Ron Put

Dean, I do get it. I get that you are see nothing but BAT and that your confirmation biases make you ignore anything that contradicts them. But trust me, if I really felt that there was good evidence, I'd don the cold vest too (I don't get cold easily).

But with all due respect, you have provided only rather weak arguments in defense of your position.

Again, you are perfectly happy to accept and advance population studies in other areas, including CR, exercise and plant-based diets, but twist yourself into a pretzel trying to come up with an explanation why no population study supports your "cold exposure" conviction.

And it's not just my "common sense," it a host of studies which correlate increased deaths from cardiovascular events due to cold exposure in regular folks, including studies done in the UK where supposedly people don't get cold exposure when it's cold outside (I posted one earlier here).

Here is another study, in youngish, healthy men, which also supports and provides a possible explanation why people die more often in the cold:

Acute Effects of Exposure to Cold on Blood Pressure, Platelet Function and Sympathetic Nervous Activity in Humans
To clarify the mechanism for cold-related thrombosis, we evaluated responses of blood pressure, platelet function, and sympathetic nervous activity after cold exposure in ten healthy male volunteers (33 ± 2 years old). Mean blood pressure, β-thromboglobulin, platelet factor 4, and plasma noradrenaline were increased after cold exposure associated with significant falls in skin, oral, and urine temperature. The increase in plasma noradrenaline significantly correlated with the change in platelet aggregation (3 μΜ ADP: r = 0.73, P < .02, 3.0 μg/mL epinephrine: r = 0.65, P < .05), and with mean blood pressure in the warn environment (r = 0.76, P < .02). These results suggest that the cold-related increase in sympathetic nervous activity may contribute to enhancement of platelet function. This provides a possible explanation for the risk of thrombosis in cold weather in essential hypertension.
https://academic.oup.com/ajh/article-abstract/2/9/724/201779

Here is another one, which also helps explain why more people die in cold weather:
 

Cold Weather Hikes Blood Pressure, UF Scientist Warns

How much will your blood pressure increase in cold? The answer depends on variables such as the current temperature and wind chill, the temperatures you’re accustomed to, how long you’re exposed and your health, dress and activity level, Sun said. But it doesn’t take much; a previous study by Sun and his colleagues showed just five minutes’ exposure to a temperature of 52 degrees Fahrenheit can cause pressure to rise substantially. And a common medical evaluation known as the cold pressor test shows that a person who plunges one hand into freezing water for one minute will experience a rise in blood pressure lasting up to two hours.

People — and their furry mammalian counterparts — living in warmer climates aren’t immune to cold-induced blood-pressure change, either, he said. UF researchers found that a control group of 12 healthy mice kept at a constant 41 degrees Fahrenheit around the clock experienced a 50 percent increase in blood pressure after five weeks, he said.
...

Wearing a hat, scarf and gloves will minimize the amount of skin exposed, important because blood pressure increases don’t require full-body exposure, he said.

People whose jobs require prolonged or repeated exposure to cold, such as farmers, construction workers, meat cutters and law enforcement officers, should be particularly mindful of precautions, he said.
https://www.sciencedaily.com/releases/2005/02/050205124018.htm

But hey, what do I know...?

4 hours ago, Sibiriak said:

 

1) "Cold weather" is NOT the same as cold exposure (CE).    Your argument depends on falsely conflating the two.

1. Common sense tells us that "cold weather" strongly correlates with "cold exposure." I will repeat, until the last few decades, central heating was not commonplace even in developed countries. Most rooms and especially bedrooms in colder climates were not heated 24/7 and homes were not nearly as well insulated. Average room temperatures were likely to be lower than in modern climate controlled homes. Thus cold exposure would have been much more significant.

Similarly, many people work outdoors during the winter months in cold areas. They are exposed to temperatures close to, or below what the ice vests above provide, for probably longer periods, often over decades. As I mentioned earlier, if long-term cold exposure was correlated with longevity we would see a patter, as we see if most everything else. But we don't.

Based on the CE arguments, construction workers in Siberia should live longer than their counterparts in warmer areas of Russia. The opposite is true.

