Backpacker Fact-Checker, #2: Heat Loss Through the Head
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- čas přidán 13. 09. 2024
- This video series will take a skeptical look at some of the Trail Tales told frequently about backpacking, often without evidence or references.
In each episode, I’ll do my best to try and track down the source of each claim so that you can make your own, informed decisions about the truth and/or usefulness of the supposed information.
Episode #2 examines the familiar rule that “40 to 45% of your heat is lost through your head”.
View the Backpack Fact-Checker Series here:
• Backpacker Fact-Checker
Why yes, I will drop what I'm doing to watch the new GearSkeptic video!
Same here! 👍
Seriously! I have a lab assignment due on sunday that's supposed to be a 3 week lab, I just started it 2 hours ago and stopped to watch this XD.
✅
Same!!!!
Why yes, that's what I'm doing instead of studying for my exams.
Another good backpack fact-checker to do would be the quite common contention that sleeping naked in a sleeping bag is warmer than wearing insulated clothing layers within the same sleeping bag
This got already debunked. It is only warmer to sleep naked if your clothes are soaking wet. But dry clothes add to your insulation and help keeping a warmer body temperature.
How the hell does that work?
@@dianauwu1312 It doesn't - it's a myth, but is quite a commonly held belief, so it'd be great to show the science to prove it incorrect once and for all. Wearing extra insulated clothes inside a bag is warmer as you'd expect (except in some very niche circumstances such as soaked clothing or extremely tight restriction by the bag).
I think this comes from the fact that the inside of your sleeping bag feels colder when you're wearing cloths. It feels less "cozy". But that very fact let's you know that your clothes are keeping more of your heat against your body, creating a smaller temperature differential between the inside and outside of your bag, thus lowering heat flow from inside your bag to outside (meaning you're loosing less heat to the outside, even if / because the inside of your bag feels colder).
I’ve had tenured scouters and veterans swear by this. I’ve heard something like if you have other layers then the bag can’t properly reflect the heat back at you. Too many layers means not enough heat gets to bag and reflects back so you never get warm. Doesn’t make sense to me.
Also I think most people muddy the water with: 1. Wearing layers to bed you’ve already been perspiring in 2. Wearing layers like cotton, getting too warm and sweaty, then cold and miserable and 3. Sharing a bag with another person and less clothing means more shared warmth.
We bout to learn tonight fellas!
Thank you for your hard work and your dedication. It is greatly appreciated. The amount of houra that goes into these videos is not lost on me. Thank you for your valuable time. Please continue creating such incredible content. The information you provide is truly significant.
Thank you! I appreciate that very much.
With no sass I would comment places that lose heat...have hair. Nature retained a few key locations.
Stylish headwear is always a priority! Brilliant! Well done.
You, sir, are nailing it!
The Carl Sagan of backpacking that we didn't know we needed.
I’M NOT WORTHY! but, thx very much!
@@GearSkeptic Modesty 😌 .. definitely a Virtue 😏.
I feel more Paul Harrel vibes. 👍
I appreciate the amount of work you invest in your videos. I also greatly appreciate the level-headed and scientific approach you employ.
Another myth to investigate would be "Synthetic insulation keeps you warm when wet."
Thanks for your enlightening videos!
Good suggestion, and thanks much!
That’s definitely not a myth. 🤦🏻♂️
Synthetic insulation still retains most of its loft when wet.
@@AaronVets Depends what kind/type of synthetic insulation. More so in the case of continuous filiament insulation like Climashield Apex or other structured type insulation like foam, slightly less so in the case of larger, hollow fiber loose fill. And less so again, in the case of loose fill, solid microfiber synthetic insulation.
Still going through the video but my first impression of the field manual based on its wording is that if you are appropriately clothed the exposed head, wrist and ankles makes up 40% of your heat loss not that you straight up lose that heat from your head overall.
It is very odd wording, because it says that an exposed neck or wrist can be even more. That would put the neck or wrist over 50% leaving me wondering where the head then is. It's odd that it suggests exposed neck loses more heat than exposed head.
