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Cold Exposure & Other Mild Stressors for Increased Health & Longevity

Cold Exposure Exercise Fasting UCPs UCP1 UCP3 FGF21

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#141 Saul

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Posted 26 March 2016 - 06:30 PM

Let me also join in by thanking Dean for his prolific, and often very interesting, posting.


-- Saul

#142 Gordo

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Posted 26 March 2016 - 11:36 PM

Dean, thanks for the additional info about skeletal muscle non-shivering thermogenesis (smNST), very interesting.  There still may be an important link between BAT and smNST, I alluded to this earlier, but the quotes from the study (PMID 26993316):

Change (Δ) in BAT DEE as a result of cold stress was estimated to be 4 ± 3 kcal/day; this accounted for merely 1 % of the total change (Δ) in whole-body EE (352 ± 372 kcal/day,


In other words, when it comes to direct thermogenesis, BAT is practically doing NOTHING AT ALL (which still seems a little hard to believe in light of all the prior research and PET scans we've seen).


...we observed significant association between the change (Δ) in whole-body EE (cold induced thermogenesis) and the BAT mass (r = 0.78; p = 0.037, Fig. 5a). 

The more BAT you have, the more smNST you get as well.  It would be nice to know why that is, especially in light of the research you presented showing smNST can happen in the absence of BAT.


Its also worth noting that this study had only seven participants, not a great sample size...

Edited by Gordo, 27 March 2016 - 01:50 PM.

#143 Gordo

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Posted 27 March 2016 - 01:04 AM

Michael, that study (PMID: 16424282) IS indeed a good read.  I'm sure Dean will dig in and do a much better job of commenting on it than I could.  But just at a glance, a few thoughts popped into my head.  For one thing, it seems like a glaring omission that they did not report the housing temps for this study when that was of critical importance.  Both CR groups were 40% CRed, but the singly housed mice weighed 20% less because they were burning up extra calories to stay warm, which in one sense could mean they were the equivalent of "60% CRed" or maybe the multiply housed mice were also cold exposed (we don't know) making them the equivalent of 60% CRed and the singly housed mice %80 CRed.  This study is further evidence that many if not most CR rodent studies have been poorly controlled (i.e. did not properly consider thermo-neutrality).


Next they found that CR w/CE resulted in substantially lower cancer incidence -- that sounds pretty good for CE, however the cold mice died more frequently of "mouse pneumonia". If translated to humans, this might actually be a pretty good trade off.  That said, I think it's fair to say that no human (other than possibly Dean) is going to do CE 24/7 like these mice, so I'm really not sure how relevant these observations are (I doubt anyone has done "intermittent CE" studies on mice, but that would certainly be interesting).  I would also love to see how the CRS vs. CRM comparison would go if the CRS mice were given just enough extra food so that their body weights matched the CRM cohort (effectively keeping calorie balance constant and only having one variable, temperature, changing).


Additionally, Dean previously referenced other studies showing CR w/CE in certain mouse genotypes had substantial life extending benefits beyond CR alone, taking that into consideration, and the fact that in this study lifespans were about the same with or without CE, its still looking pretty good for CE from my perspective. Furthermore, from A. Richardson's ongoing study description "two-thirds of the 41 recombinant inbred (RI) lines of mice studied either did not respond or showed reduced lifespan when fed 40% DR", then you have the primate CR studies showing little or no life extension beyond that of obesity avoidance... makes me want to look at going beyond CR alone.  


But at the end of the day, I think CR/CE/special diets/Exercise are all only capable of fairly limited life extension. We need much bigger technological advances than anything discussed here if we are ever going to cheat death.  Speaking of which, happy Easter everyone!  ;)

Edited by Gordo, 28 March 2016 - 08:47 PM.

#144 Dean Pomerleau

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Posted 27 March 2016 - 10:48 AM



Before getting to this latest study, I made a modest but I think interesting update to my recent big post on sarcolipin, and in particular the section on mitochondrial uncoupling. I added discussion of this study [26]. Below is the updated section. The underlined part is the new stuff, and the rest is mostly rewording:


Tantalizingly, quite a number of studies suggest mitochondrial uncoupling might be associated with increased longevity. Studies [22][23] found that increased UCP-2 expression results in increased longevity in rodents, and this may be associated with body temperature regulation [25], although this result is controversial [24]. Similarly suggestive, [26] found that mice chronically treated with a mild mitochondrial uncoupling agent that works independently of the UCPs (a chemical called 2,4-dinitrophenol or DPN) resulted in mice who ate more, weighed less, had lower measures of fasting glucose, triglycerides, insulin and oxidative damage to DNA, and most importantly, lived longer than controls - mean and maximum (oldest 10%) lifespan were extended by 7% and ~11%, respectively.  And in this post, I talk about the evidence that increased expression of UCP proteins is associated with greater human longevity.


Regardless of the mechanism of mitochondrial uncoupling, and regardless of whether uncoupling is occurring in BAT, skeletal muscle, other organs, or some combination, it appears to be happening as a result of cold exposure, and have the potential to be health and lifespan promoting. The importance of mitochondrial uncoupling for thermogenesis in humans in response to cold exposure is demonstrated by [19], in which resting metabolic rate was increased by 76kcal/day as a result of mild cold exposure (80 hours @ 16 °F), and about half of that increase appeared to result from mitochondrial uncoupling.


While I think [26] is really interesting, I should note that it was done in a not especially long-lived strain of mice, so that is one caveat that should be considered about the results.





[26] Aging Cell. 2008 Aug;7(4):552-60. doi: 10.1111/j.1474-9726.2008.00407.x. Epub

2008 Jul 10.
Mild mitochondrial uncoupling in mice affects energy metabolism, redox balance
and longevity.
Caldeira da Silva CC(1), Cerqueira FM, Barbosa LF, Medeiros MH, Kowaltowski AJ.
Author information: 
(1)Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo,
São Paulo, SP, Brazil.
Caloric restriction is the most effective non-genetic intervention to enhance
lifespan known to date. A major research interest has been the development of
therapeutic strategies capable of promoting the beneficial results of this
dietary regimen. In this sense, we propose that compounds that decrease the
efficiency of energy conversion, such as mitochondrial uncouplers, can be caloric
restriction mimetics. Treatment of mice with low doses of the protonophore
2,4-dinitrophenol promotes enhanced tissue respiratory rates, improved
serological glucose, triglyceride and insulin levels, decrease of reactive oxygen
species levels and tissue DNA and protein oxidation, as well as reduced body
weight. Importantly, 2,4-dinitrophenol-treated animals also presented enhanced
longevity. Our results demonstrate that mild mitochondrial uncoupling is a highly
effective in vivo antioxidant strategy, and describe the first therapeutic
intervention capable of effectively reproducing the physiological, metabolic and 
lifespan effects of caloric restriction in healthy mammals.
PMID: 18505478

There will never be peace in the world while there are animals in our bellies.

#145 Michael R

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Posted 27 March 2016 - 11:59 AM


Tantalizingly, quite a number of studies suggest mitochondrial uncoupling might be associated with increased longevity. Studies [22][23] found that increased UCP-2 expression results in increased longevity in rodents

First, [22][23] are not "studies," but a study [23] and a review covering [22] and related research. Second, [23] did not find that increased UCP-2 increased LS in normal, healthy animals: it found that "The absence of UCP2 shortens lifespan in wild-type mice, and the level of UCP2 positively correlates with the postnatal survival of superoxide dismutase-2 mutant animals." As Michael Rose once said

"Until you show me that you can postpone aging, I don't know that you've done anything," sniffs Michael R. Rose, geneticist at the University of California. "A lot of people can kill things off sooner, by screwing around with various mechanisms, but to me that's like killing mice with hammers -- it doesn't show that hammers are related to aging."

Nor is reducing the severity of the severely-shortened postnatal survival of genetically screwed-up mice anything for normal, healthy people to get excited about.
The authors don't mention their actually relevant results in the abstract, which are that "No difference between survival curves of hUCP2 Tg mice [ie, mice given an extra dose of UCP-2],(n = 14) and WT controls was observed (n = 19, χ2 0.00085, df 1, P > 0.05; Fig. 4B), and mean survival age of hUCP2 mice was not different compared with WT controls [n = 19, 20.93 ± 2.65 vs. 23.95 ± 1.19 mo, not significant (ns)]." In fact, that may be being a little too strict: it may merit noticing that there was a numeric increase in median LS in mice given an extra dose of UCP-2, but without any effect on maximum, and while thre does seem to be some difference in the survival curve, it clearly shows that (a) the curve of the controls was not very rectangular, suggesting there was too much mortality in the controls, likely due to the metabolic morbidity of standard obesogenic lab feeding practices: "Mice and rats were kept under standard laboratory conditions with free access to standard chow food and water" — ie, true, literal ad libitum feeding (and no access to exercise); and (b) even granted that, the advantage came entirely in the first ≈20-22 mo, showing it was entirely related to premature mortality. The null hypothesis is pretty obviously obesity-avoidance — or the authors' own, more stickler's reading of "no difference."

although this result is controversial [24].

(I've intentionally rearranged this in my reply: your original order of wording made it sound as if (24) contrasted with (25), upon which it really doesn't touch: rather, it's related to (23)). It's not actually controversial, since the authors of (23) themselves acknowledge that there's "nothing to see here" in their hUCP2 Tg mice, which is the relevant finding. In any case, (24) is a properly-done LS study on UCP-2-overexpressing mice, with a nice rectangular control survival curve (and their food intake was properly measured, unlike in ((23)), and as I discussed here, it found no effect at all: zip, zero, zilch.

that this is just I and this may be associated with body temperature regulation [25]

I, too, am intrigued by (25), but again, this intervention increased mean but not maximum LS.

Similarly suggestive, [26] found that mice chronically treated with a mild mitochondrial uncoupling agent that works independently of the UCPs (a chemical called 2,4-dinitrophenol or DPN) resulted in mice who ate more, weighed less, had lower measures of fasting glucose, triglycerides, insulin and oxidative damage to DNA, and most importantly, lived longer than controls - mean and maximum (oldest 10%) lifespan were extended by 7% and ~11%, respectively.

This is the usual nonsense of short-lived controls, etc.

[22] Curr Aging Sci. 2010 Jul;3(2):102-12.
Uncoupling protein-2 and the potential link between metabolism and longevity.
Andrews ZB(1).
PMID: 20158496 [PubMed - indexed for MEDLINE]

[23] Am J Physiol Endocrinol Metab. 2009 Apr;296(4):E621-7. doi:
10.1152/ajpendo.90903.2008. Epub 2009 Jan 13.

Uncoupling protein-2 regulates lifespan in mice.
PMCID: PMC2670629
PMID: 19141680 [PubMed - indexed for MEDLINE]

[24] Exp Gerontol. 2008 Dec;43(12):1061-8. doi: 10.1016/j.exger.2008.09.011. Epub 2008
Sep 27.

Characterization of survival and phenotype throughout the life span in UCP2/UCP3
genetically altered mice.

McDonald RB(1), Walker KM, Warman DB, Griffey SM, Warden CH, Ramsey JJ, Horwitz
PMID: 18854208 [PubMed - indexed for MEDLINE]

[25] Science. 2006 Nov 3;314(5800):825-8.

Transgenic mice with a reduced core body temperature have an increased life span.

Conti B(1), Sanchez-Alavez M, Winsky-Sommerer R, Morale MC, Lucero J, Brownell S,
Fabre V, Huitron-Resendiz S, Henriksen S, Zorrilla EP, de Lecea L, Bartfai T.