Someone living in the Dominican Republic can go around naked year around and still will not get the cold exposure of a construction worker in Siberia. Yet that Dominican is much likely to outlive the Russian by a decade or more, even with the marginally worse healthcare access and healthcare level in the DR.

2. There are a number of studies (I don't need to repost, as per your cartoon above) which clearly indicate significantly higher mortality (predominantly due to cardiovascular events) during and shortly after cold periods, even after adjusting for infectious diseases and other causes. The cold is not your friend, particularly if you are older.

I also ran across an interesting overview of another Blue Zone, Ikaria:

"In other studies, the metabolic syndrome (MetS) has been found to increase in prevalence among elderly individuals and seems associated with pathophysiological conditions that involve increased inflammation and oxidation process and mitochondrial and endothelium dysfunction. In previous studies testosterone levels have been found to be linked with cardiovascular health, as low testosterone levels seem to accompany aging-related diseases, like vascular dysfunction and atherosclerotic disease. In the IKARIA Study, the prevalence of MetS was associated with serum testosterone levels, only in men; at the same time, such relationship was not observed in women. Furthermore, serum testosterone levels were inversely associated with components of the MetS in both genders. When categories of lipids, hs-CRP, BMI, and insulin resistance levels were taken into account, testosterone lost its significance in predicting MetS, suggesting a mediating effect of these markers on the relationship between testosterone and the syndrome."
https://link.springer.com/referenceworkentry/10.1007/978-981-287-080-3_142-1

5 hours ago, Matt said:

Okinawan's start off almost half the level of DHEA and Testosterone (if I remember correctly) than Americans but it declines much more slowly. Eventually, Okinawan's end up with higher testosterone levels at older ages....

I haven't seen a mention of this anywhere, so if you could post a source, it'd be appreciated.

The Korean eunuch stuff is a very small sample, and frankly, not worth much, except as clickbait for the popular press. As it was pointed out at the time, it didn't take into account lifestyle or diet, and it was contradicted by most other evidence. I also posted earlier a fairly convincing study which strongly supports the theory that largely testosterone-driven risky behavior, rather than physiological reasons, account for much of the difference in lifespan between men and women (and the rest is likely mostly accounted for by the double X chromosome in women). 

Here is a good review of the consequences of castration in the major centers where the practice was found:
Long-Term Consequences of Castration in Men: Lessons from the Skoptzy and the Eunuchs of the Chinese and Ottoman Courts
"Indeed, there are no valid data indicating that castration has any effect on life span of men."
https://academic.oup.com/jcem/article/84/12/4324/2864451

Here is a mention of a very small study of castrati, which also didn't find much of a correlation with life span (mostly here as a rather interesting read):
"The effect of castration on lifespan has been debated. In a small study I did on 25 documented castrato singers born between 1610 and 1762 the mean lifespan was 65·1 years (SD 12·1) and was similar to that of 25 intact male singers born between 1605 and 1764 who lived a mean of 64·9 years (13·1) (unpublished). The relative longevity for this period may be explained by the fact that both groups lived fairly cosseted lives.is contradicted by Italian castrati studies."
https://www.usrf.org/news/010308-jenkins_lancet.html

There is also evidence that castration used to treat prostate cancer increases the likelihood of cardiovascular ischemic events.

Anyway, this is simply an attempt to counter likely erroneous assumptions about normal levels of testosterone being detrimental to longevity (and 412 ng/dL, while on the low side for 35, is within the normal range).

On 7/15/2019 at 7:02 AM, mccoy said:

By the way, this is obvious but we should always remind that protein ratio is a relative number. It is very arguable that it is a more important parameter rather than absolute protein quantity....

True. Although as CR appears to be related to energy expenditure deficits, relative protein ratio numbers are still of some value.

As to the map above, it appears to correlate more with the level and accessibility of healthcare, than with temperatures. Which is precisely my point: there is no population study I am aware of, which makes a claim that cold weather is beneficial to lifespan in humans (and if CE was beneficial, I would expect to see such a pattern, as we see it in other areas such as diet, lifestyle and physical activity). In fact, most population studies show that cold weather results in higher mortality (for various reasons, but it is important to remember that cold exposure significantly reduces arterial blood flow).