The point about major arteries being rapidly cooled more directly affecting your core temperature may be the sticking point there.
Case in point: the field response to a heat casualty is bedsheets kept in coolers full of ice water. You wrap the sheets around the junctional areas of the neck, armpit, and groin because all the major arteries in there will drop the casualty's core temperature quicker once cooled.
Also, Palmar cooling is an effective way to heat and cool the core through the palms, bottom of feet, and cheek area. but if too low of a temp is applied to these areas, vasoconstriction occurs which can essentially trap core temp. So, if you're trying to cool someone who's hyperthermic, putting a very cool towel on the head or neck is only best at cooling that specific area but does little to core temp due to vasoconstriction creating the inability to transfer that lower temp to the core.
A quick calculation reveals that the head loses 40-45% more heat than the rest of the body. That is to say, 7% of a surface area losing 10% of the total heat, means 10/7 = ~1.43 or 43% more heat per unit area by comparison with unit areas of the rest of the body. I wonder if this could be the source of the confusion.
That would be funny. Imagine the myth stemming from some editor that is bad at math, “cleaning up” some statement, so it is “easier to understand”.
Our heads are highly irrigated. I learned this personally, when mine became a blood sprinkler.
@@eanredur9920I'd buy that story.
Sounds like a very military thing to do
Dear Gearsceptic,
I follow your channel now quite a while and love the scientific approach on gear testing and analysis of methods and myths, etc.
I would love to see if you were able to do a deep dive into the aluminum cookware and its real health risk thematic in the next years 😊
I see a lot of fear mongering, misinformation, or ignorance out there in the outdoor area. Also among big channels.
Explicit in one channel I see the fear of particles going from an aluminum vessel into the drinking water, avoiding plastic bottles because of the same fear till changing the house water pipes (plastic), to stainless steel.
They recommend stainless steel, even the ones that are very cheap and don't even have composition stamps and sometimes don't have any certificates because they are mostly from China. I live in Taiwan and come across many "chinesium" products, and I know that the Chinese counterfeit even lables as well as safety and health risk certificates to save production costs in order to offer the lowest price amongst the competitors.
For me, I like the benefit of light weight and the cheap price from aluminum. I don't see a health risk if use aluminum cookware in outdoor activities and use them wisely. My aluminum cookware is used for boiling water only, no scraping or scratching...
The other aluminum pan has a non-stick coating (probably a "forever-chemical", which is also worth looking at because it is probably used on a daily basis in most households), wich I use once a month ore less and mild frying onions and some meat with a soft wooden spatula.
Hope to see if the "alternatives" are really the better choice or even worse, if designated plastic bottles / containers are a concern at all ( if being aware that they have an expiration date ), forever-chemicals in comparison.
Hope my novel was not that intimidating to read and excuse me for writing errors, but English is not my mother language.
Best greetings from Taiwan and keep up the good work ❤
That sounds like an interesting idea. I will add it to my list of topics to explore!
@gearskeptic6355 thanks for your time ❤️
The sonic boom you just heard was my mouse moving to the subscribe button.
:) Thanks!
Thanks again for all you do! You present these subjects very well.
As always well covered Gear Skeptic, you even mention points for a stylish hat. Wearing one might result in a emotionally warming sensation which coupled with the consumption of a chocolate bar could melt the ice off the tent you are sleeping in.
Ah, the Chocolate-Style Synergy. I have heard of this.
Thank you for your videos, I personally use the same sleeping bag in a variety of situations. When it's warm, I don't put on the hat and it makes a huge difference. Putting an arm out wouldn't have the same effect in my experience. I think the effect on core temperature is more significant than you might think. But I have only my personal experience sleeping outside to make that claim. I love what you do
Awesome work! Thanks for sharing, your work is very much appreciated!
Thanks much! I do appreciate it.
Damn, how did I miss this upload! Catching up now!
When it is very cold, I'm a fan of balaclavas plus hoods. Somewhat cold--just hoods.
