[This message was delayed because I and Kitty were traveling and had no Internet
access for several days. --Paul]

--- In morelife@yahoogroups.com, "Paul Antonik Wakfer" <paul@...> wrote:
>
> --- 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.

Thanks Erich, the papers were very interesting to read. If you or any
other member of the group wants a copy of the full text articles I'd
be glad to send them to you.

> [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.

I bookmarked the Yahoo fasting group a while ago but never joined it.
After reading few of the messages there I decided it wasn't worth my
time to join or follow the posts of the group regularly basically for
the same reasons Paul mentioned.

> > 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.

It did not reveal much of practical significance to me either. However
with respect to maintaining a strong circadian cycle, when one eats
appears to be much more important than what one eats. Keeping one's
meal times regular appears to be beneficial in this respect, although
the exact timing of meals that is of most benefit with respect to
maintaining a strong circadian rhythm is not clear.

> 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.

Disrupting the circadian rhythmicity in hamsters has been shown to
reduce their longevity while increasing the amplitude of the circadian
rhythm in old hamsters by giving them suprachiasmatic implants has
been shown to increase their longevity (PMID: 9783234). If the same
holds true for humans, as evidence suggests it does, maintaining
strong circadian rhythms in humans is very important for health and
longevity.

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

Which means that as one ages it becomes increasingly important to
maintain a regular schedule in all of ones activities in order to keep
the amplitude closer to youthful levels. This is not to imply that it
isn't also important when young, the amplitude of the circadian rhythm
of a young person could easily be reduced to levels similar to that of
an old person by a constantly changing schedule that keeps the various
biological clocks out of sync resulting in reduced amplitude.

> 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 is a master clock located in the suprachiasmatic nuclei (SCN) of
the anterior hypothalamus in the brain which is the main regulator of
circadian rhythm in humans. The main regulator of this clock is light
that enters the retina. There are also other circadian oscillators
located in various parts of the body which receive input from the
master clock and are in large part regulated by it. However these are
not only regulated by the master clock but also by various inputs such
as the timing of food intake and exercise. These so called peripheral
oscillators, while being regulated in large part by the master clock,
can in turn also effect the master clock by sending signals to it.

My interpretation of this research is that while it is important to be
regular in all of one's daily activities, one's sleeping schedule is
probably most important of these since the onset of sleep dictates the
onset of the absence of light exposure to the retina which is the main
regulator of the master clock. After maintaining a regular sleep
schedule maintaining regular meal times and regular exercise times is
probably next in importance with respect to maintaining a strong
circadian rhythm.

One thing that may be helpful for maintaining a strong circadian
rhythm is melatonin supplementation. Light entering the retina is the
main regulator of melatonin production (the absence of it allows
melatonin production to proceed). Melatonin appears to mediate a part
of the effect of light on the master circadian clock in the SCN. This
is suggested by research on blind people in which melatonin
supplementation at 24 hour intervals has been shown to cause
synchronization of their circadian rhythm, which otherwise is free
running because of the lack of signaling of light to the circadian
clock (PMID: 17420154, PMID: 16393710). The best use of melatonin for
this purpose would likely be to combine it with a regular sleeping
schedule and take it just before sleep at the same time every day.

> 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.

RF can uncouple the master clock in the SCN from the peripheral
circadian clocks. Research suggests that many parameters that are
usually regulated by the master clock can be phase-shifted by RF to
the time of food availability (PMID: 11114885). This highlights the
importance of regular meal times for maintaining strong circadian
rhythms. Whether one is practicing CR or not it appears to be very
important to have regular meal times. But I think this is particularly
important for those that eat only once daily like Paul and Kitty are
doing, since because their bodies will have been deprived of food for
almost a day at the time they eat their single meal, the meal will
most certainly send a strong signal to the SCN clock. If the timing of
this meal is regular, combined with a regular sleeping schedule, the
result should be particularly beneficial and will probably contribute
to a strong circadian amplitude. If on the other hand the timing of
this meal is irregular the effect on the circadian rhythm may be
particularly harmful since being the only meal consumed during the day
the timing of it will be that more important with respect to the
circadian rhythm.
.
> 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).

As one of the papers explained there exists a transgenic mouse model
called alphaMUPA. AlphaMUPA mice do not need to be fed for only a
restricted period to serve as a model for CR mice since they
spontaneously eat less than wild type mice when fed ad libitum. Yet
these mice have been shown to have higher circadian amplitude than
wild type mice suggesting that at least some of the beneficial effects
of CR on circadian rhythm are caused by the reduction in calories per
se. This is one of the reasons I think CR combined with IF is the best
method for health and longevity, just like Paul suggested below.

> 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 agree that IF combined with CR is probably the best method. I'd
highly recommend combining IF with CR for anyone that can reasonably
maintain such a regimen without too many negative effects.

> 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]

Reading the papers as well as doing research around them and trying to
add something to Paul's informative post proved to be a little more
time consuming than I initially thought it would be. But I promised a
reply so there you have it:-)