Thus, while I am aware of the lab results, I am not convinced that long-term CE exposure has longevity benefits. I don't want to beat a dead horse, but until I see some better long-term evidence in support of CE, I am chalking up the stellar numbers of Dean and Gordo to their CR practice, extremely healthy lifestyle and low protein, plant-based diets. And their genes must help a bit, of course.

7 hours ago, Sibiriak said:

Thanks!

So it was a comparison with U.S. men, not mainland Japanese men....

 

Actually, I remembered reading it in the context of Japanese men and just did another quick search, which shows the following testosterone levels for the the average Japanese male:

Age 60-69: 12 mmol/L, which is 346 ng/dL

Age 70-79: 11.5 mmol/L, which is 332 ng/dL.

https://onlinelibrary.wiley.com/doi/full/10.1111/j.1442-2042.2005.01143.x

So, while the Japanese as a group appear to retain slightly higher testosterone levels than Americans as they age, the Okinawans, at 439 ng/dL at the age of 70, still retained significantly higher testosterone levels than the average Japanese male.

The Okinawans also consumed about 80% of the calories consumed by the average Japanese on the mainland (effectively practicing CR) and their diet was significantly more heavily plant-based, with lower ratios of protein and fat.

1 hour ago, Sibiriak said:

I'm curious how big the difference was.   When you have a moment,  could you cite the study that has those testosterone numbers.

Reasonably big (pun intended :)

https://web.archive.org/web/20060206224552/http://www.okicent.org/study.html

3 hours ago, Saul said:

Metabolic Syndrome is about the opposite of the state of possibly all CRONnies; I'd guess that the only way CRON and MetS could arise together would be from a genetic defect.

  --  Saul

Actually, it appears well established that very low testosterone correlates with higher mortality. It is also associated with the accumulation of adipose tissue.

The study Dean cited doesn't have a baseline, compares a small number of CR subjects with subjects with unknown dietary and lifestyle habits, and as far as testosterone levels, contradicts the observation that elderly Okinawans, who effectively practiced moderate CR, combined with very low protein, very low fat predominantly plant-based diet, had higher levels of testosterone than their counterparts on the mainland, who consumed about 20% more calories.

The rhesus study I posted above is certainly better controlled and its results are in line with other research I've seen.

Again, my first reaction would be to argue that the very healthy lifestyle and diet of the CR subjects may negate immediate adverse manifestations of low testosterone (and come to think of it, what is "low" in this case?)

See this:
"On the other hand, circulating levels of sex hormones control fat mass distribution and expansion, mainly through activation of estrogen and androgen receptors in adipose tissue. Of interest, a recent work highlighted the profound impact of testosterone on cardiovascular function improving functional capacity, heart rate, muscle strength, and glucose metabolism in elderly patients with coronary heart failure [85]. We hypothesize that the cardiovascular effects of testosterone may be also mediated by adipose tissue, which embeds the heart and the most important vessels (coronaries, carotids, aorta, etc.) and is an active site of conversion of androgens into estrogens, through aromatase activity.

In conclusion, adequate levels and balance of circulating sex hormones are necessary to maintain a correct distribution and size of adipose tissue, which in turn is fundamental to keep a normal reproductive and sexual function. For this reason, screening of obese patients for hypogonadism is deemed necessary in order to better understand the pathophysiology of coexistent metabolic alteration, in order to target it with a replacement therapy. The delicate issue of whether testosterone decline, observed with aging, causes adipose tissue accumulation, or whether weight gain primarily disrupts testicular steroidogenesis, is still unclear and needs further studies."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3253446/

There is no strong evidence that low testosterone levels correlate with good health or longevity. On the contrary, very low testosterone levels correlate with all sorts of issues, including CVD and osteoporosis.

2 hours ago, Kenton said:

less than a half of one percent fat.  o_O

True, But every little bit helps :)

I just discovered it and quite like it.