As a young mother, I had heard the heat loss through head stats. When my kitties got dangerously high body temps, (like in the 104 range), I would properly dose them with age-appropriate anti-pyretic & run a lukewarm bath. In they went, on back, with head & neck supported. I would cup water over their head, with face staying dry for maybe 19 min or so. In my mommy mind, this pulled heat from their head into the water, as well as cooled blood vessels in neck. My hope was to artificially cool circulating blood temperature while waiting for whatever fever med to kick in. Not talking cold water… just slightly cooler than body temp. After drying off, I’d put a cold cloth on head & rotate around neck/ear area to pull heat. It was soothing for kiddos & supported quicker lowering of fever to mommy-comfortable level. It worked. Only a handful of kiddo fevers ever seemed out of hand, so didn’t use this method often. As an adult, I’ve used similar method to stay comfortable in high 90’s summer temps by using cooling cloth products around my neck & over head, (under a hat). Keeping circulating blood flow cool has prevented heat stroke & enabled me to walk and even be comfy in my home without A/C running. I didn’t turn A/C on once last summer. I think your presentation explains the mechanism behind the mommy approach. As an adult, when temps are in high 90’s, I keep very comfortable walking & yard-working with use of a high quality cooling cloth around neck. It cools blood flow & helps my body not to overheat. For extended periods, I dunk my head & put a cold, wet cloth under a hat as well. This has prevented heat-stroke, something I’m susceptible to. Supportive management of blood temperatures in
winter, summer and limited health conditions, has been helpful in my personal life experience. Thx for video!
Interesting, and you are most welcome!
A curious thought and a fact to check below!
I've heard it said: For every five degrees higher the temperature is, your performance may decrease by up to 2 percent
Combining the thinking between shoe weight, heat loss / retention, and hydration amounts... it seems to point towards a heavier but highly breathable shoe being favored for most hiking. In warm weather in particular, given that the foot temps in the shoe often exceed 110 F (and need more water to off set that burn rate). Obvious, but anecdotal experience says the same. It would be fascinating to get a detailed take / optimization guild here. How well does the many socks and hiking sandals approach hold up? It works great for bike-packing, but for some reason I rarely start a day hike that way, much less a longer one. Considering that the head accounts for roughly proportional heat loss, I suspect the shoes may have an added factor as they are moving faster though the air. Kind of odd that damp socks are the hiking issue they are. Evaporative cooling is by far the most efficient cooling method we have, strange that we end up boiling our feet so often. What say you GearSkeptic?
I've been enjoying the all thought and work put into these video. It feels like a more accessible and more accurate guide book, and it is just nice to see someone play the long game well.
A lot of different concepts there! Where it leads me is the strategy of different shoes for different hiking environments. Obviously, in snow you want more of a winter boot. But, there are trade-offs to consider for transitional situations like where you may encounter a variety of conditions.
A tricky one is where your feet get wet when it is cool, but not cold. At milder temps, you’re fine with thin shoes. But, wet feet in otherwise “cool” conditions can easily become cold. Sweat is an issue for becoming cold once you stop hiking. I feel that’s true of your shoes and socks, same as it is for you base layers of clothing. People will caution you to slow down, if needed, to avoid sweating…but then advocate walking through puddles with trail runners. 🤷🏻♂️
Hmmm...much to think on here. I do go with a "belt and suspenders" approach. Hat, neck gaiter and gloves. Whether or not I need it, it does allow me more options when working to vent excess heat built up during the hike. Thanks for sharing
Just here to say that I love your videos!
Thanks!
Always too great of info!!! 🔥
I think this might be a scenario where anecdotal evidence is simply more useful than the results of a study. It's an interesting topic though! In my (unwritten) pro-tip book, if you're cold, you'll definitely want cover your head and neck well before your hands. Maybe even before you cover your lower half 😅
Keep up the videos! Great stuff
Could you imagine if the blood vessels in our heads and necks vasoconstricted everytime we got cold? 🤣
Now that I revisit this video after shaving my head…
I find wearing sweaters/jackets/pants that are comfortable during exertion, but too cold when standing still is the easiest to thermoregulate in, because by adding a hat, scarf and/or gloves I can make myself much warmer far easier and with less weight than adding another sweater or something. I can keep those extra items easily in reach and put them on or take them off quickly, without stopping and without removing my pack or anything. If I go from the lee side of a mountain around to the windy side, or if I go from climbing to level ground, or if the cool morning starts to warm up or a warm day starts to cool down, etc - gloves, scarf and hat are by far the easiest way to dial in comfort. I think some of this is more psychological than actual reduction of heat loss, but I'll take it!