PMID: 17082459

[26] Aging Cell. 2008 Aug;7(4):552-60. doi: 10.1111/j.1474-9726.2008.00407.x. Epub
2008 Jul 10.
Mild mitochondrial uncoupling in mice affects energy metabolism, redox balance
and longevity.
Caldeira da Silva CC(1), Cerqueira FM, Barbosa LF, Medeiros MH, Kowaltowski AJ.
Free full text: http://onlinelibrary...08.00407.x/epdf

PMID: 18505478

#146 Dean Pomerleau

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Posted 27 March 2016 - 12:13 PM

Thanks Michael,


As I said, the longevity promoting effects of UCP proteins are pretty tentative and controversial, so you are right to be skeptical of positive benefits. But it seems relatively well-supported that extra energy expenditure (and therefore calories metabolized) as a result of higher mitochondrial uncoupling doesn't shorten lifespan, as your "calories, calories, calories" mantra would suggest it should. Right? 


I'll talk more about this in my upcoming post about the newly uncovered Ikeno et al paper, so feel free to hold your response until that post. And of course you are more than welcome in the meantime to go back and comment on either my cold exposure albatross post or the bulk of my sarcolipin post, rather than just the small part of it that focused on mitochondrial uncoupling, which I do appreciate your cogent comments about.



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#147 Dean Pomerleau

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Posted 28 March 2016 - 04:32 PM

Cold Exposure & Exercise Boost Immune System Function and Slows Cancer


I've got two big posts for this thread in the pipeline (on Ikeno et al and on Speakman's body of work). But I had to put those on hold to report on this new study [1], hot off the presses (popular press account). In fact, it's very related to several ongoing threads on these forums, so I think I'll be making several other posts as well to point to this one. It relates to four topics near and dear to our hearts, and germane to this thread - exercise, immune system function, cancer and cold exposure. 


Unlike a lot of the studies we discuss, with many moving parts, this one was relatively straightforward, at least in its results. Researchers divided mice into individual cages, some with running wheels and some without. Unfortunately, they don't report the housing temperature, except to say (in the supplemental material) the mice were housed in a "thermo-stated environment", which I interpret to mean a temperature-controlled room. Since they didn't mention temperature explicitly, it seems almost certain the housing temperature was around 'normal laboratory conditions', i.e. 21-22 °C, which as we know is pretty chilly for mice - more on that below. The mice were allowed to run voluntarily (or not for the control mice) for four weeks. Then the mice were injected with various cancer promoting agents to induce cancer. After the injection, a group of the initially-sedentary mice were given a running wheel, to see how starting exercise after cancer initiation would impact the outcome. All the mice were then monitored to see how their tumor burden and blood chemistry changed over time.


What they found was quite dramatic. Giving mice free access to a running wheel reduced tumor burden by about 60% in both sexes, across range of ages (young, adult, older), and across a variety of different types of cancers, including lung cancer, liver cancer and skin cancer. But only if exercise was performed prior to cancer initiation - picking up the exercise habit after cancer had started didn't help slow tumor growth. And this effect wasn't a result of reduced food intake or weight loss in the exercisers (i.e. crypto-CR). The both sedentary and running mice we given ad lib access to food, and the running mice ate enough to compensate for the calories spent exercising, and so didn't lose weight. In fact, they ended up avoiding the weight loss exhibited by the cancer-ridden sedentary mice, and so weighed slightly more than the sedentary controls by the end of the study.


In short, the mice with access to the running wheel ate more, burned it off with lots of exercise (see below for just how much) so weighed virtually the same, and enjoyed dramatically slower cancer growth and tumor burden than sedentary control mice. Just to be graphic and to show how dramatic the effect was, check out these representative pictures of lung tumors taken from mice in the sedentary (CON - left) and exercise (EX - right) groups (note: the ugly black stuff is the tumor tissue):




So just how much were the mice running? It turns out the answer is a heck of a lot. The male mice in this study ran four miles (6.8 km) per day on the voluntary running wheel. That is virtually an identical distance to the male mice of the same strain in this study [2] (which found exercise increases the growth of new neurons - another great benefit!), which in addition to distance also reported how many minutes per day the mice ran. It turns out that to log 4 miles per day, the mice spend about 550 minutes per day chugging away on the running wheel. That's over 9 hours the mice spent exercising, and is coincidentally almost exactly how much I exercise per day, mostly spent gently pedalling away at my bike desk, which now that I think about it seems quite analogous to a mouse on a running wheel. It's neat when things work out like that.


So what was the mechanism by which cancer was so improved in these chilly little exercise fanatics? That's where things get even more interesting. Through a series of experiments, the researchers determined it was the result of an exercise-induced increase in both epinephrine and Interleukin-6 (IL-6), which in turn boosted the immune systems (specifically, natural killer or NK immune cells) of the running mice so as to attack the cancer. 


This is a cool discover for several reasons. First, the obvious one - it's good to slow the growth of cancer! But also, one concern we've been discussing a lot around here lately (e.g. here and here) is the potential negative impact of CR on immunity, and in particular our ability to fight off infections / invaders after they've gotten a foothold in our bodies. That is exactly the problem this study addresses and appears to provide an answer for. Namely, lots of low-intensity exercise coupled with mild cold exposure appears to dramatically improve the immune system's ability to tag and fight off foreign invaders - in this case cancer cells.


OK you might be saying - maybe I'll buy that nearly continuous, low-intensity exercise is great for boosting important immune system cell types, preventing/slowing cancer and (as a bonus) promoting neurogenesis (e.g. [2]). But besides your inference that the mice in this study were housed at normal lab temperatures and therefore were thermally stressed on top of the exercise, what's the link to cold exposure? 


First off - as we've seen several times in this thread, in studies like Koizumi & Walford (PMID 9032756), and Ikeno et al. (PMID 16424282 - my post about which is in the works, stay tuned...) , mice housed in cool conditions exhibit dramatically less cancer mortality than mice housed at thermoneutrality - i.e. the temperature they are comfortable at. So it's very likely the tumor burden would have been even worse in the sedentary and in the exercising mice if they'd been house in warm conditions rather than the "normal" lab temperature presumably employed in this study.


But what's most relevant and exciting about these results vis a vis cold exposure are the details of the mechanism - i.e. elevated epinephrine and IL-6. Anyone who has been paying attention will know that cold exposure elevates epinephrine. In fact, epinephrine is the primary signalling molecule the body uses to orchestrate its response to cold exposure. I strongly suspect an increase in circulating epinephrine is the likely cause of the increase in resting heart rate (43 → 52 BMP) I've noticed since starting serious cold exposure.


As for interleukin-6, it's funny, in the post where I discuss CE's impact on the immune system, I noticed that PMID: 25338085 found humans who exercised at 0°C exhibited a reduction in a bunch of inflammatory markers, including "Interleukin-2, IL-5, IL-7, IL-10, IL-17, IFN-γ, Rantes, Eotaxin, IP-10, MIP-1β, MCP-1, VEGF, PDGF, and G-CSF", relative to people who exercised at normal room temperature (22 °C). At the time I thought it strange that one of the few interleukins I'd heard of (IL-6) wasn't on the list. It turns out IL-6 is often one of the 'good guys', particularly for muscles, unlike many of the other interleukins, which are pro-inflammatory and implicated in a number of diseases of aging, particularly when chronically elevated. 


In fact, IL-6 isn't just left unchanged by cold exposure - it is increased in both rats [4] and humans. Regarding humans, from that same post, PMID 8925815 found IL-6 was increased (along with bunch of immune system cell types - see the post for the list) in humans as a result of chronic (6 weeks) of cold exposure, and PMID 10444630 found cold exposure after exercise boosts IL-6 levels in humans as well. This study I just uncovered [3], found the same thing - cold exposure after exercise increased (+30%) the already elevated level of IL-6 that resulted from exercise, as opposed to IL-6 dropping precipitously (-69%) when subjects were exposed to warm conditions after exercise. Here is the dramatic graph from [3] showing the post-exercise IL-6 levels in cold and warm subjects during the 90-minutes after exercise:





What's really interesting is the new light these results shed on the mechanism by which cold exposure reduces cancer. Previously I thought (and perhaps Michael did as well) that CE reduced cancer mortality simply by reducing body temperature like CR does, which in turned simply reduced cellular proliferation rate and therefore cancer progression. Sort of like how plants grow more slowly in cold weather - metabolic processes, including cancer growth, just slow down when it's cold. But these results suggest that reduced cancer mortality as a result of CE and/or exercise is likely a result of active upregulation of immune system function, in particularly increased natural killer (NK) cells, triggered by elevated epinephrine and IL-6. In short, this appears to be yet another pathway by which CE can improve health & longevity, both independently and synergistically with exercise. And I can't help but note for Michael's benefit that this beneficial CE pathway is quite independent of "obesity-avoidance".


So what have we learned from all this? I'm tempted to summarize it as "Dean was right"☺. But let me be a little more explicit. The evidence suggests that exercise coupled with cold exposure, or cold exposure alone, can reduce cancer growth and boost important aspects of immune system function (e.g. natural killer or NK cells) by increasing circulating levels of norepinephrine and interleukin-6.


This finding is particularly interesting and relevant given concerns about CR's potential deleterious effects on immunocompetence, and the new human CR study Michael announced a short time ago to investigate the effects of CR on the immune system. I hope I'm not disqualified from participating in the new study as a result of my dietary intake, parts of which Michael characterizes as "stupid high". I'd really like to see how my immune system compares with other CRers. 





[1] Cell Metab. 2016 Mar 8;23(3):554-62. doi: 10.1016/j.cmet.2016.01.011. Epub 2016

Feb 16.

Voluntary Running Suppresses Tumor Growth through Epinephrine- and IL-6-Dependent
NK Cell Mobilization and Redistribution.

Pedersen L(1), Idorn M(2), Olofsson GH(2), Lauenborg B(1), Nookaew I(3), Hansen
RH(4), Johannesen HH(4), Becker JC(5), Pedersen KS(1), Dethlefsen C(1), Nielsen
J(6), Gehl J(7), Pedersen BK(1), Thor Straten P(8), Hojman P(9).

Full text: https://sci-hub.io/1...met.2016.01.011

Regular exercise reduces the risk of cancer and disease recurrence. Yet the
mechanisms behind this protection remain to be elucidated. In this study,
tumor-bearing mice randomized to voluntary wheel running showed over 60%
reduction in tumor incidence and growth across five different tumor models.
Microarray analysis revealed training-induced upregulation of pathways associated
with immune function. NK cell infiltration was significantly increased in tumors
from running mice, whereas depletion of NK cells enhanced tumor growth and
blunted the beneficial effects of exercise. Mechanistic analyses showed that NK
cells were mobilized by epinephrine, and blockade of β-adrenergic signaling
blunted training-dependent tumor inhibition. Moreover, epinephrine induced a
selective mobilization of IL-6-sensitive NK cells, and IL-6-blocking antibodies
blunted training-induced tumor suppression, intratumoral NK cell infiltration,
and NK cell activation. Together, these results link exercise, epinephrine, and
IL-6 to NK cell mobilization and redistribution, and ultimately to control of
tumor growth.

Copyright © 2016 Elsevier Inc. All rights reserved.

PMID: 26895752



[2] BMC Neurosci. 2012 Jun 8;13:61. doi: 10.1186/1471-2202-13-61.