7 hours ago, Dean Pomerleau said:

Of course the CR monkeys you are referring to (at the NIA) weren't really 30% CRed, and didn't live longer than controls (see here for discussion), so the fact that they didn't have lower T than controls doesn't really answer the question of whether serious CR lowers testosterone in humans (which it appears to in general, see [1]), or whether it is healthy or even necessary for longevity benefits of CR....

I do not make the claim that there is a clear answer. I am merely stating that the studies I've seen on testosterone levels are all over the map. There is clear evidence that testosterone declines as humans age, markedly so after 70 or so. There is clear evidence that very low levels of testosterone correlate with higher mortality, as do abnormally high levels. Notably, testosterone levels in Okinawan elderly men, who as a population effectively practiced CR, were higher than those measured among mainland Japanese subjects.

I looked at the study you posted and it is far from clear the low testosterone levels found among the 24 CR subjects are by themselves beneficial to longevity. It's entirely possible that their otherwise extremely healthy diet and lifestyle have a protective effect, despite the low levels of testosterone. We also don't have a T baseline for the CR subjects, making any conclusions based on this study questionable. The primate studies are at least considerably better controlled.

On 7/13/2019 at 1:33 AM, Matt said:

... But perhaps if you have a very high risk of cardiovascular disease and autoimmune disease like Lupus, then maybe DHA might save you from early death and it's a 'net benefit' for you.

 

I am aware of the castrati/Korean eunuchs studies, as well as of the many studies suggesting that testosterone supplementation is beneficial to longevity.

It seems to me that the results are all over the map and it's not as simple as that. I read recently a meta study which basically concluded that testosterone is to an extent responsible for the difference in average longevity  between men and women, but solely because it increases the propensity for risky behaviors in males (which includes lifestyle and diet habits).

The only relevant study on CR and testosterone levels (in rhesus monkeys) appears to suggest an actual increase in circulating testosterone after long-term 30% CR:

"

17 hours ago, Kenton said:

I wouldn't be too concerned about the ratio for Black Gram since it's almost fat free.

Here is the nutritional data I have found for Black Gram (also known as mungo beans or Urad Dal):

"Mungo beans — aka Urad Dal — are by far the best choice with 603mg Omega 3 and just 43mg Omega 6 in one cup cooked (not to be confused with mung beans)."

https://plenteousveg.com/vegan-sources-omega-3/

I'd view Musk and anything Musk says with skepticism (his narcissism, penchant for self-aggrandizing and shooting from the hip rival that of our (US) "Dear Leader").

But I would also give him credit for at times brilliant salesmanship and I would also put some faith in the extremely smart people this kind of money can hire.

Funny enough, Neuralink was founded in 2017 -- just enough time for Musk to have had the time to read Yuval Noah Harari's "Home Deus," the follow up to his widely successful "Sapiens." :)))

20 hours ago, Gordo said:

10%

Wow! How do you manage that?

(I saw that sundae photo you posted elsewhere.) :D

13 minutes ago, mikeccolella said:

Dean what would you say about the natives who lived in cold climates preindustrial? They lived in igloos. Surely they were exposed to pretty stressful levels of cold. AFAIK they were not in any way outliers for health or longevity.

I am with you on this one. Also, we need to consider that until fairly recently, central heating was not the norm, even in industrialized countries. Especially in rural areas, bedrooms were often without heat and farm houses in Sweden would have had room temperatures considered uncomfortably cold by today's standards.

I come from a pretty cold region and I remember people spending hours per day out in the cold. Even warm clothing would have provided temperatures closer to an ice vest than being naked in the tropics. If cold exposure had such significant impact on longevity, construction workers in Siberia would be the longest living folks in Russia. Yet the Siberians have a life expectancy about a full decade shorter than the already short life expectancy of the average Russian.

Here is another one of quite a few studies which show that cold temperatures contribute to excess deaths:  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4890842/

I certainly cannot argue with Dean's stellar biomarker numbers, but I would argue that they are the result of primarily long-term CR and low protein diet, exercise and extremely healthy eating and lifestyle habits. And genes, of course :)

Interesting study and it jives with others associating low (plant) protein diets with longevity.

But 6% is really low. The old traditional Okinawan diet is pegged at about 9% protein.

