called malnourishment.

Q6. Why not do CR?

    /* speculation on */

    You may not believe the evidence that CR extends human life span.

    You may wish to "optimize" yourself for something other than a lower
    incidence of disease and longer life span.  You will not likely
    become an olympic gold medalist in most events while doing CR.
    (You will not likely become an olympic gold medalist,  period :).
    Females should (or "must") cease CR to reproduce.

    On the relatively rare occasions when I go cross-country skiing,
    I find it convenient to eat a relative excess of carbohydrates.  I
    do this because hypothermia is a greater possibility for one who
    does CR,  and because I'll need the calorie reserves.  But,  if
    the tiniest diminishing returns in aerobic performance were
    all-important to me,  then I wouldn't do CR "globally".

    You may not think that the dietary change is worth the cost.  I've
    heard,  "most people would rather change their religion than their
    diet."  My own opinion is that most people are not cut out for CR while
    the current environment in which we live does not socialize them into it.
    Such social forces,  the gigabucks spent by advertisers and food
    "industries" in bending our preferences,  and our "internal demons"
    which encourage us to live fast and die young,  all of these are
    important forces which are frequently underestimated.  Most people
    I have known who started CR have already quit.  'Tis best they never
    wasted their time with it in the first place.  I've heard (pan knows
    where) that the vast majority of people in weight-loss programs
    regain their weight within a year.  I would think that CR would be
    even less motivating,  as the gratification is even less immediate.
    That is,  the weight losers got rapid confirmation that their program
    worked.  To do CR successfully,  even weight change must be very
    gradual,  and the real goal,  reduced biological aging rate,  is
    more difficult to observe in the short run (compared to weight-loss.)

    Many of us don't really have the inclination or "tools" to quantitatively
    assess evidence,  nor to actualize the conclusions we might reach from
    it.  Many of us aren't inclined to quantitatively analyze our dietary
    intake.  Someone asked me,  "Do you count your pulse-rate while
    making love?"

    Some of us would prefer to attend fewer than 50% of our peer-group's
    funerals.

    Some believe that humans were not "intended" to live a longer life,
    while others are just convinced that us CR folks are possessed by the
    devil.

    /* speculation off */

Q7. Why do CR?

    /* speculation on */

    Practitioners believe they will live longer,  or be "biologically
    younger" than their chronological age.

    There is no technique which produces comparable gains in life span
    (or reduction in "biological aging" rate.)

    Some of us perceive the added "CPU cycles" to be a purchased at a
    very modest price.

    Walford says,  about those for whom angel-food cake is more
    important than sight,  sense,  and sexuality,  "let them eat cake."

    There's no accounting for taste :).

    Doubling our remaining life expectancy is attractive for some of us
    with long-term goals.

    How many 40-year-olds wouldn't trade for the body they had at 30?

    How many 80-year-olds wouldn't trade for the body they had at 50?

    It is difficult even to speculate on what a gain of 30 years in
    life expectancy might mean,  these days.  I personally am rather
    curious to see the spinoffs from the human genome project.  A gain
    of 30 years now may mean a "lifetime" of enormous length.

    Who will care about that tiny little slice of time they did CR,
    when they consider the richness of alternatives available in 3793?

    /* speculation off */

[ ] Addendum.

-Is CR really PR?

A few people (including Julius, who wrote the first part of this FAQ)
have pointed out to me that the effect of food restriction may
actually result from protein restriction, not calorie restriction. It
was thought by most researchers that this possibility had been ruled
out, but a careful look at the literature shows that this may not be
so.  An interesting twist: a couple of studies have been done
restricting _just one_ amino acid, with a resulting extension of life
comparable to that of CR.

There are theoretical reasons to suppose that both PR and CR
contribute to the effect of food restriction. More work needs to be
done.

(I'm going to continue to use "CR" when talking about food
restriction, even though "PR" may be important, too. "CR" has become
convention.)