Voluntary wheel running in mice increases the rate of neurogenesis without
affecting anxiety-related behaviour in single tests.
Garrett L(1), Lie DC, Hrabé de Angelis M, Wurst W, Hölter SM.
Author information: 
(1)Institute of Developmental Genetics, Helmholtz Zentrum München, German
Research Center for Environmental Health, Neuherberg/Munich, Germany.
BACKGROUND: The role played by adult neurogenesis in anxiety is not clear. A
recent study revealed a surprising positive correlation between increased anxiety
and elevated neurogenesis following chronic voluntary wheel running and multiple 
behavioural testing in mice, suggesting that adult hippocampal neurogenesis is
involved in the genesis of anxiety. To exclude the possible confounding effect of
multiple testing that may have occurred in the aforementioned study, we assessed 
(1) the effects of mouse voluntary wheel running (14 vs. 28 days) on anxiety in
just one behavioural test; the open field, and (2), using different markers,
proliferation, differentiation, survival and maturation of newly born neurons in 
the dentate gyrus immediately afterwards. Effects of wheel running on
anxiety-related behaviour were confirmed in a separate batch of animals tested in
another test of anxiety, the light/dark box test.
RESULTS: Running altered measures of locomotion and exploration, but not
anxiety-related behaviour in either test. 14 days running significantly increased
proliferation, and differentiation and survival were increased after both running
durations. 28 day running mice also exhibited an increased rate of maturation.
Furthermore, there was a significant positive correlation between the amount of
proliferation, but not maturation, and anxiety measures in the open field of the 
28 day running mice.
CONCLUSIONS: Overall, this evidence suggests that without repeated testing, newly
born mature neurons may not be involved in the genesis of anxiety per se.
PMCID: PMC3504529
PMID: 22682077


[3] J Athl Train. 2012 Nov-Dec;47(6):655-63. doi: 10.4085/1062-6050-47.5.09.

Interleukin-6 responses to water immersion therapy after acute exercise heat
stress: a pilot investigation.
Lee EC(1), Watson G, Casa D, Armstrong LE, Kraemer W, Vingren JL, Spiering BA,
Maresh CM.
Author information: 
(1)Department of Kinesiology, University of Connecticut, 2095 Hillside Road,
U-1110, Storrs, CT 06269-1110, USA. elaine.c.lee@aya.yale.edu
CONTEXT: Cold-water immersion is the criterion standard for treatment of
exertional heat illness. Cryotherapy and water immersion also have been explored 
as ergogenic or recovery aids. The kinetics of inflammatory markers, such as
interleukin-6 (IL-6), during cold-water immersion have not been characterized.
OBJECTIVE: To characterize serum IL-6 responses to water immersion at 2
temperatures and, therefore, to initiate further research into the
multidimensional benefits of immersion and the evidence-based selection of
specific, optimal immersion conditions by athletic trainers.
DESIGN: Controlled laboratory study.
SETTING: Human performance laboratory Patients or Other Participants: Eight
college-aged men (age = 22 ± 3 years, height = 1.76 ± 0.08 m, mass = 77.14 ± 9.77
kg, body fat = 10% ± 3%, and maximal oxygen consumption = 50.48 ± 4.75 mL·kg(-1) 
MAIN OUTCOME MEASURES: Participants were assigned randomly to receive either cold
(11.70°C ± 2.02°C, n = 4) or warm (23.50°C ± 1.00°C, n = 4) water-bath conditions
after exercise in the heat (temperature = 37°C, relative humidity = 52%) for 90
minutes or until volitional cessation.
RESULTS: Whole-body cooling rates were greater in the cold water-bath condition
for the first 6 minutes of water immersion, but during the 90-minute,
postexercise recovery, participants in the warm and cold water-bath conditions
experienced similar overall whole-body cooling. Heart rate responses were similar
for both groups. Participants in the cold water-bath condition experienced an
overall slight increase (30.54% ± 77.37%) in IL-6 concentration, and participants
in the warm water-bath condition experienced an overall decrease (-69.76% ±
CONCLUSIONS: We have provided seed evidence that cold-water immersion is related 
to subtle IL-6 increases from postexercise values and that warmer water-bath
temperatures might dampen this increase. Further research will elucidate any
anti-inflammatory benefit associated with water-immersion treatment and possible 
multidimensional uses of cooling therapies.
PMCID: PMC3499890
PMID: 23182014
[4] Clin Exp Immunol. 2010 Jul 1;161(1):171-5. doi: 10.1111/j.1365-2249.2010.04156.x.
Epub 2010 Apr 29.
The effect of adrenomedullin and cold stress on interleukin-6 levels in some rat 
Yildirim NC(1), Yurekli M.
Author information: 
(1)Tunceli University, Faculty of Engineering, Department of Environmental
Engineering, Tunceli, Turkey. nurancyildirim@tunceli.edu.tr
Stress known to stimulate sympathetic activity, as well as the
hypothalamic-pituitary-adrenal axis (HPA), produces a significant increase in
adrenomedullin (AdM) levels, suggesting a regulatory or protective role for AdM
in countering HPA activation that follows a variety of stressors. Stressors can
modulate the secretion of proinflammatory cytokines. Interleukin (IL)-6 is a
potent activator of the HPA and appears to play a pathogenic role in conditions
related to stress. In the present study, we investigated the administration of
AdM on IL-6 levels in cold exposed rats. Male Wistar rats were divided into four 
groups as control, adrenomedullin treatment, cold stress and cold
stress+adrenomedullin-treated groups. In the adrenomedullin-treated group,
animals received intraperitoneal (i.p.) injection of adrenomedullin (2000 ng/kg
body weight) once a day for a week. For the cold stress exposure the rats were
kept in separate cages at 10 degrees C for a week. Control group rats were kept
in laboratory conditions. The concentration of IL-6 was determined using an
enzyme-linked immunosorbent assay (ELISA) kit. When compared to control, IL-6
levels increased significantly in the cold stress- and adrenomedullin-treated
groups (P<0.05). Administration of AdM in addition to cold stress decreased IL-6 
levels in lung and liver, but increased in brain and heart when compared to
control (P<0.05). The results suggest that cold stress may induce increase of rat
proinflammatory cytokine IL-6 and adrenomedullin may play a regulatory or
protective role for cold stress.
PMCID: PMC2940162
PMID: 20456410 

There will never be peace in the world while there are animals in our bellies.

#148 Dean Pomerleau

Dean Pomerleau
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Posted 29 March 2016 - 03:29 PM

Warm Conditions Impair Human Glucose Metabolism & Insulin Sensitivity


Here is a new one [1] from Al (thanks Al!) that goes in the other direction (i.e. warm rather than cold exposure) with deleterious effects on important markers of health and longevity.


It tested 10 men in two experiments, where each served as their own control by repeating each of the conditions. The men started out fasting before each session began. The conditions were either resting for 40 minutes or a vigorous workout for 40 minutes, at either normal room temperature (22 °C) or warm temperature (31 °C) - making for a total of four different conditions. After each condition men either ate an ad lib meal consisting of unlimited ham and cheese sandwiches (average consumed meal equalled 1000kcal), or a standard oral dose of glucose 75g (300kcal) as part of an oral glucose tolerance test (OGTT). They measured glucose and insulin both during exercise, and after the meal or glucose challenge.


They found that either resting or exercising at warm temperatures resulted in higher serum glucose and higher serum insulin relative to exercising at room temperature. Here are the two most relevant graphs for glucose (left) and insulin (right). Sorry for the interfering overlay...:


xWYVvFA.png   mCsoWtW.png


As you can see, the black bars (warm conditions) are in each case worse (higher) than the corresponding normal temperature conditions. The glucose graph is particularly interesting. The area under the curve for glucose was slightly (non-significantly) lower after exercising than after resting at normal room temperatures. But cumulative glucose level was higher during and after exercising in warm temperatures relative to normal temperature exercise - and in this case the effect was significant. Notice I said during and after exercise. I was particularly surprised to see that glucose was a lot worse during exercise in warm temperatures, as can be seen dramatically in this graph, showing the time course of glucose:




As you can see, exercising in normal temperature conditions resulted in no elevation in glucose during exercise in a fasted state. In contrast, exercising at 31 °C resulted in a significant elevation in glucose during exercise relative to both resting and exercising in normal temperature.


In short, warm conditions appeared to impair glucose metabolism. This dovetails nicely with all the evidence presented previously in this thread pointing out how cold exposure improves glucose metabolism and insulin sensitivity, discussed in detail here. A prime example is [2], which found:


 [Cold exposure] significantly increased resting energy expenditure, whole-body glucose disposal, plasma glucose oxidation, and insulin sensitivity in the BAT(+) group only.


In other words, in people with BAT (likely due to chronic cold exposure), short-term cold exposure improves glucose metabolism and insulin sensitivity. It's unclear whether BAT is causing these improvements in humans directly, or is simply a marker for other cold adaptations (e.g. elevated sarcolipin in muscle cells to burn calories as heat) that are doing the real heavy lifting.


But whatever the mechanism, once again we see that warm is bad and cold is good when it comes to important markers of health and longevity.





[1] Clin Sci (Lond). 2016 Mar 15. pii: CS20150461. [Epub ahead of print]


 Impaired glucose tolerance after brief heat exposure: a randomized crossover

study in healthy young men.
Faure C, Charlot K, Henri S, Hardy-Dessources MD, Hue O, Antoine-Jonville S.
A high demand on thermoregulatory processes may challenge homeostasis,
particularly regarding glucose regulation. This has been understudied,
although it might concern millions of humans. The objective of this project
was to examine the isolated and combined effects of experimental short-term
mild heat exposure and metabolic level on glycoregulation. Two experimental
randomized crossover studies were conducted. Ten healthy young men
participated in study A, which comprised four sessions in a fasting state at
two metabolic levels (rest and exercise at 60% of maximal oxygen uptake for
40 minutes) in two environmental temperatures (warm: 31?C and control:
22?C). Each session ended with an ad libitum meal, resulting in similar
energy intake across sessions. In study B, twelve healthy young men
underwent two 3-hr oral glucose tolerance tests (OGTT) in warm and control
environmental temperatures. Venous blood was sampled at several time points.
In study A, repeated measure ANOVAs revealed higher postprandial serum
glucose and insulin levels with heat exposure. Glycemia following the OGTT
was higher in the warm temperature compared with control. The kinetics of
the serum glucose response to the glucose load was also affected by the
environmental temperature (temperature-by-time interaction, P = 0.030), with
differences between the warm and control conditions evidenced up to 90
minutes after the glucose load (all P < 0.033). These studies provide
evidence that heat exposure alters short-term glycoregulation. The
implication of this environmental factor in the physiopathology of type 2
diabetes has yet to be investigated.
PMID: 26980346
[2] Diabetes. 2014 Dec;63(12):4089-99. doi: 10.2337/db14-0746. Epub 2014 Jul 23.
Brown adipose tissue improves whole-body glucose homeostasis and insulin
sensitivity in humans.
Chondronikola M(1), Volpi E(2), Børsheim E(3), Porter C(3), Annamalai P(4),
Enerbäck S(5), Lidell ME(5), Saraf MK(3), Labbe SM(6), Hurren NM(3), Yfanti C(7),
Chao T(8), Andersen CR(3), Cesani F(9), Hawkins H(10), Sidossis LS(11).
Brown adipose tissue (BAT) has attracted scientific interest as an antidiabetic
tissue owing to its ability to dissipate energy as heat. Despite a plethora of
data concerning the role of BAT in glucose metabolism in rodents, the role of BAT
(if any) in glucose metabolism in humans remains unclear. To investigate whether 
BAT activation alters whole-body glucose homeostasis and insulin sensitivity in
humans, we studied seven BAT-positive (BAT(+)) men and five BAT-negative (BAT(-))
men under thermoneutral conditions and after prolonged (5-8 h) cold exposure
(CE). The two groups were similar in age, BMI, and adiposity. CE significantly
increased resting energy expenditure, whole-body glucose disposal, plasma glucose
oxidation, and insulin sensitivity in the BAT(+) group only. These results
demonstrate a physiologically significant role of BAT in whole-body energy
expenditure, glucose homeostasis, and insulin sensitivity in humans, and support 
the notion that BAT may function as an antidiabetic tissue in humans.
PMCID: PMC4238005
PMID: 25056438

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#149 Dean Pomerleau

Dean Pomerleau
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Posted 29 March 2016 - 04:16 PM

Serotonin Level NOT Decreased by Cold Exposure in Humans


A post by Al on serotonin, thermoregulation and insomnia [1] promoted me to look into the connection. Al's study seemed to suggest that cold exposure may deplete serotonin, and as a result impair sleep, at least in mice. That link suprised me, since I'm finding I'm sleeping better these days since starting cold exposure, despite reducing the temperature in my room while sleeping.