I was hovering about 13% average, hitting 14% on occasion, depending on the mix of legumes and nuts. But now that I've started eating more mushrooms, I am up to 15%.

What are you cold guys averaging for protein?

And poor rats, 4°C is cold, especially for a rat.

Thanks, Sibiriak. Yep, natto is MK-7, that's why I mentioned bioidentical MK-4 (which is synthetic in most supplements).

As to testosterone, no, I would not recommend getting shots if one is within the normal range. Particularly if one has prostate tumors.

But there is also a correlation of very low testosterone and mortality (there is a similar, but less pronounced correlation with very high testosterone):
 

Results: During an average 11.8-yr follow-up, 538 deaths occurred. Men whose total testosterone levels were in the lowest quartile (<241 ng/dl) were 40% [hazards ratio (HR) 1.40; 95% confidence interval (CI) 1.14–1.71] more likely to die than those with higher levels, independent of age, adiposity, and lifestyle. Additional adjustment for health status markers, lipids, lipoproteins, blood pressure, glycemia, adipocytokines, and estradiol levels had minimal effect on results. The low testosterone-mortality association was also independent of the metabolic syndrome, diabetes, and prevalent cardiovascular disease but was attenuated by adjustment for IL-6 and C-reactive protein. In cause-specific analyses, low testosterone predicted increased risk of cardiovascular (HR 1.38; 95% CI 1.02–1.85) and respiratory disease (HR 2.29; 95% CI 1.25–4.20) mortality but was not significantly related to cancer death (HR 1.34; 95% CI 0.89–2.00). Results were similar for bioavailable testosterone.

Conclusions: Testosterone insufficiency in older men is associated with increased risk of death over the following 20 yr, independent of multiple risk factors and several preexisting health conditions.

https://academic.oup.com/jcem/article/93/1/68/2598158

I just ran across a study which appears to indicate that vitamin K (MK-4, to be precise) boost testosterone by 50%. At least in rodents.

Summary: https://suppversity.blogspot.com/2011/10/1g-of-vitamin-k2-mk-4-could-boost-your.html
Study: https://lipidworld.biomedcentral.com/articles/10.1186/1476-511X-10-158

Eat your natto (which has tons of MK-7) and if you want extra testerone, perhaps supplement with a bioidentical MK-4 supplement (synthetic, so OK for vegans).

22 hours ago, Dean Pomerleau said:

Tom, 

Here is a post where I discuss protocols shown to be effective at boosting BAT in carefully controlled trials. A couple hours a day in shorts and a t-shirt at 62F should be effective. 

Since it isn't practical to get ambient temperature that low in summer, lately I've been wearing my cold vest for ~3h / day while walking slowly at my treadmill desk and another ~3h sitting around reading etc. For both I've got a strong fan blowing on me too. 

This is in addition to a couple minute cold shower and sleeping in a room at 70F with no shirt or sheet and with a fan blowing on me. 

Dean 

Dude, you are hardcore! And your numbers are generally amazing.

I agree with you that exercise is highly beneficial and that calorie deficit is the important factor for CR (I posted a study confirming in a couple of other threads, but this is also supported by population studies: the folks in most the Blue Zones I am aware of, engage in higher than average physical activity).

I also think it's likely that given your diet, CR and exercise, the added cold exposure may have a minimal beneficial effect. But, whatever it is, I can't argue with your numbers.

But I am still curious as to the isolated longer-term effect of just cold exposure. So, if someone here, like Tom above, is about to embark on CE, it'd be great to do a blood test before they do, and compare the results to another blood test six month or a year later.

Ah, it was mccoy who just had a physical, not Dean.

But maybe Dean should run a blood panel before embarking on the cold vest journey and tell us what changed in six months?

Or maybe Dean can convince mccoy to get one of these vests :D

In the last month or so I've started using Cronometer (before I used Myfitnesspall for a year) and with the new data available to me in Cronometer, I decided to drive my Omega-3 to Omega-6 ratio closer to 1:1 and see what happens in 6 months.