I have no idea who you are but a core memory of mine is about this topic. So I will drop whatever I'm doing and watch gear skeptic.
I had a survival instructor tell us “if your feet are cold but you hat on”.
Probably good idea, at least no percentages involved. 😊
Hair vs bald? Facial hair vs clean shaven? Alcohol vs sober?
A useful fact checker/useful information would be to examine sun exposure. Common perception is exposure is greatest at solar noon. However a near vertical sun hitting an upright human mostly hits the head and shoulders and these are easily covered. Prudent hikers cover themselves. As the sun lowers the intensity declines but direct sun now hits below the hat brim and on vertical legs. Thus peak exposure may be earlier and later in the day. Or perhaps indirect UV bouncing off the ground is more important? We need to clarify that peak UV exposure is probably not at solar noon.
Hmm…cover a mannequin with UV reactive test strips? Must ponder…
@@GearSkeptic A variety of low cost UV sensors are available (e.g., on Amazon) and probably some published papers are around with varying quality.
Can you also look into sun umbrellas? I can't find much study on the shiny metallic ones vs multi layer vs rain umbrella vs light colored vs dark colored. It's all hearsay from people who are selling or already bought one 🤷♀️
I haven’t seen much, either, but I will keep an eye out!
Appreciate all you've done gs.
Someone should study hand movements per this channel.
Great video! Super interesting as always.
I was wondering whether the fact that you can "heat" your arms and legs by walking, digging trenches/latrines, jumping jacks etc. would make a difference. You can't really exercise your head to produce more heat (although maybe really hard math problems might do it 😊). From what I understood the 2006 study was done with inactive test subjects, so no additional heat was produced from the major arm, leg and back muscle groups.
The military manual was presumably written for soldiers who would be required to be physically active (and ideally maintain high morale). The effect of activity would also explain the anecdotal evidence that a previous poster wrote about hiking in cold weather with shorts, t-shirt and a beanie. I have had similar experience myself while hiking in Iceland, where I only felt cold once we stopped for breaks (this is obviously equally anecdotal).
That said, the overall energy loss will be high with only light clothing on the body, but if food is plentiful then the energy loss can be compensated.
As a native of really cold region I kinda laughed on conclusion "so it's up to you whether to cover your head or not" because it clearly reveals someone from relatively mild climate. I used to wear both cap and a scarf (covering not only neck but up to my eyes, lol) with a hood on top of it all. And it was still cold sometimes. Going outside with naked head? Well, maybe, if I'm a bit suicidal today.
All I know is if I don't cover my head on a cold nite in my tent I can become quite cold so I use a trapper hat with a chin strap so it does not fall off in my restless sleep. If I think I need to I will even add a thin beanie under the trapper hat.
When I see a new vid from GearSkeptic, I'm clicking
My question would be how dangerous would loss of heat through the head be. Would it cause decreased cognition due to less blood flow or other metrics? Our brain is slightly important here.
Only restricting blood flow to the brain as little as possible is the reason that the head has an unproportionate effect on core temperature. And vice versa, if the head is cold, but the core warm, the core will warm up the head with higher “priority” than the limbs. So, unless you become hyperthermic, you should not experience reduced cognitive function.
An exception would be rapid exposure (e.g., being thrown into freezing cold water) where a panic reaction can be triggered. But here the cold would only be the trigger, not the cause.
So... what would you pick? Hypothermia or frostbite? Sounds equally awful to me.
Frostbite mostly isn't lethal.