It turns out that while cold exposure does indeed result in a drop in serotonin in rodents, the same (thankfully) doesn't appear to be true in humans, at least not to any large extent. Study [2] found only a small, non-significant drop in circulating serotonin as a result of cold exposure in sixty healthy men:


[N]o significant effects of treatment [including cold exposure - DP] on [Serotonin] activity as indicated by measurements of whole blood and platelet-rich plasma serotonin could be shown.

Nevertheless, the several times I've continued hard-core cold exposure (with my Cool Fat Burner vest) right up until bedtime, I've found my heart rate elevated (likely due to elevated epinephrine) and I had difficulty falling asleep. Difficulty falling asleep is very unusual for me - I usually have trouble staying asleep, a problem that seems to have disappeared since I started serious cold exposure.


So to make sure I can fall asleep, my practice of late has been to back off my degree of cold exposure for an hour or two prior to bedtime. This allows me to drop off to sleep easily. Then, since my bedroom is somewhat chilly, I can continue cold exposure while sleeping soundly, even getting back to sleep easily after my midnight trip to the bathroom.





[1] Sleep. 2015 Dec 1;38(12):1985-93. doi: 10.5665/sleep.5256.


 Insomnia Caused by Serotonin Depletion is Due to Hypothermia.


Murray NM, Buchanan GF, Richerson GB.


Study Objective:

Serotonin (5-hydroxytryptamine, 5-HT) neurons are now thought to promote
wakefulness. Early experiments using the tryptophan hydroxylase inhibitor
para-chlorophenylalanine (PCPA) had led to the opposite conclusion, that
5-HT causes sleep, but those studies were subsequently contradicted by
electrophysiological and behavioral data. Here we tested the hypothesis that
the difference in conclusions was due to failure of early PCPA experiments
to control for the recently recognized role of 5-HT in thermoregulation.


Adult male C57BL/6N mice were treated with PCPA (800 mg/kg intraperitoneally
for 5 d; n = 15) or saline (n = 15), and housed at 20?C (normal room
temperature) or at 33?C (thermoneutral for mice) for 24 h. In a separate set
of experiments, mice were exposed to 4?C for 4 h to characterize their
ability to thermoregulate.

Measurements and Results:

PCPA treatment reduced brain 5-HT to less than 12% of that of controls.
PCPA-treated mice housed at 20?C spent significantly more time awake than
controls. However, core body temperature decreased from 36.5?C to 35.1?C.
When housed at 33?C, body temperature remained normal, and total sleep
duration, sleep architecture, and time in each vigilance state were the same
as controls. When challenged with 4?C, PCPA-treated mice experienced a
precipitous drop in body temperature, whereas control mice maintained a
normal body temperature.


These results indicate that early experiments using para-chlorophenylalanine
that led to the conclusion that 5-hydroxytryptamine (5-HT) causes sleep were
likely confounded by hypothermia. Temperature controls should be considered
in experiments using 5-HT depletion.


PMID: 26194567



[2] Neuropsychobiology. 1993;28(1-2):37-42.

Lowering of body core temperature by exposure to a cold environment and by a
5-HT1A agonist: effects on physiological and psychological variables and blood
serotonin levels.

Rammsayer T(1), Hennig J, Bahner E, von Georgi R, Opper C, Fett C, Wesemann W,
Netter P.

Full text: http://www.karger.co...icle/Pdf/118997

The present study was designed to compare the effects of a pharmacologically
induced decrease in body core temperature to the effects observed with lowering
of body temperature by exposure to a cold environment. Our special interest was
the involvement of 5-HT in thermoregulatory responses. Sixty healthy male
volunteers were randomly assigned to one of the following conditions: exposure to
normal ambient temperature (28 degrees C) and placebo, exposure to cold ambient
temperature (5 degrees C) and placebo, or normal ambient temperature and 10 mg of
the partial 5-HT1A agonist ipsapirone. As indicators of physiological responses
to lowering of body temperature, tympanic temperature, skin temperature, EMA,
metabolic rate, and heart rate were monitored and saliva cortisol levels and
peripheral 5-HT concentrations were determined. In addition, ratings on ambient
temperature, thermal discomfort, and feelings of irritability were obtained.
While lowering of body core temperature was associated with marked
counterregulations (decrease of skin temperature, increase in EMA and metabolic
rate) and feelings of discomfort, this was not observed with ipsapirone. An
increase in cortisol levels was primarily observed in the ipsapirone group and
was not reflected by respective changes in whole blood or platelet 5-HT
indicating that brain and platelet 5-HT are not related.

PMID: 8255408

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#150 Dean Pomerleau

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Posted 30 March 2016 - 07:10 PM

Dean's Comments on Ikeno et al - More Support for "Cool-CR"




Here is my long promised post in reply to Michael's post about Ikeno et al [1], which he seems to interpret as suggesting (to quote Michael):

That's a real puzzler under any "Keep Cool, CRONie!" hypothesis, BAT or otherwise...


[A]bsolute Calories are the key to the anti-aging effect.


First off, I think I understand why a cursory reading of [1] might lead someone to that interpretation. But I aim to show through more careful analysis in this post that Michael is mistaken. In fact, I aim to demonstrate that Ikeno et al [1] shows just the opposite - it provides strong support for the "Cool CR is good for health/longevity" hypothesis, and provides strong evidence against the absolute calories mantra Michael is so fond of.


To accomplish this challenging reversal of Michael's interpretation, I will do a head-to-head comparison between  Ikeno et al [1] with one of the important papers which kicked this whole thread off - Koizumi & Walford [2], discussed previously here and here, which as you'll recall found that the benefits of CR were completely obliterated if the CR mice were housed at a thermoneutral temperature (30 °C) relative to CR at normal lab temperature (21 °C).


I will show the data between the two studies [1] and [2] lines up very consistently, and together the data and insights provided by the two studies support the "cool CR" hypothesis remarkably well. This will be a bit of a complicated story, but I'll walk you through it and I promise the payoff (new insights) at the end will be worth the effort to follow along. 


First, a few assumptions:

  • The housing temperature of [1] is assumed to have been around "normal" lab temperature (21 °C). Why the heck didn't they report housing temperature? This is an egregious oversight on the parts of the authors.  Not only wasn't temperature reported, but it looks like it varied too - since the authors say food intake varied seasonally, likely as a result of temperature variations in the animal housing facility. What the heck - wasn't their colony room temperature controlled!?
Month-to-month variation in food intake was considerable, but was similar in both housing groups. This variation
was probably due to variation in temperature of the colony room, because food intake was inversely related to room
temperature (data not shown).
  • The housing 4 mice per cage in [1] (and thereby permitting the mice to stay warmer by huddling) was approximately thermally equivalent to elevating their housing temperature to about the same as the 30 °C used in [2]. The large impact of group housing on temperature regulation of mice is backed up by [3], which found BAT activity was 50% lower in dual-housed mice relative to mice housed alone. The effect would be even bigger if housed 4-to-a-cage like in [1]. The near equivalence of 4-per-cage housing and 30 °C housing in terms of thermoregulation will be supported directly below in the head-to-head comparison by comparing food intake and body weight, so it's more than just an assumption.
  • Both [1] and [2] used the same mouse strain (C57BL/6J). Therefore their lifespans should be reasonably comparable across studies if the mice were treated the same. 
  • Study [1] used male mice and [2] used female mice. From a large longevity study done [5] on this strain of mice (1000 males & females) to compare male vs. female longevity, it was found that male C57BL/6J live about 100 days longer than female mice on average. So I'm going to spot each group of mice in the Walford [2] study 100 extra days of lifespan to make it a fair lifespan comparison. You'll see once again this us supported by the data.

But before diving into the head-to-head comparison, a couple uncontroversial but important observations from [1] relevant to these discussions:

  • The cool (singly-housed) mice in [1] ate 40% more than "warm" (multiply housed) mice, but weighed the same, as a result of being chilly in single cages rather than being able to huddle. Despite eating 40% more, the cold mice lived just as long as the warm mice. Another example where eating extra calories doesn't reduce health or longevity, as long as it's burned off generating heat. Of course, since they were both (literally) AL-fed, these two groups' longevity wasn't terrific.
  • The cool CR mice in [1] ate the same amount as "warm" CR mice, weighed 20% less and lived the same mean and max lifespan as the warm CR mice. Here once again we see that cold exposure, even when combined with extreme, near-starvation CR - almost 60% restriction (i.e. only 40% as much food) relative to comparable controls (Singly-house AL mice), were able to live as long (both mean and max) lifespan as the warm CR mice. So even when you pound mice with cold-exposure on top of very severe CR, mice still aren't at a lifespan disadvantage relative to warm CR mice. But as I'll show below, you can do even better than lifespan parity with warm CR by cool housing mice and not cutting their calories to the point where the mice are nearly starving.
  • Not only were the cool CR mice in [1] nearly starved of sufficient calories @ 60% CR, they were also likely lacking in other nutrients as well. It was actually a food restriction rather than a calorie restriction experiment. In true and careful CR experiments (e.g. Koizumi & Walford [2] to which I'll compare), the mice in the CR group are fed extra vitamins, minerals and protein to keep their health and lifespan from getting cut short due to nutrient deficits. Study [1] did not take this precaution, and it is quite apparent the cool-house CR mice suffered the consequences, as I'll discuss more below.
  • The cool-housed CR mice were nearly immune to cancer. Only 4% of the cool-housed CR mice died of cancer, while 36% of the warm-housed CR mice died of cancer.
  • The cool-house CR mice in [1] died of infection - 50% died of pneumonia, compared with 10% of the warm-house CR mice, likely due to the poor cool-housed CR mice having a very compromised immune system due to near starvation-level net calorie restriction coupled with frank nutrient deficits. Personally, relative to a high(er) risk of cancers, many types of which have no effective treatment, I'd much prefer a higher risk of a condition I can avoid (pneumonia) via more calories, better nutrition and/or a simple vaccine. So even if my argument below is wrong, and there is an unavoidable tradeoff between lower cancer but higher infections as a result of chronic cold exposure, I still think it's rational to pick cold exposure (i.e. chose higher pneumonia risk over higher cancer risk).

Those are the major takeaway messages - cold exposure didn't hurt, either when the mice were allowed to get fat (feeding AL) or when kept thin. The cold CR mice were virtually immune to the #1 killer of lab rodents - cancer. But they were probably close to starvation and malnourished, and so their immune system was depressed making them unusually susceptible to pneumonia, which is avoidable and treatable in humans.


You may at this point be perfectly reasonable in questioning the above interpretations and conclusions. It's good to be skeptical. But in the following I aim to convince you. 


I will now do a head-to-head comparison between this Ikeno et al study [1] Koizumi & Walford [2], using the following two graphs created from the data in the two papers. A couple comments about the notation in the graphs: 

  • The groups referenced by 'I' (e.g. "Cool AL-I") refer to a group of mice from the Ikeno [1] study.
  • The groups referenced by 'W' (e.g. "Cool AL-W") refer to a group of mice from the Koizumi & Walford [2] study (sorry Koizumi - Roy takes precedence ).
  • The Koizumi & Walford AL mice weren't really fed ad lib - they were 20% restricted relative to AL. We'll see that reflected in the food intake data.
  • When I say 'cool' in reference to a group of mice, it means "housed at normal room temperature (~21 °C) with one mouse to a cage" - this was definitively stated to be the situation in Koizumi & Walford, and is presumed to have been the temperature in Ikeno et al. The food intake and body weight data will indeed strongly suggest this was the case for both groups.
  • When I say 'warm' in reference to a group of mice, it means "housed at 30 °C" in the case of Koizumi & Walford groups, and "housed 4-to-a-cage at normal room temperature" in the case of Ikeno et al groups.
  • Just a reminder - the Koizumi & Walford lifespans have been bumped up by 100 days to account for sex differences in longevity.


