Did the quotes stir your interest?  Good, they were meant to do so.  Here
is one more:
 
"Lifelong dietary restriction (DR) or calorie restriction is a well
established and perhaps the only reliable means to delay the functional
decline of cells and tissues with age and the onset of age-associated
diseases, and to extend the life span of a variety of animals."
"...DR initiated much later in life was also demonstrated to have a
beneficial effect: reduction of tumor incidence, resulting in extension
of life, albeit less remarkable compared with earlier onset."
Goto, S., et al.  2002 Dietary Restriction Initiated in Late Adulthood
Can Reverse Age-Related Alterations of Protein and Protein Metabolism.
Annals of the New York Academy of Science 959:50-56.
 
A short discussion of the concept of CR/DR is in order.  Calorie
restriction (CR) and dietary restriction (DR) are essentially synonymous
terms, so from this point I will just refer to it as DR.  The idea that
restricting a ferret's caloric intake can result in profound health
benefits seems to fly in the face of common sense.  After all, it is
basically saying, "Your ferret is ill, so let's cut back on the amount
of nutrients we are going to feed it...that should do the trick!"
Intuitively, such a suggestion HAS to be crazy!  Sick ferrets NEED as
many nutrients as they can get just to get better, especially caloric
energy, right?  And yet, there are all those repeatable, exhaustive data
that say the exact opposite.  It is no wonder scientists have been slow
to publicize their findings.  This dietary concept is so
counter-intuitive that scientists themselves have a hard time accepting
the implications.  The greatest problem is that while the phenomenon is
measurable, the exact mechanism WHY it works is not clearly understood;
a scientific black box.  The reluctance of scientists to stress the
importance of DR is probably related to a lack of understanding of the
working mechanism, NOT the observation that it prolongs life and improves
health.
 
One thing DR is NOT and that is malnutrition.  That has to be perfectly
clear from the beginning.  DR is a restriction of nutrients, but NOT one
that causes a depletion of body stores for ANY nutrient.  Put in other
words, it is the practice of feeding a ferret the MINIMUM nutrient
requirements, rather than allowing them to eat in excess on needs, as is
done on an ad libitum diet.  The exact safe level of DR is still under
investigation, ranging from a 20% to 40% reduction.  At 40%, the ferret
experiencing DR is on the verge of some type of malnutrition, and the
benefits of the dietary practice seem to be maximized.  20% DR, while the
benefits are obvious, they are not maximized.  A 30% DR seems to maximize
health benefits while maintaining a reasonable store of nutrients--a
sort of dietary safety net.  What this means is, a ferret that would
normally consume 100 units of feed, would be restricted to only 70 units.
The practical result would be a ferret would be hungry ALL the time (not
painfully, but that restless feeling you have when prowling for a snack).
This finding has been reported by humans who have voluntarily placed
themselves on a similar diet.
 
In a practical sense, what does it mean to be slightly hungry all the
time?  Is it unhealthy?  Obviously not, or the extended data reliably
linking DR to longevity, reduced cancers, and increased health would be
wrong.  DR animals are generally described as lean and muscular.  Is it
unnatural?  Again, not likely.  Ferrets are domesticated polecats that
have evolved as primary carnivores.  Starvation is the ultimate leading
cause of death in wild carnivores, so it is likely MOST live in a natural
state of DR most of their lives.  Considering the ferret trait to hide
food for later, it is likely the polecat evolved in a constant state of
DR.  Does it cause stress?  Probably, but not all stress is unhealthy.
In this case, the stress would probably cause a ferret to show more
interest in their surroundings, much more interest in food (training
implications are profound), and much less wasteful at the food dish, and
far less 'forgotten' tidbits of food hidden away 'for later.'  Can it
work with ferrets that are already ill?  Some do it themselves; it mimics
an evolutionary adaptation to illness in mammals.  Most mammals, when
ill, go 'off their feed.'  Not only does this change the microecology
within the body, but it reduces essential nutrients available for the
invading pathogens.  Some nutrients are actually taken out of the blood
stream, sequestered in other areas of the body during the illness.  The
more you look at DR, the more you realize it is a natural phenomenon.
Rather than causing serious problems, DR seems to tap into the ferret's
built-in mechanisms to fight disease, as well as limiting exposure to a
variety of environmental toxins, including natural oxidants and human
pesticides.
 
Bob C
[Posted in FML issue 3951]