My main source of Omega-3 is unfortified brown flax meal of which I eat between 40 and 70 grams a day. I eat smaller amounts of chia seeds and steel cut oats (all organic, so not fortified). I also eat about 15-20 grams of walnuts and about 20 grams of "raw" cacao nibs every day. I've started eating mushrooms every day as well, in addition to legumes (Black Gram, since it has a great Omega-3 to Omega-6 ratio, lentils, quinoa, chick peas, occasionally black rice, etc.). I also eat a good amount of leafy greens, roots, broccoli sprouts and an apple or a pear almost every day.
My last test showed (I am in my late 50s):

Cholesterol: 170
LDL: 87
HDL: 73
Triglycerides: 54
HSCRP: 0.35 (this was a weird jump from 0.02 a year earlier, but the change doesn't appear significant).

My resting heart rate is 50-51 on Fitbit and 48 according to Cardiogram.

I've stopped taking multi-vitamins, now I take:
B12 (2000)
D (2000) (I am genetically predisposed to have somewhat lower absorption of both and my numbers show me at the lower end)
gGlucosamine (1000)
Q10 (200)
Citracal (half a dose (1 caplet), mostly because I found a large bottle :)
Alpha-GPC (300)
Curcumin (Natrol 2x250 CurcuWin)

I also take 2 caps of Olive Leaf extract, but when I run out, I am switching to bulk Olive Leaf Powder from Frontier, maybe 3-4 grams a day.

I am a vegetarian, mostly vegan, except that I eat cheese maybe three times a month and eggs maybe once a month.

Since I started being more religious about tracking my food intake and nutrients with Cronometer, as well as going for a three mile hilly hike/run 5-6 days a week, my BMI has dropped to the high 18 and my body fat, according to my scale hovers about 10%. I now eat within a 9-12 hour window. I am almost struggling to eat enough to keep up to 80%-85% of my caloric requirement, based on Fitbit and Cronometer -- I have to often eat over 2000 calories to do it. Don't need to get skinnier :) I am 6'1", 141 lbs today, 13.8 lbs fat, 120.6 lbs muscle mass, 6.5 lbs bone mass and 85.7 lbs body water.

I'll post what happens based on the Omega-3 to Omega-6 ratio change in about six months, when I'll have another blood panel. I like data and this is kind of fun for me.

I am curious if someone else has already done it?

I'd be curious if someone here, who is just starting, or resuming the practice of regular cold exposure, is running tests before beginning CE, to see what effects regular CE might have in their particular case in say, six months? I'd be interesting, even as anecdotal evidence (presuming other variables such as diet, caloric intake and exercise remain roughly the same).

It'd be particularly informative to see if there are notable changes in blood glucose, lipids, HSCRP and triglycerides. And anything else of note.

I kind of did this when I cut my olive oil intake and saw a difference.

It'd be interesting.

Edit, @Dean Pomerleau

Since Dean is just restarting CE (if my understanding is correct) and since he also just had a physical, including a blood panel, it may be a good personal experiment.
 

12 hours ago, Dean Pomerleau said:

Sigh... Except that I've shown you here that living in a colder climate does correlated positively with longer lifespan in a study of nearly 100 different species whose habitats range over many different latitudes.

And I've explained to you repeatedly why you shouldn't expect to see it in humans for a variety of reasons (see here).

Actually, what you've posted is hardly compelling evidence for anything. Repeating it doesn't change that.

I have posted studies showing that cold weather results in spikes in mortality -- the fact is that more people die during the winter months than during the summer. Virtually all Blue Zones are in temperate or warm climate and Southern Europe enjoys greater longevity than Northern Europe, despite significant disparities in income and access to advanced healthcare in the North's favor.

Again, you seem content to accept population studies to support your beliefs in other areas, but ignore them or attack them here.

12 hours ago, Dean Pomerleau said:

OMG. I can't believe you actually said that. First of all, your wrong and you clearly didn't even bother to check. ...

There are no marked longevity differences between native populations at warm or cold latitudes and there is no study I have seen which claims that there are. Again, if anything, warm and temperate climate zones appear to be more conducive to longevity when looking at entire populations.