OK on to the data. This first graph compares the food intake, body weight and "longest lived 10%" lifespan of the cool-housed control animals in both the Ikeno (I) and Koizumi & Walford (W) studies. 




As you can see, the control animals in the two studies had nearly identical weights (about 40g) and identical sex-adjusted lifespans (1050 days). The Ikeno controls were truly fed AL (35g/wk) while the Walford controls were reportedly fed 20% less that what they would otherwise eat if given free access to food (33g/wk), in order to prevent obesity. 20% less than 33g is 27g/wk. So interestingly, we see that the cool-housed Ikeno control mice ate a lot more, weighed the same, and lived the same as the Walford controls. This suggests if anything the mystery temperature in the Ikeno study was less that the room temperature used in the Walford study. This will come up again in the discussion of the CR conditions below. It also undermines Michael's contention that "it's abolute calories" that counts - since the Ikeno controls ate more, weighed the same and lived just as long as the Walford controls.


The above comparison of the two control groups is mostly to show the relative parity / comparability between the two studies once we adjust for the 100 day lifespan advantage of male mice of this strain. Same weight → same lifespan in the control groups after adjusting for known sex differences in longevity.


Now on to the interesting CR data comparison between the two studies, using the following identically-structured graph:




Now we have 4 sets of columns, representing the food intake, body weight and longevity of four sets of mice - warm and cool-housed mice from both the Ikeno and the Walford studies.


First let's look at the comparison of the "warm" groups from the two studies, in the left two sets of bars. The Ikeno warm-CR group ate a little more, weighed a little more, and lived nearly identical lifespan to the Walford warm-CR group. This data again points against Michael's "calories, calories, calories" hypothesis, since eating more, and even weighing more, didn't lead to a reduced lifespan in the Ikeno warm-CR mice, as that hypothesis would predict.


But things get really interesting when we compare the cool-CR groups from the two studies, in the right two sets of bars, and especially compare them with the warm-CR groups. First look at the cool-CR Ikeno group (Cool CR-I). They ate at least as much as the two warm-CR groups, but weighed significantly less than both of the others and lived just as long as the other two groups. So they weren't at a longevity disadvantage as discussed above.


But further, my contention (as described above), is that this Cool CR-I group was on the verge of starvation / malnutrition as a result of too little food and a deficiency of vitamins/minerals/protein for their cold-boosted metabolic requirements. By my account, because they were kept in the cold, they should have lived longer than the two warm CR groups, but unfortunately their lifespan was cut short by pneumonia due to a malnutrition-induced depressed immune system I talked about above.


Support for this interpretation of the Cool CR-I data comes from the rightmost set of bars - the cool-housed mice in the Walford study (Cool CR-W). Like the Cool CR-I mice, the Cool CR-w mice were kept cold. But unlike the Cool CR-I mice, the Cool CR-W mice were allowed more food (which was also enriched with vitamins, minerals and protein) than the warm CR mice to make up for the extra calories they were burning as a result of cold exposure. As a result, the body weight of the Cool CR-W mice remained close to the weight of the two warm-housed CR groups (~21g), rather than drop into the near-starvation "danger zone" that the Cool CR-I mice fell to (~18-19g). Further support that the Cool CR-I mice were near starvation level is the fact that even the 65% CR mice in the classic W&W paper [4] that adorns the CRS website weighed about 20g, which is more than the poor Cool CR-I mice in [1].


As a result of avoiding malnourishment and immune system suppression, the Cool CR-W mice had a much longer sex-adjusted lifespan - 1450 days compared with ~1250 for the other three CR groups. Like the Cool CR-I mice, very few of the Cool CR-W mice died of cancer - cool housing kicks butt against cancer. Unfortunately the Walford study [2] doesn't break down what the non-cancer causes of death were in their mice. But Walford et al did test immune system status directly and found:


At no age did energy restriction or housing temperature change the percentages of [the counts and ratios in serum, bone marrow and spleen of a bunch of different immune cell types - DP] CD4 + or CD8 + cells, CD4 + /CD8 + ratios, the percentage of Fas positive cells, the percentage of Fas positive CD4 + or the percentage of Fas positive CD8 + cells in bone marrow and spleen.


So in other words, the well-nourished thin (but not emaciated) and cold-exposed mice in Walford's cool CR group (Cool CR-W) had fully functional immune systems, and so avoided the infections than killed the nearly-starving Cool CR-I mice early, and so could take full advantage of the cancer-preventing benefits of cold-exposure, and so lived a lot longer than the warm CR mice in either study, and a lot longer than the cool but starved CR mice in the Ikeno study.


So in short, what this shows is that:

  1. CR in warm temperatures sucks for lifespan relative to cool-CR, because cool-CR does a tremendous job at preventing cancer.
  2. But cool-CR only manifests it's health/longevity advantage if you allow the cool-CR group to eat enough extra calories (and nutrients) to maintain their weight at a "slim" rather than "concentration camp" level, and to allow them to avoid a compromised immune system.

Put another way Cool-CR is good, but it requires eat sufficient extra calories to support both thermogenesis and the anabolic biochemical necessary to synthesize new cells in the immune system, generate new BAT tissue, new bone tissue and increase the number and size of mitochondria in muscle cells (PMID 25713078). A new exciting study about a novel, non-insulin/IGF-1-mediated anabolic pathway that may be involved in this increased maintenance and synthesis resulting from CE will be the topic of my next post.


So in closing, rather than undermining the "cold-exposure + enough calories to remain slim = optimal health & longevity" hypothesis as Michael suggests, a careful reading of Ikeno et al [1], in combination with Walford et al [2], provides strong support for the hypothesis. 





[1] Ikeno Y, Hubbard GB, Lee S, Richardson A, Strong R, Diaz V, Nelson JF. Housing density does not influence the longevity effect of calorie restriction. J Gerontol A Biol Sci Med Sci. 2005 Dec;60(12):1510-7. PubMed PMID: 16424282. 


[2] Mech Ageing Dev. 1996 Nov 29;92(1):67-82.
A tumor preventive effect of dietary restriction is antagonized by a high housing
temperature through deprivation of torpor.
Koizumi A(1), Wada Y, Tuskada M, Kayo T, Naruse M, Horiuchi K, Mogi T, Yoshioka
M, Sasaki M, Miyamaura Y, Abe T, Ohtomo K, Walford RL.
Author information: 
(1)Department of Hygiene, Akita University School of Medicine, Japan.
Energy restriction (ER) has proven to be the only effective means of retarding
aging in mice. The mechanisms of multiplicity of effects of ER on aging remain,
however, fragmentary. ER induces daily torpor, the induction of which is reduced 
by increasing the ambient temperature to 30 degrees C. The effects of preventing 
hypothermia in ER animals were studied in terms of the expected consequences of
ER on survival, disease pattern and a number of physiological parameters in
autoimmune prone MRL/lpr mice and lymphoma prone C57BL, 6 mice. The results
demonstrate that torpor plays a crucial role in the prevention of lymphoma
development but does not have an affect on other aspects of ER, such as
prevention of autoimmune diseases.
PMID: 9032756


[3] Gordon JC. Thermal physiology of laboratory mice: Defining thermoneutrality. Journal of Thermal Biology Volume 37, Issue 8, December 2012, Pages 654–685 

[4] J Nutr. 1986 Apr;116(4):641-54.
The retardation of aging in mice by dietary restriction: longevity, cancer,
immunity and lifetime energy intake.
Weindruch R, Walford RL, Fligiel S, Guthrie D.
We sought to clarify the impact of dietary restriction (undernutrition without
malnutrition) on aging. Female mice from a long-lived strain were fed after
weaning in one of six ways: group 1) a nonpurified diet ad libitum; 2) 85 kcal/wk
of a purified diet (approximately 25% restriction); 3) 50 kcal/wk of a restricted
purified diet enriched in protein, vitamin and mineral content to provide nearly 
equal intakes of these essentials as in group 2 (approximately 55% restriction); 
4) as per group 3, but also restricted before weaning; 5) 50 kcal/wk of a
vitamin- and mineral-enriched diet but with protein intake gradually reduced over
the life span; 6) 40 kcal/wk of the diet fed to groups 3 and 4 (approximately 65%
restriction). Mice from groups 3-6 exhibited mean and maximal life spans 35-65%
greater than for group 1 and 20-40% greater than for group 2. Mice from group 6
lived longest of all. The longest lived 10% of mice from group 6 averaged 53.0 mo
which, to our knowledge, exceeds reported values for any mice of any strain.
Beneficial influences on tumor patterns and on declines with age in T-lymphocyte 
proliferation were most striking in group 6. Significant positive correlations
between adult body weight and longevity occurred in groups 3-5 suggesting that
increased metabolic efficiency may be related to longevity in restricted mice.
Mice from groups 3-6 ate approximately 30% more calories per gram of mouse over
the life span than did mice from group 2. These findings show the profound
anti-aging effects of dietary restriction and provide new information for
optimizing restriction regimes.
PMID: 3958810
[5] J Gerontol. 1975 Mar;30(2):157-62.

Gerontological data of C57BL/6J mice. I. Sex differences in survival curves.

Kunstyr I, Leuenberger HG.

A group of 1,052 C57BL/6J mice (296 males and 756 females) was kept under
well-defined, clean laboratory conditions from the age of 6 weeks until natural
death. The survival curves of males and females (computer-produced 3, 4, and 5
parameter curves, Gompertz curve histogram) were established and shown to follow
a logistic function. The average life-span amounted to 878 plus or minus 10 days
for males and 794 plus or minus 6 days for females
. These values distinctly
exceed comparable values given in the literature. They are attributed to
favorable conditions of animal care and to supposed alterations in genetic
background. A genetic drift in sex-dependent mean survival time occurred in the
genetically unstable C57BL/6J strain between 1966 and 1970. Before this drift,
the males died sooner; after it, they lived longer.

PMID: 1123533

There will never be peace in the world while there are animals in our bellies.

#151 Dean Pomerleau

Dean Pomerleau
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Posted 31 March 2016 - 01:25 PM

More BAT → Better Bone Health


OK - I lied at the end of my last post when I said my next post would be about a new anabolic pathway that cold exposure (CE) employs to build up things like BAT tissue, bone tissue, immune system cells, and mitochondria in muscles. After getting part way through composing the post, I realized I've neglected to post much of the cool evidence that CE is good for building up and maintaining bone mineral quantity, not just quality like we think (hope?) CR is doing. Rather than survey the literature on this myself, I found a really good recent review [1], entitled The "Skinny" on brown fat, obesity, and bone that did the job for me. Here is an extended quote from that paper, along with some commentary and the references it mentions below:


In humans and in animal models, there is a consistent positive association between metabolically active BAT and bone mass, although it remains unclear whether BAT has direct osteogenic effects, or whether bone and BAT are positively correlated with a third factor, such as lean body mass. In humans, the quantity of cold-activated BAT was positively related to bone mineral density (BMD) in young, lean women [2], and to femoral total area, cross-sectional area,and thigh muscle area in men and women across wide ranges of age and BMI [3]. Lee et al.[4] found a positive correlation of active BAT and BMD in female subjects, but not in males, and BAT vol-ume was also a significant predictor of femoral total cross-sectional area and cortical bone area in children and adolescents [5]. In both younger and older subjects, the positive relationship between BAT and bone mass may be mediated by positive effects of muscle tissue on both BAT mass and bone mass [5][4].


