Hmmm... what struck me is that this effect is local, i.e. the skin cells exposed to sunlight will store less fat, and the places usually prone to excess fat accumulation will rarely be exposed to the sun, even in summer. Of course, some sunlight will probably go through a t-shirt, while it certainly won't get through several layers of clothes...
I've seen this number given before but I have literally never seen someone get a sunburn through a t-shirt. I've seen plenty of people with awful, terrible, red, peeling burns that required a trip to urgent care on their arms, and their torso is completely fine because they had a tshirt on. Is SPF 7 really all that's required? I usually use SPF30 sunscreen but it seems like that's overkill by a significant amount.
edit: UPF vs SPF is a distinction I hadn't made before I guess. Is the difference in effectiveness that large? Does traditional sunscreen offer UVB protection also, but it's not advertised?
I have a very sensitive skin. Unprotected in full summer sun (latitude 51 north), I'll burn within 15 minutes. In typical hiking attire, only my hands are in the sun, and I keep them in my pockets a lot of the time. My cheeks and lips receive only indirect sunlight, the rest is covered by a hat, sunglasses and a beard. In this attire, I've had sunburn through t-shirts a few times. They are never too bad, though, as I'll overheat way before I burn.
In non-fully protected clothing, something else burns before my chest has the chance to. A major problem with sunscreen is that it degrades over time, and is severely affected by sweat and abrasion. I've read that you should be reapplying every 30 minutes. I typically don't reapply nearly that often, so some parts of my skin are not fully protected. Once those start to burn, I leave direct sunlight, so the skin under my t-shirt (which has consistent coverage) never really gets the chance to burn.
I guess it depends on quality/thickness of T-Shirt. The cheap value-weight t-shirts you get at the supermarket is almost transparent if you hold it up to the sun. Heavy-weight t-shirts that are just a bit more expensive you can't see through at all and never got a sunburn through those.
Maybe as a possible help/hint. There are theories that you get sunburned more if you wear glasses. Something with a part of the region that does some kind of hormonal regulation.
I'm not a hiker but I do cycle and a few times I was exposed for hours to direct noon sunlight. The contrast is clear, exposed skin is red and irritated where the skin under the clothing is white and unaffected. Any kind of synthetic clothing has a greater amount of sunburn protection when compared to cotton but most of the specialized gear comes with additional UV50+ protection.
'Tech' fibers such as capilene for shirts do a great job without making you absolutely miserable like cotton would in the heat. For multi-hour mid-day hikes in the middle of summer (>100F daily temperatures) I wear my 50 SPF 92% polyester/8% spandex long sleeve hoodie. It's white so it reflects heat, and the synthetic mix allows it to breathe and be flexible. As it gets soaked through with sweat, it does tend to retain more heat, so it takes careful planning to find shade and dry off.
'factoid' means that something is fact-like, not that it is a tiny fact. Assuming of course one cares about linguistic precision. If you're the kind of person who uses 'literally' to mean 'figuratively' then you can ignore this, I make no value judgement.
Yes, in the same way that 'literally' also means 'figuratively', which is to say that colloquial usage of the word is incorrect as regards it's intended meaning.
Whether or not that is a useful distinction is subjective.
I disagree. By surrendering the meaning of words we lose the ability to communicate precisely. That may well always be a losing battle, linguistic evolution being what it is, but that doesn't mean it isn't worth resisting.
I'm ginger, as white as can be without being albino. I got a second degree burn on my shoulders through a t shirt. It was field day at school, spent 8 hours in the sun with nothing on my shoulders except a cotton T. Literally had dozens of bubbling blisters. SPF 7 for me means about an hour tops, not 8 hours.
Closeness doesn't matter, I suppose. Make a t-shirt partially wet, hold it in front of some light source and you will see that the wet parts are much brighter. This will probably be the case too for UV light.
Different light wavelengths may penetrate a given material to different degrees. We'd need to know the relative differences in those rates between UV & blue spectrums in order to evaluate whether a typical t-shirt would negate the effects observed in this study.
While we're in the topic of examples, does Usain Bolt count here? I just can't believe the coincidence that the fastest man on the planet would carry that surname. The thing with Bolt is that, not only did he choose that field, he is also biologically gifted to achieve those records. What are the odds, come on! (And I looked it up, Jamaica is an English-speaking territory, though with a creole.)
In more personal examples, in my freshman year, I met a fellow freshie whose name is "Justice", though he is more often referred to with a nickname I now forgot. He was in the Political Science program, on track as a---you guessed it---prelaw degree. He would preempt introductions by claiming his name has nothing to do with his choice of degree program. I don't know if he did manage to enter the bar but "Attorney Justice" sounds as absurd as a superhero name to me. I wonder how he's living up to his name now.