I think when alone, hypothermia is worse, as your ability to stay alive goes down drastically. When with a group that will heat you up, it is easier to recover from. Therefore: Take frostbite if it is about pure survival, hypothermia if dying is not an acute danger.
Agreed. Not that it's a realistic scenario, but if you had one extra piece of clothing and you could only cover your hands or your head, I would protect the head and risk frostbite in the fingers. Better to lose a digit or two to frostbite than die of hypothermia.
11:50 I just watched that about 8 times in a row.
🥸
Far be it from me to assume things about someone else's claim, but it seems reasonable that the army expects soldiers to already be clothed when they throw out the 40-45 percent number.
I'm not a technical guy, but I do know the human body better than most. Just as the body protects the core by constricting vessels in the hands and feet, it doesn't do this to protect the brain, since we need that perhaps even more than the core. (Can't overcome hypothermia if we can't think). Anyone who has suffered, or seen someone else suffer a significant head wound, knows just how disproportionate the blood flow is to the brain. Experience is not anything that I can quantify, but I value it over clinical studies. That's why I place great value on buying outer layers with hoods and having a warm hat or balaclava to sleep in.
I appreciate the amazing work you have done on your channel. In fact I love it. Maybe another video on the warmth to weight rate ratio when buying a puffy; hooded vs. hoodless?
Thank you for your videos, How do you explain that men have lost most of their fur during evolution, except on the head if it's not a major Heat Loss factor?
Manuals are as much written to tell soldiers what to do as well as tell officers and senior NCOs what not to do.
In this case a CSM who doesn't like seeing soldiers wear knit caps or neck gaiters or gloves or what have you now can't just tell them to suck it up and be cold because the manual clearly states that protecting these areas of the body is important. And if he continues to defy that not only will the blame for cold casualties be laid at his feet he already had clear doctrinal guidance telling him to do otherwise.
Ugh, giving me flashbacks 😂😂😂. I'd been a backpacker for years before joining the Army, well versed in living outdoors and carrying a pack. But NOOOOOOO....The right way, the wrong way, and the Army way. Did my 4 years and got out!
Thank you for your observations. I have been hillwalking in the Scottish highlands for more than 50 years. Regardless of the results of your inquiry I have on many occasions witnessed folk that are not wearing a head covering (hood,torque/snood, balaclava, hat etc.,) suffering headaches, of differing severity, which impare map reading skills, social interaction with others, and befuddle decision making. This affects those that are follicly challenged (bald) the most. My advice, wear a hat when it gets cold, before you develop a headache.
You also didn't refer in your presentation the varying effect altitude might have on this subject. Headwear is also important in countering the effects of the windchill factor.
Having been accused of being a Quant myself, I can appreciate your argument. But consider that we primates have abandoned most of our hair except on the head and groin, regions of our core that don't store insulating fat.
You can also just wear hats to cover bad or missing hair!😉
And keep off the bird poop
If we handcuff him behind his back will his videos simply be a series of pics and slides? 🤣🤣🤣 Just messing with you, I like the series.
🤚🏼🖐🏼😱
Yeah, but I live in Florida
Definitely, hat and no pants for you.
Interesting 🤔
I live near arctic zone... It's not so simple in reality :D It depends a lot on is it windy, are you working and do you have hair. More important is the fingers and toes. Many people have lost them in freezing condition, but no one has ever lost their head ;)
Thru-hikers face two primary states, hiking and sleeping. Both are questions of temperature regulation, not so much loss.
Hiking: Regulating temperature can be accomplished by clothing any of the aforementioned body parts, however... Adding or subtracting core clothing requires stopping, taking off pack, often opening pack, etc.. Whereas, adding or subtracting gloves and headwear requires none of that.
Sleeping: it's not like it's a choice between one (head) or the other (body). Hikers are going to seek roughly equal warmth to each region.
Regarding the value of head insulation vs body, it's this author's experience that it's better to regulate hands first, then head, then feet and core last.
Other considerations apparently missed are that heat rises such that pants heat leaks away into midsection, then chest, but that chest leakage does little or nothing to warm head. This was missed in analysis. Lesson? Hoods are better than hats for heat retention.