Retaining bone mass as well as bone quality "across wide ranges of age and BMI" sounds pretty good right? 


Study [2] was particularly interesting. It included 15 female participants divided into three groups of 5 - anorexic (AN) women (BMI 18.3 - not too anorexic!), recovered anorexic (AN-R) women (BMI 22.4) or health control (HC) women (BMI 21.9 - slimmer than recovered anorexics!).The researchers tested the women's BAT level after overnight cold exposure, and then compared BAT levels with measures of their bone health. They found 80% of HC women had measureable BAT, compared with only 20% of AN and 40% (really only 20% - see graph below) of AN-R women. Once again (like in PMID 23393181 discussed here and here) we see that a history of eating too few calories (perhaps coupled with inadequate nutrition) results in depletion of BAT. But even more interesting, the amount of BAT the women possessed was strongly correlated with their bone mineral density at a number of sites:


Including data of BAT-positive and BAT-negative subjects, there was a positive correlation between BAT and BMD of the femoral neck (r = 0.63; P = 0.01), total hip (r = 0.58; P = 0.02), total body (r = 0.60; P = 0.02), lateral lumbar spine (r = 0.51; P = 0.05), and total lumbar spine (r = 0.67; P = 0.006) (Fig. 2), which remained significant after controlling for BMI and disease status (P = 0.04).


Here is the reference Figure 2:




As you can see, 4 out of 5 AN women (black circles) had zero BAT, and had the lowest BMD in the study. The one AN women who had BAT, had quite a bit, and also had quite good BMD. Similarly for the one women in the AN-R group (red squares) who exhibited significant BAT, i.e. ↑ BAT → ↑ BMD. In the four healthy control women (green triangles) who exhibited BAT, increasing amounts of BAT were associated with increasing BMD in a strikingly consistent relationship. And notice from the quote above, and from this one:


There was no association between BAT and BMI, weight or percent [of Ideal Body Weight] (P = 0.6–0.8).


that BAT content, BMI/weight and BMD were not all tightly correlated together. In particular, women could have a high bone mass despite being thin, as long as they had detectable BAT. The authors end the paper with the following statement:


BAT may be involved in the regulation of stem cell differentiation into the bone lineage at the expense of adipogenesis.


Churning out bone cells rather than fat cells even in thin folks as a result of having BAT sounds darn appealing for skinny CR folks concerned about maintaining bone health.


But you might be saying, couldn't be just a result of the weight loss history of the AN and AN-R women? That is, perhaps the AN and AN-R women were depleted of both BAT and bone mass as a result of past or present severe weight loss and/or poor nutrition. 


A more recent study [3] by the same authors as [2] seems to put that criticism to rest. It found a similar result as seen above in [2] across 19 men and 86 women of various ages (19-77) and BMIs (15.7 - 48.9):


There were positive correlations between BAT volume and total femoral CSA [cross sectional area] and cortical CSA, independent of age, BMI and history of malignancy (P<0.05)... When total femoral CSA was entered as a dependent variable and BAT volume, age and BMI as independent variables in a forward stepwise regression model, BAT volume was the only predictor of total femoral CSA. When femoral cortical CSA was entered as a dependent variable and BAT volume, age and BMI as independent variables, BAT volume was the only predictor of femoral cortical CSA.


OK you say, but [2] was all women and [3] had only 19 men vs 86 women. Is this positive BAT-bone connection just a girl thing? Nope:


Separate analyses in men and women showed more BAT in men and stronger correlations between femoral structure and BAT in men compared to women, despite smaller number of male subjects in our study. This suggests that the BAT-bone connection might be stronger in men.


The same positive correlation between BAT and bone health was observed across 40 children and teenagers as well [5]:


Multiple regression analyses indicated that the volume of BAT predicted femoral cross-sectional area and cortical bone area, even after accounting for height, weight, and gender.


In summary, once again we see having BAT correlates with an important health / longevity benefit - in this case increased bone mass, independent of body weight. As the authors of [1] say, it's unclear whether BAT is causally involved in improved bone health or simply correlated with it remains to be determined. I'd say it's likely to be something in the metabolic program induced by cold exposure, but more on that in my next post.


This positive BAT-bone connection is particularly exciting because increased bone mass is not just a health benefit that CR fails to offer, CR actually results in dramatically reduced bone mineral density. Despite some promising hints that CR bones may be lighter but not more brittle, reduced bone mass remains a serious concern for many of us and has been the downfall of at least one former CR veteran


This is one more reason it makes sense to consider combining one's practice of CR with cold exposure.


I promise in my next post to address the metabolic pathway that might allow this sort of anabolic activity without requiring increased insulin, IGF-1 or any of the other usual growth-promoting agents, the elevation of which can have serious downsides for health & longevity. [Sorry - it wasn't my next post, but here is a link to it].





[1] Am J Phys Anthropol. 2015 Feb;156 Suppl 59:98-115. doi: 10.1002/ajpa.22661. Epub 

2014 Nov 11.
The "Skinny" on brown fat, obesity, and bone.
Devlin MJ(1).
The discovery that metabolically active brown fat is present in humans throughout
ontogeny raises new questions about the interactions between thermoregulatory,
metabolic, and skeletal homeostasis. Brown adipose tissue (BAT) is distinct from 
white adipose tissue (WAT) for its ability to burn, rather than store, energy.
BAT uniquely expresses uncoupling protein-1 (abbreviated as UCP1), which diverts 
the energy produced by cellular respiration to generate heat. While BAT is found 
in small mammals, hibernators, and newborns, this depot was thought to regress in
humans during early postnatal life. Recent studies revealed that human BAT
remains metabolically active throughout childhood and even in adulthood,
particularly in response to cold exposure. In addition to the constitutive BAT
depots present at birth, BAT cells can be induced within WAT depots under
specific metabolic and climatic conditions. These cells, called inducible brown
fat, "brite," or beige fat, are currently the focus of intense investigation as a
possible treatment for obesity. Inducible brown fat is associated with higher
bone mineral density, suggesting that brown fat interacts with bone growth in
previously unrecognized ways. Finally, BAT may have contributed to climatic
adaptation in hominins. Here, I review current findings on the role of BAT in
thermoregulation, bone growth, and metabolism, describe the potential role of BAT
in moderating the obesity epidemic, and outline possible functions of BAT across 
hominin evolutionary history.
© 2014 American Association of Physical Anthropologists.
PMID: 25388370
[2] J Clin Endocrinol Metab. 2012 Apr;97(4):E584-90. doi: 10.1210/jc.2011-2246. Epub 
2012 Jan 18.
Young women with cold-activated brown adipose tissue have higher bone mineral
density and lower Pref-1 than women without brown adipose tissue: a study in
women with anorexia nervosa, women recovered from anorexia nervosa, and
normal-weight women.
Bredella MA(1), Fazeli PK, Freedman LM, Calder G, Lee H, Rosen CJ, Klibanski A.
CONTEXT: Anorexia nervosa (AN) is associated with depletion of body fat, loss of 
bone mineral density (BMD), and impaired thermogenesis. Brown adipose tissue
(BAT) is lower in obese individuals and decreases during aging. Recent studies
have suggested a link between BAT and bone metabolism.
OBJECTIVE: Our objective was to investigate the presence and quantity of BAT in
patients with AN, recovered AN (AN-R), and normal-weight controls and to study
the relationship between BAT and BMD and body composition and investigate
hormonal predictors of BAT.
DESIGN AND SETTING: This was a cross-sectional study at a clinical research
PATIENTS: Patients included 15 women: five with AN (mean age 30 ± 6.3 yr), five
AN-R, and five healthy nonobese controls of comparable age.
MAIN OUTCOME MEASURES: Cold-activated BAT was determined by
fluorodeoxyglucose-positron emission tomography/computed tomography. BMD of
total-body, spine, and hip, fat and lean mass was determined by dual-energy x-ray
absorptiometry. Single-slice magnetic resonance imaging at L4 was done for
abdominal fat compartments, and preadipocyte factor-1 (Pref-1), T₃, and T₄ were
RESULTS: Within the AN group, one of five; in the AN-R group, two of five; and in
the healthy nonobese control group, four of five subjects were BAT positive.
Subjects were divided into groups based on the presence (n = 7) or absence (n =
8) of BAT. Both groups were of comparable age and body mass index. Women with BAT
had higher total-body BMD, higher T₃, and lower Pref-1 compared with women
without BAT. There was a positive correlation between BAT and BMD that remained
significant after controlling for disease status and body mass index.
CONCLUSION: Young women with AN have low cold-activated BAT, which may be due to 
impaired BAT thermogenesis. Young women with BAT have higher BMD and lower Pref-1
compared with women without BAT, suggesting that BAT may be involved in the
regulation of stem cell differentiation into the bone lineage at the expense of
PMCID: PMC3319179
PMID: 22259053
[3] Bone. 2014 Jan;58:55-8. doi: 10.1016/j.bone.2013.10.007. Epub 2013 Oct 17.

Positive effects of brown adipose tissue on femoral bone structure.

Bredella MA(1), Gill CM, Rosen CJ, Klibanski A, Torriani M.

Free full text: http://www.ncbi.nlm....les/PMC3855336/

PURPOSE: Recent studies suggest a link between brown adipose tissue (BAT) and
bone. The purpose of our study was to investigate the effects of BAT on femoral
bone structure.
MATERIALS AND METHODS: We studied 105 patients (19 m, 86 f. mean age 45.5±16.1
years) who underwent F18-FDG positron emission tomography/computed tomography
(PET/CT) for benign etiologies (n=20) or follow-up of successfully treated
malignancies (n=85); mean time between PET/CT and last form of treatment was
14.8±18.0 months. BAT volume by PET/CT; femoral bone structure by CT (total
femoral cross-sectional area (CSA), cortical CSA); and thigh muscle CSA and thigh
subcutaneous fat CSA by CT was assessed.
RESULTS: There were positive correlations between BAT volume and total femoral
CSA and cortical CSA, independent of age, BMI and history of malignancy (p<0.05).
BAT volume correlated positively with thigh muscle CSA and thigh fat CSA
(p<0.05). When total femoral CSA was entered as a dependent variable and BAT
volume, age and BMI as independent variables in a forward stepwise regression
model, BAT volume was the only predictor of total femoral CSA. When femoral
cortical CSA was entered as a dependent variable and BAT volume, age and BMI as
independent variables, BAT volume was the only predictor of femoral cortical CSA.
CONCLUSION: BAT volume is a positive predictor of femoral bone structure and
correlates positively with thigh muscle and subcutaneous fat, possibly mediated
by muscle. These results provide further evidence of a positive effect of BAT on

© 2013.