-Loss of Lean Body Mass.

A few people in Sci.life-extension expressed concern that they would
lose lean body mass (muscle) on CR. There's little evidence that this
occurs when CR is instituted in adulthood. It may occur to a slight
degree, but this can probably be offset with resistance training
(weight-lifting).

A recent study on primates doing CR showed that lean body-mass
remained unchanged in the experimental animals [1]. (But this was just
in the early part of the study).

-CR by the Fasting Method.

Instead of eating less on daily basis, studies have shown that rodents
fed all they can eat most days, but fasted every two, three or four
days, have an increase in longevity comparable to that of rodents on
the standard kind of CR. For people, this might be an easier way of
doing CR: 1) you could limit your hunger to two or three days a week,
2) and you wouldn't have to lose as much weight (the extreme
restriction of the fasts seems to have a longevity-enhancing effect
w/o an extreme avg. reduction in caloric-intake).

This would need to be instituted slowly, like standard CR.

-Nutrient Data in Electronic Form.

The USDA's nutrient database is publicly available at info.umd.edu.
Look in the directory info/Government/US/NutrientData. A few people on
the Net have written software to read the data. Ask in
Sci.med.nutrition (or in Sci.life-extension). Recently, flaws in the
data have come to light, but the data set is probably fairly reliable,
on the whole.  There are a few commercial nutrition analysis programs
available that have far more complete, reliable data. They are quite
expensive, though. Many of these programs were evaluated in the
January, 1992 issue of the Journal of the American Dietetic
Association. This journal runs ads monthly on new programs.  Some of
the companies will send demo disks.

-"But I Thought Fat People Live Longer!?!"

Some data made the rounds ten or fifteen years ago that showed that
thinner people died earlier than avg. or slightly overweight people.
This has nothing to do with CR. First, there are several problems
w/the data.  Two (of many) examples: 1) the compilers of the data
didn't control for smoking (people usually gain weight when they quit
smoking, but they live longer since they aren't as much at risk for
lung cancer); 2) they didn't control for inflammatory bowel disease
(IBD makes people thin, but people w/IBD have a higher rate of
intestinal/colon cancer, and are often malnourished).

Secondly, the point of CR isn't to be thin, it's to eat less.
Overweight people are under social pressure to be thin, so they may be
more likely to eat less than skinny people, who often can eat as much
as they want w/o gaining weight. So even if heavier people DID live
longer than thin, healthy non-smokers, it wouldn't constitute evidence
against CR's applicability to humans.

-Skepticism about CR.

At the moment I'm slightly less optimistic about CR than I was a year
ago (but only slightly). There's virtually no doubt that CR will
prolong the life of humans, but I'm not sure the percentage gain will
be the same as it is in rodents. The reasons for my skepticism are
complicated and probably not worth going into at the moment (it's not
just the human:rodent life span ratio applicability problem). I think
we need to wait to see the results of the two primate CR studies that
are currently underway. This should go a long way towards resolving
the issue.

Even with my skepticism, I still think CR is the best bet for a
longevity-enhancing regimen, and I have no plans to stop doing it.
Even if the gain turned out to be fifteen years and not twenty to
thirty, I'd still say it's worth it.

-Scales 'n Things.

A mail-order company from which very cheap scales and other
health-related equipment can be purchased is:

   Creative health Products
   5148 Saddle Ridge Road
   Plymouth, MI 48170

   800-742-4478
   313-453-5309

Pardon the rough editing,
Brian Delaney <[email-masked]>

[ ] Notes.

[1] Kemnitz JW; Weindruch R; Roecker EB; Crawford K; Kaufman PL;
Ershler WB. Dietary restriction of adult male rhesus monkeys: design,
methodology, and preliminary findings from the first year of study.
   Journal of Gerontology, 1993 Jan, 48(1):B17-26.
-- 
Brian M. Delaney <[email-masked]>
              or <[email-masked]>