I used "Bushmen" and "Inuits" to illustrate a point. But your response, citing Inuit life expectancy (not necessarily related to longevity) is facetious, or at best, irrelevant: Canada provides considerably better healthcare access and financial support nowadays than found in Angola. Here is a much more accurate estimate of Inuit life expectancy, in 1965:
"[L]ife expectancy of the Eskimo is about 32 years. …" 
http://perfecthealthdiet.com/2011/07/serum-cholesterol-among-the-eskimos-and-inuit/

And here is something comparing the Inuit to the Masai in terms of diet, but from which it would appear that the Masai are in fact healthier overall: https://nutritionstudies.org/masai-and-inuit-high-protein-diets-a-closer-look/

12 hours ago, Dean Pomerleau said:

You've alluded to "short term" benefits of CE before. I challenged you there and I challenge you again to provide actual evidence to back of the idea of diminishing benefits of CE over time (e.g. on glucose metabolic). So far you have just expressing your (misguided) opinion, as far as I can tell.

Perhaps if you can look beyond BAT in short term experiments, you can see why things are not quite as simple as freezing oneself and finding longevity.

First, again, if your theory was right over long periods of time, population studies would show a longevity trend expressed at higher latitudes (for some other species, there is such evidence). But population studies do not show such evidence and in fact the opposite is more likely.

Second, while BAT increases may be beneficial, longer term cold exposure has its drawbacks and it may be accompanied by WAT increases which provide insulation effect. This is also noted in the study I posted above, together with the finding that cold air and cold water exposure may produce opposite metabolic effects.

See also this, which supports the study I posted above:

"Due to its high energy consuming characteristics, brown adipose tissue (BAT) has been suggested as a key player in energy metabolism. Cold exposure is a physiological activator of BAT. Intermittent cold exposure (ICE), unlike persistent exposure, is clinically feasible. The main objective of this study was to investigate whether ICE reduces adiposity in C57BL/6 mice. Surprisingly, we found that ICE actually increased adiposity despite enhancing Ucp1 expression in BAT and inducing beige adipocytes in subcutaneous white adipose tissue. ICE did not alter basal systemic insulin sensitivity, but it increased liver triglyceride content and secretion rate as well as blood triglyceride levels. Gene profiling further demonstrated that ICE, despite suppressing lipogenic gene expression in white adipose tissue and liver during cold exposure, enhanced lipogenesis between the exposure periods. Together, our results indicate that despite enhancing BAT recruitment, ICE in mice increases fat accumulation by stimulating de novo lipogenesis.

... our dietary intervention study showed that food restriction did not prevent ICE from causing expansion of adiposity, arguing against hyperphagia as the major cause of ICE-induced fat accumulation. ... Besides mild hyperphagia and de novo adipogenesis of beige cells and white adipocytes in subcutaneous fat, we also found a reduction of lean mass during cold exposure that recovered less robustly than fat mass during non-exposure periods (data not shown). Therefore, we hypothesize that ICE shifts the metabolism in favor of lipogenesis at the expense of muscle anabolism during non-exposure periods, which contributes to the fat accumulation. Although our study did not see any difference in energy expenditure, ICE treatment increased RER during light cycle and diminished the RER oscillation (Fig. 2J&K). This result indicates that ICE alters fuel source of metabolism and further supports the in favoring lipogenesis notion."
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4008632/

Third, cold exposure raises blood pressure and cholesterol serum, as well as triglycerides, which for many is a recipe for disaster. A quick search finds stuff like this:

"[The] distribution of ischaemic heart disease (IHD) could be partly explained by variations in degrees of cold exposure, which includes wind and rain as well as temperature, with frequent exposure to cold being more harmful than steady exposure. Blood pressure (BP) and serum cholesterol are raised in response to acute and chronic exposure to cold. ... There are many acute responses to cold which could trigger a myocardial infarction (MI) and therefore cold is probably a major precipitating factor in many cases of MI." https://www.sciencedirect.com/science/article/abs/pii/S0033350605801106

I am out of time, but I hope this helps clarify why I don't find compelling your argument that prolonged cold exposure promotes longevity. If you want BAT, there are likely better ways to increase it than freezing. It may be healthier to just eat mushrooms, as Gordo noted above.