PMCID: PMC3855336
PMID: 24140784



[4] Osteoporos Int. 2013 Apr;24(4):1513-8. doi: 10.1007/s00198-012-2110-y. Epub 2012 

Aug 14.
Cold-activated brown adipose tissue is an independent predictor of higher bone
mineral density in women.
Lee P(1), Brychta RJ, Collins MT, Linderman J, Smith S, Herscovitch P, Millo C,
Chen KY, Celi FS.
In animals, defective brown adipogenesis leads to bone loss. Whether brown
adipose tissue (BAT) mass relates to bone mineral density (BMD) in humans is
unclear. We determined the relationship between BAT mass and BMD by
cold-stimulated positron-emission tomography (PET) and dual-energy X-ray
absorptiometry (DXA) in healthy volunteers. Higher BAT mass was associated with
higher BMD in healthy women, but not in men, independent of age and body
composition.INTRODUCTION: Contrary to the traditional belief that BAT is present 
only in infants, recent studies revealed significant depots of BAT present in
adult humans. In animals, defective brown adipogenesis leads to bone loss. While 
white adipose tissue mass is a known determinant of BMD in humans, the
relationship between BAT and BMD in humans is unclear. We thus examined the
relationship between BAT and BMD in healthy adults.
METHODS: BAT volume (ml) and activity (standard uptake value) were determined by 
18F-fluorodeoxyglucose PET after overnight mild cold exposure at 19 °C, and BMD
was determined by DXA.
RESULTS: Among 24 healthy adults (age 28±1 years, F=10), BAT volumes were
82.4±99.5 ml in women and 49.7±54.5 ml in men. Women manifested significantly
higher BAT activity, by 9.4±8.1% (p=0.03), than men. BAT volume correlated
positively with total and spine BMD (r2=0.40 and 0.49, respectively, p<0.02) in
women and remained a significant predictor after adjustment for age, fat, and
lean body mass (p<0.05). Total and spine BMD were higher in women who harbored
visually detectable BAT on PET images than those without by 11±2% (p=0.02) and
22±2% (p<0.01), respectively. No associations were observed between BAT
parameters and BMD in men.
CONCLUSIONS: This study demonstrated higher BMD among healthy women with more
abundant BAT, independent of age and other body compositional parameters. This
was not observed in men. The data suggest that brown adipogenesis may be
physiologically related to modulation of bone density.
PMID: 22890364
[5] J Clin Endocrinol Metab. 2012 Aug;97(8):2693-8. doi: 10.1210/jc.2012-1589. Epub
2012 May 16.
Brown adipose tissue and its relationship to bone structure in pediatric
Ponrartana S(1), Aggabao PC, Hu HH, Aldrovandi GM, Wren TA, Gilsanz V.
Author information: 
(1)Department of Radiology, Viterbi School of Engineering, University of Southern
California, Los Angeles, California 90027, USA.
CONTEXT: Emerging evidence suggests a possible link between brown adipose tissue 
(BAT) and bone metabolism.
OBJECTIVE: The objective of this study was to examine the relationships between
BAT and bone cross-sectional dimensions in children and adolescents.
DESIGN: This was a cross-sectional study.
SETTING: The study was conducted at a pediatric referral center.
PATIENTS: Patients included 40 children and teenagers (21 males and 19 females)
successfully treated for pediatric malignancies.
INTERVENTIONS: There were no interventions.
MAIN OUTCOME MEASURES: The volume of BAT was determined by
fluorodeoxyglucose-positron emission tomography/computed tomography. Measures of 
the cross-sectional area and cortical bone area and measures of thigh musculature
and sc fat were determined at the midshaft of the femur.
RESULTS: Regardless of sex, there were significant correlations seen between BAT 
volume and the cross-sectional dimensions of the bone (r values between 0.68 and 
0.77; all P ≤ 0 .001). Multiple regression analyses indicated that the volume of 
BAT predicted femoral cross-sectional area and cortical bone area, even after
accounting for height, weight, and gender. The addition of muscle as an
independent variable increased the predictive power of the model but
significantly decreased the contribution of BAT.
CONCLUSIONS: The volume of BAT is positively associated with the amount of bone
and the cross-sectional size of the femur in children and adolescents. This
relation between BAT and bone structure could, at least in part, be mediated by
PMCID: PMC3410267
PMID: 22593587

There will never be peace in the world while there are animals in our bellies.

#152 Gordo

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Posted 01 April 2016 - 12:33 AM

Dean - regarding your "Ikeno et al" analysis, that is very much in line with what my thoughts were when I read it, and I was right in thinking you would do a much better job of analyzing and articulating it than I could, thanks once again for all the work. I'm tempted to send your analysis to Professor A. Richardson but I have a feeling he won't respond <_<.  I wonder what the best way is to get researchers to improve on otherwise sloppy CR research? 


At any rate, CE just keeps looking better and better.  Hope you don't give yourself hypothermia though!

That graph you posted showing blood glucose comparisons between warm/cold exposed individuals is also remarkable, and aligns with my personal observations/anecdotes so far with CE.  CE is a game changer as far as I'm concerned, and I expect it to change the way CR is practiced.  





Edited by Gordo, 01 April 2016 - 12:44 AM.

#153 Dean Pomerleau

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Posted 01 April 2016 - 03:15 AM

Hi Gordo,
I'm glad someone (other than me) has found some of my analysis useful! I too am quite excited about the potential for CE to improve upon the benefits of CR.
Hope you don't give yourself hypothermia though!


It seems quite the contrary based on personal experience. In particular, I find myself like Eric in the CoolFatBurner.com videos, becoming more and more comfortable in colder and colder conditions everyday. My body is clearly adapting to the cold. At this moment, I'm pedalling away on my stationary bike at a very modest pace (my heart rate is 91 BMP) wearing just bike shorts. The ambient temperature is 62 degF here in my basement, and I've got 3 fans blowing on me. And I'm still feeling a bit on the warm side.


The other thing I've noticed is improved aerobic capacity during exercise. I live in a very hilly neighborhood and I used to get somewhat winded and my legs got tired running up several of the big hills during my twice daily runs. Now I feel much more aerobicly strong. I'm not eating any more or gaining any weight. And I haven't changed my exercise routine either.


I thought it might be a result of an increase in blood oxygen carrying capacity, but I just had a CBC blood test done as a followup to my Dr's concern at my yearly checkup a few months ago that I might be borderline anemic (despite no symptoms). My latest hemoglobin was 13.2 g/dl, right at the bottom of the reference range, as was my ferritin (30 ng/dl). So it would appear my blood's oxygen carrying capacity and iron stores hasn't changed much, although they are up a bit from my last round of tests. 


The only other significant change in my CBC was my white blood cell count (WBC) went up to 4.5, into the low end of the reference range (4.0 - 10.5). This seems like it could be a sign of the improved immunocompetence induced by CE with adequate calories that I talked about as being the advantage enjoyed by the Walford cold mice. The Walford CE+CR mice ate enough calories to keep their immune system counts adequate, enabling them to avoid pneumonia and thereby live longer than both the Walford's warm-CR mice and longer than the starved and therefore immunocompromised CE+CR mice in the Ikeno et al study discussed above. I'm hoping I'm like one of those Walford CE+CR mice!


Regarding my apparent improvements in aerobic capacity, I can only speculate that it may be a result of an increase in mitochondria in my muscles, like was observed as a result of cold exposure in the study I discussed several posts back in my big sarcolipin post.


It's pretty cool (pun intended) to the see apparent parallels between my own experience and the research on cold exposure.



There will never be peace in the world while there are animals in our bellies.

#154 Dean Pomerleau

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Posted 01 April 2016 - 11:34 AM

I was amused and interested to come across this inspirational Under Armor "Rule Yourself" video of Michael Phelps' grueling training regime leading up to his bid for more Olympic gold in 2016, while reading this article on new studies that show better late life fitness (as measured quantitatively by leg strength) is associated with a reduced rate of cognitive decline.


What caught my eye was that at exactly 28sec into the video Michael can be seen throwing ice into a bathtub and then shivering while sitting in the tub at second 29. Don't blink or you'll miss it.



Of course, in seconds 30-32 Michael can be seen stuffing his face with what looks like eggs and french toast. Phelps is famous (or infamous) for reporting he eats about 12K calories per day when in heavy training. And I though ate a lot. The following video shows what he eats in a day. Pretty amazing quantity, most of it crap, including this breakfast:


NBC commentator Bob Costas rattled off Phelps' breakfast menu, which includes three sandwiches of fried eggs, cheese, lettuce, tomato, fried onions, mayonnaise, an omelet, a bowl of grits, three slices of French toast with powdered sugar, and three chocolate-chip pancakes. Without knowing the exact details of the portions, recipes, and ingredients, this meal probably contains roughly 3,000 calories, 



Later Phelps denied eating quite that much in the runup to Beijing, but he certainly ate a lot, and a lot of crap, while remaining amazingly thin:




Part of the reason he could eat so much and not get fat has to do with the number of miles he swims. But it also likely resulted from the huge amount of thermogenesis required to stay warm in a cold pool (water is a much better conductor of heat than air, so it sucks the heat out of a swimmer), and (if the above video is accurate) in the ice baths he takes.


He's an amazing example of a person pushing the envelope of human possibility. I admire the heck out of his athletic accomplishments, although some of his personal mistakes outside the pool have been troubling and hard to watch. But I'd say don't try that at home...



There will never be peace in the world while there are animals in our bellies.

#155 AlPater

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Posted 01 April 2016 - 06:51 PM

Just a couple of quick notes on your most recent blood test results, Dean,


Your resting heart rate went up.


Neutrophil:lymphocyte ratio marker of inflammation went south.



Neutrophil:lymphocyte ratio is positively related to type 2 diabetes in a large-scale adult population: a Tianjin Chronic Low-Grade Systemic Inflammation and Health cohort study.
Guo X, Zhang S, Zhang Q, Liu L, Wu H, Du H, Shi H, Wang C, Xia Y, Liu X, Li C, Sun S, Wang X, Zhou M, Huang G, Jia Q, Zhao H, Song K, Niu K.
Eur J Endocrinol. 2015 Aug;173(2):217-25. doi: 10.1530/EJE-15-0176. Epub 2015 May 7.
PMID: 25953830
It is widely known that inflammation is related to type 2 diabetes (T2D), but few studies have shown a direct relationship between the immune system and T2D using a reliable biomarker. Neutrophil:lymphocyte ratio (NLR) is an easy-to-analyze inflammation biomarker, but few studies have assessed the relationship between NLR and T2D. In order to evaluate how NLR is related to T2D, we designed a large-scale cross-sectional and prospective cohort study in an adult population.
Participants were recruited from the Tianjin Medical University General Hospital-Health Management Centre. Both a baseline cross-sectional (n=87,686) and a prospective (n=38,074) assessment were performed. Participants without a history of T2D were followed up for ∼ 6 years (with a median follow-up of 2.7 years). Adjusted logistic and Cox proportional hazards regression models were used to assess relationships between the quintiles of NLR and T2D (covariates: age, sex, BMI, smoking status, drinking status, hypertension, hyperlipidemia, and family history of cardiovascular disease, hypertension, hyperlipidemia, or diabetes).
The prevalence and incidence of T2D were 4.9% and 6.8/1000 person-years respectively. The adjusted odds ratio and hazard ratio (95% CI) of the highest NLR quintile were 1.34 (1.21, 1.49) and 1.39 (1.09, 1.78) (both P for trend <0.01) respectively as compared to the lowest quintile of NLR. Leukocyte, neutrophil, and lymphocyte counts do not significantly predict the eventual development of T2D.
The present study demonstrates that NLR is related to the prevalence and incidence of T2D, and it suggests that NLR may be an efficient and accurate prognostic biomarker for T2D.

#156 Dean Pomerleau

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Posted 02 April 2016 - 03:03 AM

Thanks for commenting Al.


You wrote:

 Your resting heart rate went up.

Yes, I've pointed that out that my resting heart rate has gone up several times recently (e.g. here), suggesting it's likely a result of an increase in epinephrine as a result of cold exposure. I didn't feel the need to mention it again when talking about my blood test.


Neutrophil:lymphocyte ratio marker of inflammation went south. [citing PMID 25953830 which found N:L to be a marker for low-grade inflammation and predictive of future diabetes development in a population of Chinese people]

You have got to be kidding Al. As I said, my WBC count went from well below the bottom end of the reference range to the low end of the reference range (4.5  RR 4.0 - 10.5).