Most hikers prefer shorts well into the below-freezing temperature-range, thus further disproving the percent-of-surface-area theory.
Lastly, while there is modest flexibility in trading-off one slightly warmer region for a colder one, these are secondary effects. Hike with coldest core possible and regulate with extremities. Hot core leads to sweating, which is death in cold conditions. 2) Nobody can stand a head that's too hot, regardless core temperature. Again, flexibility to trade-off an overly hot region against a cold region is very limited.
Head loss is connected with much more serious consequences than being cold... Just saying. 😜
Now, why did I just think of the old adage: Never apply tourniquet to head wound?
@@GearSkeptic all these questions... 🤪🤪
Doesn’t the second one being false make the first one true. At least sort of. Sure. The immediate heat loss measured on a short timescale is mainly a function of exposed area. But the second one being true says that blood flow to the head has ‘better association’ to the core temperature due to that lack of flow control capability. Which means that the head will be better able to sustain a higher rate of heat loss for the core. So heat loss from the head does have a disproportionate effect on core temperature. It just take a while to become more important.
Am I misunderstanding something.
Total heat loss through the head is nowhere near 40 to 45%. Nothing about the core temp can make the first claim true.
In terms of which exposed body part would get you in trouble fastest if sustained in dangerous temps long enough, the study doesn’t address that. At the end of the video, I did mention that going from a comfort scenario to a survival one I would give extra consideration to core temp, and chose frostbite over hypothermia if I had to.
@@GearSkeptic
If you are talking purely about immediate heat loss the claim is clearly false. But the second claim would imply that the head has a disproportionate effect on warmth as a whole. I guess wording can be important. But closely wordsmithing can lose the forest for the trees. So to speak.
Like the foot-weight thing, I've always taken this as hyperbole rather than myth. It _is_ disproportionately important to insulate the head.
If the claim were that the head loses 45% more heat than the equivalent surface area of the rest of the body, then it might be close to true.
0 second in. What is this, a bite sized 16min video!
My version of a Short!
something something inefficiencies of radiant heaters....🤣🤣
Cover everything and you won't get cold. Got it.
Doesn't convection play a disproportionate role in the head? More so if a hood if you covered the neck as a consequence of covering the head?
Little insulating fat on our heads? You’ve never met my family
😆
Love your videos but you didnt disprove this one. You in fact made a case for it being correct. Fact is head cannot slow flow to it like fingers and head is disportioned for size to amount of veins and loss coupled with no fat layer. Growing up in the cold we spent many a days in the cold simply wearing boots, gloves, hats and a jaxcket. As long as those are covered you stay warm. The head especially
He disproved the 40%-45% heat loss through the head, not that the head has overproportionate impact. In fact, it has around 40%-45% overproportionate impact compared to its surface area.
" Growing up in the cold we spent many a days in the cold simply wearing boots, gloves, hats and a jaxcket." If the number were correct, you would freeze as much without a hat as without pants. Do you?
@@eanredur9920 no he did not he read off some study and made up his mind. He didnt prove it true nor false. And no you would not freeze with out pants. You get the head has less fat than legs. Legs can slow/with hold blood head cannot. Between thos 2 items is why head is vital. Its a giant radiator. Legs are not. Blood flow in legs are insulated.
@@ironpig701 I won't fight you about that, as he truly did not prove anything in a mathematical sense. But for everyone who "asks" a question, there are usually a few more who also did not understand, so let me try to explain it a last time:
Army Manual: 1:29 is the myth (or source of the myth) he wants to disprove.
2:28 gives the paper for the next bits of information, it is a collection of myths and the sources why they are wrong.
3:58 The study the army did, put subjects in arctic suits but without hats, under that circumstances, 40-45% heat loss went through the head. I could not confirm the source for that as I have no NYT subscription and I won’t get one for this.
4:44 The study that brings in most of the meat: doi:10.1152/japplphysiol.01241.2005 for your convenience.
