--- In morelife@yahoogroups.com, "Erich Brueschke"
<erich_brueschke@...> wrote:
>
> Here are 2 studies concerning the relationship between nutrition and
> circadian rhythm that were posted on the yahoo fasting group. I
> checked to see if you all were members before posting this message and
> I didn't see your names, so I assume that you have not seen the
> posting. I feel it might be of interest to you as you have recently
> stated that you have changed to a modified fast for your daily eating.

[snip of Paul's previous meta comment. **Kitty]

I was a member of the yahoo fasting group for a while but found it to
be too concerned with weight loss and chatting and not sufficiently
with science, so I quit.

>
> Erich
>
> The relationship between nutrition and circadian rhythms in mammals.
> http://pmid.us/17451793
>
> The interrelations among feeding, circadian rhythms and ageing.
> http://pmid.us/17482337
>
> Source: http://tech.groups.yahoo.com/group/fasting/message/1257

Olafur had access to the full text of both of the above and kindly
sent them to me.
Reading them (Oren Froy was the major author of both) did not reveal
much that was of practical significance (to me at least) with respect
to how one should schedule one's eating nor with respect to what one
should eat. Here is a general summary of what I got out of them using
the following definitions:
CR = Calorie restriction
IF = Intermittent feeding (a total fast every other circadian cycle)
RF = Restricted feeding (eating is only allowed during a certain
duration of the day) - while the amount of food was not restricted,
there appeared to be no clear definition of either the length of
duration for which this term was used (the authors appears to give
anything from 3 - 12 hours, which is a huge variation), nor was there
any specification of when in the circadian cycle this feeding time
occurred (which I also think would make a huge difference).

1) Strong rhythms of about 24 hours (ie. circadian) for many
physiological parameters are highly important to maintain for health
and longevity.

2) The amplitude (strength or variation in value) of such rhythms
generally decreases as one ages.

3) I say "about 24 hours" because the cycle is not directly regulated
to be 24 hours, but is instead reset or resynchronized every day by
various inputs to the body such as light/dark, eating, activity, etc.
Therefore, in order to maintain a strong circadian rhythm it is highly
important to be as regular as possible in *all* of one's daily
activities.
There appears to be no research about any strongly entrained
(constantly strongly resynchronized) cycle time different than 24
hours (such as I and Kitty were doing when on a 28 hour cycle for over
2 years). The only research has been on free running cycles (not
strongly resynchronized) and severely changed cycles (eg. constantly
changing shift work, constantly changing time zones or swapping night
with day each week). All of these constant or periodic (fairly short
period) changes to the circadian cycle appear to be negative for both
health and longevity.

4) Both CR and IF appear to maintain the circadian amplitude with age
better than for controls. It was not clear to what extent RF helped
the circadian rhythm, but that is likely because of the lack of clear
specification of the different possible types and arrangements of RF,
as pointed out above.

5) It is difficult to completely separate the effects of CR and RF
because CR almost necessarily implies that the feeding time is also
restricted unless only a small amount of food is put out several times
per day (a lot of work with animals), because the animals will eat up
all the reduced amount of calories in a relatively short duration. In
effect, what I and Kitty (and other once a day eaters) do is the type
of feeding which has been done with most CR animals experiments. The
animal is given a reduced amount of food once a day at a certain time
and it eats up that food in a fairly short duration and then has not
food for the remainder of the circadian cycle. We currently eat pretty
much all that we feel able to eat within 3-4 hours and nothing outside
of that time (usually starting about 7 hours after rising and thus
ending about 5-6 hours before sleep). Even though this is all that we
feel able to eat within that time period, it is most certainly is not
an ad lib diet, which is shown by the fact that we have not gained
weight (in fact my weight is more stably at its low point of 137-139
lbs) and we still need to take the special measures that we developed
on CR in order to prevent unacceptable hunger.

6) One concern that I (and some others) have always had about the
applicability of mouse/rat IF experiments to humans is the vast
difference in the metabolic rate. This would mean that metabolically,
every other day feeding for a mouse would be more equivalent to every
other week feeding for a human. Because these papers relate the effect
more to circadian rhythm, although the question is never directly
addressed, it now appears that every other day feeding for a human may
well mimic the effects of that same regimen in a mouse or rat.

7) If one could get used to IF, particularly if one combined it with
CR, that might be best of all with respect to circadian rhythm and
perhaps health and longevity. I plan to try that at some point in
time. My initial thoughts are that it will lead to greatly reduced
productivity for me. I will feel too hungry during the evening of the
fasting day and too over-stuffed during the evening of the feeding
day. But I will approach it with an open mind, since I also did not
think that I would be comfortable and productive on one meal daily
until I tried it and found that it was quite acceptable.

--Paul

[Olafur is reading the full texts of these 2 papers now and will post a separate
message when he's done. **Kitty]