As I also suggested, this seems more likely a case of building my immunocompetence as a result of cold exposure boosting my immune system rather than a sign of low-grade systemic inflammation. In fact it continues to surprise me how little inflammation I appear to experience - e.g. a complete lack of aches, pains or sore joints despite engaging in (admittedly low-impact & low-intensity) exercise over 9 hours per day, 7 days per week.


Regarding signs of diabetes. I just happened to do fasting and post-meal glucose tests yesterday and this morning. My fast glucose was 86 mg/dl. Ten minutes after completing my 3400+ kcal single daily meal, my glucose was 120 mg/dl. Fifteen minute later, after a chilly one mile run, my glucose was 107 mg/dl. I'd say I'm doing just fine in the glucose control department, and am at quite low risk of diabetes.



There will never be peace in the world while there are animals in our bellies.

#157 Dean Pomerleau

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Posted 02 April 2016 - 01:09 PM

An Eco-Evolutionary Explanation for Synergistic Effects of CR and CE




Consider this post a prelude and gentle introduction to my next post, which will be pretty technical in nature on the topic of metabolic pathways associated with CR & CE. Here I'm going to set the stage for that discussion.


I've long thought it helpful to think about the evolutionary explanation for the CR longevity effect. In summary, the idea is that during times of food shortage, mammals with genetic machinery that enables them to 'hunker down' and survive the famine by shifting scare caloric resources to bodily maintenance & repair, rather than growth and reproduction, would have a reproductive advantage and so such an adaptive metabolic program would become entrenched in the genes of our ancestors over time, and would still be part of our evolutionary endowment.


What I came to realize while researching the metabolic pathways of CR & CE is that chronic food shortage and chronic cold exposure would likely have occurred simultaneously with the seasons as our mammalian ancestors spread into new, less-hospitable niches after the extinction of the dinosaurs. In particular, consider what happens in winter everywhere except the tropics. It gets colder. What happens when it gets colder? Homeotherms need to spend more calories generating heat and food becomes more scarce, both because plants stops growing when it's cold, other animals hibernate or migrate and so aren't as readily available as food sources, and stores of food you've built up, either literally (e.g. squirrels & acorns) or as excess body fat, become depleted.


At such times the two stressors (cold & food shortage) would even be mutually reinforcing. A shortage of food in winter would force you to leave the relative warmth of your burrow or cave and venture out in search of food, exposing you to more cold. Depleting of your insulating fat stores as a result of wintertime food shortage would also increased thermogenic requirements. And the cooler ambient temperatures, your increased exposure to them via more foraging, and your reduced insulation would increase your calorie needs in order to support the greater physical activity and thermogenesis, thereby exacerbating your net calorie deficit. In other words, a calorie deficit leads to more cold exposure which leads to a greater calorie deficit.


If CR & CE co-occurred regularly, repeatedly and over sufficiently long stretches of our evolutionary history, I suggest it would make evolutionary sense for metabolic adaptations to the two stresses to work synergistically with one another to optimize an organism's chance of survival. In fact, if the two occurred with high enough correlation (e.g. every winter organisms face both starvation and hypothermia), the adaptation to both stresses could be considered a single package, for example filling in each other's gaps in order to tune to body's metabolism to maximize its chance of surviving. The body would come to assume CR & CE will occur simultaneously, and tune its metabolic response based on the combination of the two.


In modern times, with the advent of central heating and corner grocery stores, food shortages and cold exposure have become entirely avoidable, and separable. It's possible these days to have one without the other. In fact, many CRers do just that, restricting calories but eschewing the cold, on the assumption that, in the immortal words of (or will it be "words of immortal"?) Michael "absolute Calories are the key to the anti-aging effect," and so if I'm exposed to cold, I'll have to eat more calories and that will erase CR's benefits.

As discussed repeatedly in this thread, there are several lines of evidence that seem to directly contradict Michael's perspective on this, and instead support the idea that the health/longevity benefits of CR and CE are inextricably linked. First, it's easy to overlook the fact that virtually every CR rodent study ever conducted has combined CR & CE, by housing rats & mice singly at normal room temperature (~21 °C) whereas thermoneutrality for isolated rodents is ~30 °C. It is the rare exceptions to this co-occurrence of CR & CE in the CR literature that are informative and provide support for the thesis that CR & CE are co-dependent. They are, quite literally, the exceptions that prove the rule.
The classic example is the famous Holloszy (1985) "rats with cold feet" study [1] that kicked off this whole thread. Holloszy found that rats given ad lib access to food ate 44% more, weighed a bit less and live a bit longer than control mice kept at 'normal' housing temperatures, which we know are actually pretty chilly for rodents already. The cold rats were less than half as susceptible to cancer as the warmer rats, a benefit of cold exposure we've seen repeatedly in the literature discussed in this thread.  Ikeno et al [2] (discussed here) found almost the same thing, but even more cleanly, in their ad lib fed controls. Cold exposed (i.e. singly housed) ad lib mice ate 40% more, weighed almost exactly the same, and had an identical lifespan to warm (multiply-housed) ad lib mice.


What the Holloszy and Ikeno studies show is that cold exposure alone, without a large net deficit in calories (i.e. a net deficit that leaves the organism CR-thin) doesn't reduce health or longevity, and in fact it may increase health/longevity somewhat, e.g. by preventing cancer. But without a large net deficit in calories, cold exposure alone doesn't increase lifespan either. To get large health and lifespan benefits, CE needs to be combined with CR, in the form of a net calorie deficit sufficient to dramatically reduce body weight below normal. Alone CE doesn't cut it.


Conversely, Koizumi & Walford [3], found that CR without CE doesn't work either. Warm-housed CR mice didn't live any longer on average than cool-housed, ad lib fed controls, while cool-housed CR mice (who were fed more than warm-housed CR mice to maintain an identical body weight) lived a lot longer, largely again because they avoided cancer, unlike the warm-housed CR mice who were as cancer-prone as the controls.


What the Koizumi & Walford study shows is that CR, and the severe reduction in body weight that accompanies it, doesn't reduce health or longevity relative to controls. But without cold exposure, calorie restriction alone doesn't increase lifespan either. To get large health and lifespan benefits, CR needs to be combined with CE. Alone CR doesn't cut it.  


A final, sad example of a study where CR & CE were decoupled with unfortunate results was the CR monkey study. As discussed here, the NIA monkeys (who, unlike the UW monkeys, were a real test of whether CR works or not relative to a healthy, obesity-avoiding diet) were housed at an average daily temperature that was above thermoneutrality. And we all know the disappointing upshot, the NIA monkeys did not live longer than controls, despite eating significantly fewer calories, and being thinner throughout their lives. Once again we see that CR without CE doesn't work.


In short, the evidence strongly suggests that CR & CE are a package deal. You can't get substantial benefits from one without the other. You can't be thin and warm and expect to live a long time. You can't be chubby and cold and expect to live a long time. Thin and cold is what it takes.


I tried to argue above that this coupling makes sense from an evolutionary perspective. CR & CE were likely to co-occur on such a regular and consistent basis in our evolutionary history that the body's of our ancestors became tuned for maximal survival under the assumption that both would be present. And so one without the other fails to elicit the complete set of complex and complementary metabolic adaptations required to extend health and lifespan.


In my next post I promise to (finally) delve into an example of how this sort of complementarity between CR & CE manifests itself.





[1] J Appl Physiol (1985). 1986 Nov;61(5):1656-60.

Longevity of cold-exposed rats: a reevaluation of the "rate-of-living theory".
Holloszy JO, Smith EK.
It has been postulated that increased energy expenditure results in shortened
survival. To test this "rate-of-living theory" we examined the effect of raising
energy expenditure by means of cold exposure on the longevity of rats. Male
6-mo-old SPF Long-Evans rats were gradually accustomed to immersion in cool water
(23 degrees C). After 3 mo they were standing in the cool water for 4 h/day, 5
days/wk. They were maintained on this program until age 32 mo. The cold exposure
resulted in a 44% increase in food intake (P less than 0.001). Despite their
greater food intake, the cold-exposed rats' body weights were significantly lower
than those of control animals from age 11 to 32 mo. The average age at death of
the cold-exposed rats was 968 +/- 141 days compared with 923 +/- 159 days for the
controls. The cold exposure appeared to protect against neoplasia, particularly
sarcomas; only 24% of the necropsied cold-exposed rats had malignancies compared
with 57% for the controls. The results of this study provide no support for the
concept that increased energy expenditure decreases longevity.
PMID: 3781978
[2] Ikeno Y, Hubbard GB, Lee S, Richardson A, Strong R, Diaz V, Nelson JF. Housing density does not influence the longevity effect of calorie restriction. J Gerontol A Biol Sci Med Sci. 2005 Dec;60(12):1510-7. PubMed PMID: 16424282. 
[3] Mech Ageing Dev. 1996 Nov 29;92(1):67-82.
A tumor preventive effect of dietary restriction is antagonized by a high housing
temperature through deprivation of torpor.
Koizumi A(1), Wada Y, Tuskada M, Kayo T, Naruse M, Horiuchi K, Mogi T, Yoshioka
M, Sasaki M, Miyamaura Y, Abe T, Ohtomo K, Walford RL.
Author information: 
(1)Department of Hygiene, Akita University School of Medicine, Japan.
Energy restriction (ER) has proven to be the only effective means of retarding
aging in mice. The mechanisms of multiplicity of effects of ER on aging remain,
however, fragmentary. ER induces daily torpor, the induction of which is reduced 
by increasing the ambient temperature to 30 degrees C. The effects of preventing 
hypothermia in ER animals were studied in terms of the expected consequences of
ER on survival, disease pattern and a number of physiological parameters in
autoimmune prone MRL/lpr mice and lymphoma prone C57BL, 6 mice. The results
demonstrate that torpor plays a crucial role in the prevention of lymphoma
development but does not have an affect on other aspects of ER, such as
prevention of autoimmune diseases.
PMID: 9032756

There will never be peace in the world while there are animals in our bellies.

#158 AlPater

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Posted 02 April 2016 - 07:38 PM

Thanks for the explanation of your increased heart rate.  I had thought the lower the better for a healthy young/middle-aged man.


A search http://www.ncbi.nlm....atio all-cause*shows that the ratio relates to the inflammation marker's influences and the risks of many different conditions.

#159 Dean Pomerleau

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Posted 03 April 2016 - 08:43 AM


A search http://www.ncbi.nlm....atio all-cause*shows that the ratio relates to the inflammation marker's influences and the risks of many different conditions.


A quick search on "low white blood cell count" will bring up any number of negative health outcomes associated with too few white blood cells including cancer, autoimmune disease, anemia and some kinds of latent infections. Does that mean low WBC is bad for CRers? Not necessarily, at least not for the usual reasons.


But the truth is that CR studies do show that calorie restriction makes it harder to recover, and death more likely, once an infection has gotten a foothold, as a result of CR's immunosuppressive effects, as discussed here. So that is a concern CR folks should take seriously, since we don't live in a germ-free lab like CR mice do.


As I mentioned yesterday, my next (major) post in this thread will be how (biochemically) CR & CE may work synergistically to fill in each others shortcomings, with the immunosuppressive effects of CR being a prime example.



There will never be peace in the world while there are animals in our bellies.

#160 Saul

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Posted 03 April 2016 - 05:11 PM

Hi Dean!


I found your proposed explanation of the disappointing findings of the NIA monkey study interesting:


A final, sad example of a study where CR & CE were decoupled with unfortunate results was the CR monkey study. As discussed here, the NIA monkeys (who, unlike the UW monkeys, were a real test of whether CR works or not relative to a healthy, obesity-avoiding diet) were housed at an average daily temperature that was above thermoneutrality. And we all know the disappointing upshot, the NIA monkeys did not live longer than controls, despite eating significantly fewer calories, and being thinner throughout their lives. Once again we see that CR without CE doesn't work.


  -- Saul

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