At the very least, since it's a well-established fact that cold exposure narrows the arteries, nobody with high blood pressure should be jumping under cold showers.

Cheers.

Thanks to Dean for the informative posts. Here is another interesting overview on the subject, including an evolutionary perspective:

"Reviews on whole body human cold adaptation generally do not distinguish between population studies and dedicated acclimation studies, leading to confusing results. Population studies show that indigenous black Africans have reduced shivering thermogenesis in the cold and poor cold induced vasodilation in fingers and toes compared to Caucasians and Inuit. About 40,000 y after humans left Africa, natives in cold terrestrial areas seems to have developed not only behavioral adaptations, but also physiological adaptations to cold. Dedicated studies show that repeated whole body exposure of individual volunteers, mainly Caucasians, to severe cold results in reduced cold sensation but no major physiological changes. Repeated cold water immersion seems to slightly reduce metabolic heat production, while repeated exposure to milder cold conditions shows some increase in metabolic heat production, in particular non-shivering thermogenesis. In conclusion, human cold adaptation in the form of increased metabolism and insulation seems to have occurred during recent evolution in populations, but cannot be developed during a lifetime in cold conditions as encountered in temperate and arctic regions. Therefore, we mainly depend on our behavioral skills to live in and survive the cold."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4861193/

See also :https://royalsocietypublishing.org/doi/full/10.1098/rspb.2009.0752

Still, nothing I see strikes me as compelling evidence that cold exposure over the long term correlates with longevity. It appears that while cold exposure has some beneficial short term effects, there are also negative effects and overall, there is no evidence that it positively impacts longevity. Mind you, heat exposure has beneficial short term effects, based on studies I've seen.

But the bottom line is, we see population-wide evidence that humans who exercise, who eat low protein and plant-based diet, who don't smoke or drink excessively and who practice CR (traditionally, largely because of limited access to calories), generally live longer than populations which do not. But the longevity of Inuits is about the same as the longevity of Bushmen, despite the dramatically different temperatures of their native environments.

While BMR is not necessarily correlated with longevity in all species, in humans it appears to be. Native populations living in cold climates appear to have higher BMR on average.

See this, for example (it's sort of on point):

"Despite longstanding controversies from animal studies on the relationship between basal metabolic rate (BMR) and longevity, whether BMR is a risk factor for mortality has never been tested in humans. We evaluate the longitudinal changes in BMR and the relationship between BMR and mortality in the Baltimore Longitudinal Study of Aging (BLSA) participants.

Methods

BMR and medical information were collected at the study entry and approximately every 2 years in 1227 participants (972 men) over a 40-year follow-up. BMR, expressed as kcal/m2/h, was estimated from the basal O2 consumption and CO2 production measured by open-circuit method. Data on all-cause and specific-cause mortality were also obtained.

Result

BMR declined with age at a rate that accelerated at older ages. Independent of age, participants who died had a higher BMR compared to those who survived. BMR was a significant risk factor for mortality independent of secular trends in mortality and other well-recognized risk factors for mortality, such as age, body mass index, smoking, white blood cell count, and diabetes. BMR was nonlinearly associated with mortality. The lowest mortality rate was found in the BMR range 31.3–33.9 kcal/m2/h. Participants with BMR in the range 33.9–36.4 kcal/m2/h and above the threshold of 36.4 kcal/m2/h experienced 28% (hazard ratio: 1.28; 95% confidence interval, 1.02–1.61) and 53% (hazard ratio: 1.53; 95% confidence interval, 1.19–1.96) higher mortality risk compared to participants with BMR 31.3–33.9 kcal/m2/h.

Conclusion

We confirm previous findings of an age-related decline of BMR. In our study, a blunted age-related decline in BMR was associated with higher mortality, suggesting that such condition reflects poor health status."

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4984846/

Perhaps a silly question, but why would anyone on a CR forum choose to bulk up on a full daily dose of methionine at one fell swoop?

There is quite a bit of evidence that restricting methionine and some other BCAAs may be an integral part of the process taking place during CR (which seems to be largely due to reduced protein intake). See for example https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5008916/