The methodology seems good, it could use more test subjects to claim more precise numbers and maybe even break it down by gender and body fat percentage. But that would need more funding. How comparable still water is with moving air stands to discuss, he discusses that from 6:55 on.
One thing he does not discuss is that water reduces the insulation that hair provides to (near) zero, so slightly less heat loss over the head compared to the rest of the body could be expected in air.
6:20 with only 8 test subjects, those precise numbers seem far-fetched, and they could very well be equal, but blood flow to the head being more important than to the limbs, as well as the later presented impact on body core temperature makes it seem fitting.
Back to the results, Figure 3 from the linked paper is visible at 5:59, and it shows most of what we need. Assuming the data is correct, we can see that the impact of submerging the head is by an order of magnitude lower than exposing the submerged body. The difference from body exposed head in and head is 10% (keep in mind that one arm is at least partially over water for the measurements, so the proportional surface increase is a bit more than would be expected) for ~7% increased exposed surface. As told before, there are some good explanations for that and while the N is low, it is enough to make an educated guess.
About the subjects, they were male with on average 22.8% body fat (SD =6.5), so an unnatural lack of body fat like in bodybuilders is not the cause for the data.
As you seem to care about the statement about the hat, not about his secondary discussion about core temperature loss, I will stop shortly.
Just to make sure you got this point, the head's impact on core temperature is not proportionate to its surface area nor to its impact on total heat loss. Some of this may have to do with the water, but to prevent hypothermia, it is indeed more effective to wear a hat than to wear gloves (comparable covered surface area) though that increases the risk of frostbite.
The useful part ends here, the rest is about your statements because they irritate me with how wrong they are.
"You would not freeze without pants" is answered above and in detail in the video. If you freeze without a hat, you would certainly freeze without pants. Maybe try it for fun next winter.
"...the head has less fat than the legs." that is not relevant. The measurements they did measure the result, they were no simulation where arbitrary factors could be set. Fat potentially protects core temperature, but anything beyond that would need a citation.
"Its (the head) a giant radiator" The head makes up ~7% of the body surface and has a roughly spherical form, the form with the least surface per volume. The legs, that "are not giant radiators" make up a cumulative ~40% of the bodies surface and are roughly cylindrical, a form with much more surface per volume than a sphere. Granted, they probably have better insulation compared to the head.
I have no Idea how fat a "normal" person is in your mind, but I assume ~20% BF in a healthy adult human male. At that stage, there are no massive deposits of fat anywhere on the body.
@@eanredur9920 again he didnt disprove it. Took a myth and another myth and did a bunch of mumbo jumbo and said a bunch and diidnt prove a thing
I did not see any reference to sweating. Most folks heads sweat a lot, particularly with exertion. It does not appear in those studies that sweating is taken into account from an exertion phase to the potential of sitting around stationary evaporative cooling in a demanding cold environment. Likely of some relevance to this discussion as well as having a disproportionate effect. For example, dripping from your forehead with sweat in cold to freezing conditions say shoveling snow off your roof then taking a break. A hat maybe the game changer in terms of rapid, uncomfortable evaporative cooling in the head game, and physiological plus psychological response to the uncomfort chill. This could be a test in itself.
even in the manual the phrasing implies that the unprotected head was examined against a protected rest of the body. People reading an equivilency from it was just a failure of reading comprehension.
A small amateur fact check on the fact check of the fact check: the mentioned diving reflex is barely there in average adults, so you shouldn't factor that into the equation. Second: anecdotal evidence seems in favor of the original claim, though the exact numbers may be a little lower. I can (actually have done so for many hundreds of miles) hike in freezing weather with short pants and a t-shirt, but take my beanie away, and I'll be shivering within minutes. Third point: if you talk about heat conductivity, you also need to talk about wind and moisture. In a humid environment a little above freezing, the wind chill will multiply the heat loss massively. So in summary, I wouldn't say the numbers in the initial claim have been disproved. The scientific setup that got them may have been, but then, it's an "up to..." statement which leaves a lot of wiggle room. That said, I always enjoy your videos and that you question ingrained belief, as that is how new solutions to old problems get found.