I live in the north of Sweden where we don’t get a lot of sunlight. Not many fat people here compared to other parts of the world where people get a lot more sun exposure.
Something to consider would be local adaptations the emerged over very long periods of time. Most US residents come from a lineage that is (relatively) very recent to those lands.
Also important to note that the US climate is significantly less homogenous, meaning that a somewhat universally high obesity rate is not going to be explained to a large degree by local climate. IIRC, relative obesity rates drop by roughly 40% for individuals with a college degree and in general correlates highly with socioeconomic factors in the US.
You likely have to look at this like "all else being equal" meaning you can't just say look at obesity rates in US state with lots of sun and look at low obesity rates in this dark country. There are many, many other factors at play.
My work has brought me to live in a few different cities in Europe for a year or so.
You might be trying to compare it to countries with unhealthy eating habits.
Swedish people are definitely a little chunkier, on average, compared to their Mediterranean neighbors. Not FAT, but a little wider. Now there's genetics there, as well as cultural difference, cuisine differences, etc... so any conclusion would need to be tested.
Swedish people are educated, aspire to healthy lifestyle and can afford good food. Article, imho speaks about survival mechanisms which aren't so visible/ so active/useful in times where food and protection from cold are abundant.
You are already adapted to the climate of Sweden, meaning you have a lighter skin and your body uses sunlight more efficiently, because it's scarce. This is epigenetics in action. This could be problematic for people who originate from a more sunnier climate and have moved closer to the poles in the hemisphere, or to people who don't go outside. Their body expects more sunlight, however they get less, which could trigger more fat storage.
I think to a certain degree we can adapt to the amount of sunlight at a young age, or even in the womb. Just as we do for food scarcity, see the Dutch winter famine [1]
This article seem to point into the direction of epigenetics. [2]
Lack of sunlight is usually also correlated with cold - and being exposed to cold makes you burn fat fast, to maintain your body temperature. Which might be the reason for the finding in the first place.
But the article is proposing the opposite. "Lack of sunlight makes our cells store more fat."
I would say that being in a cold place makes you eat more. And being only sporadically exposed to the cold could somewhat trigger this evolutionary instinct of storing energy without the expected proportional increase on energy expenditure. Long term, fat accumulates.
Notwithstanding, the brightness level outside even in overcast, in lumens, is still much higher than it is indoors. That lack of exposure has a negative impact on the circadian rhythm, mood etc. Exposure to the eyes is more important than exposure to the skin.
My non-scientific interpretation is maybe this has more to do temperature tolerance for individuals than weight gain? Perhaps the sunlight exposure only affects a very small close to surface level of fat and that's it?
Yep-- Colorado has, on average, lower degrees of poverty and higher levels of education than the national averages. Factors that research indicates are well correlated with obesity. These are more likely factors in their low obesity rates than the direct metabolic impact of local climate.
It local climate has an impact, its somewhat temperate nature probably plays a large part: It has a fair amount of sunshine but doesn't reach the peak temperatures of other high-sunshine states, which probably contributes to the local culture of outdoor activity, and outdoor activities are going to burn more calories.
"It has a fair amount of sunshine but doesn't reach the peak temperatures of other high-sunshine states, which probably contributes to the local culture of outdoor activity, and outdoor activities are going to burn more calories."
It's a simple, true enough fact to make active people move to and live in Colorado, which they do, and which in some part has to impact the overall averages.
As I sit here by the beach in Phuket, I dread returning to the Netherlands.
Nature, sun, water, and good food all encourage me to be active. I’m way, way healthier than one month ago at home.
Regardless of the mechanisms at play, life in a warm coastal area is undoubtedly better for some (all?) humans than dark cold wet featureless environments.
I make sure to go out every day. Unlike doctors' recommendations, I never use sun screen unless I know I'm going to be exposed for hours. I never get burned. I once had a PCP who told me I should alway put sun screen, even on my ears, when going out when it's sunny. I found this suggestion ridiculous. I do understand the skin cancer risks associated with sun exposure, but people need to be exposed to sunlight, just don't be stupid about it (e.g., sitting under the sun for hours to get a tan)
We had to put our dog to sleep a few weeks ago. We've barely left the house since. I definitely want to get out more, but without canine motivation it's been very difficult to remember (Adult executive dysfunction disorder, aka ADHD)
Like with most things moderation is key. Your body doesn't need excessive amounts of sunlight, just enough to fuel it's biological requirements.
I don't have anything against sunscreen, but as someone who lives in the UK I find even on the hottest days of summer I rarely need it. However, this last year I was out in the sun during a heat wave and figured I should probably apply some sun screen on this particular occasion just to be safe. The only place I didn't apply sun screen was my ears and that was a mistake I won't be making again. My ears were extremely sore and peeling for weeks after that. Your doctor is giving good advice imo. Ears are surprisingly delicate and tend to be constantly exposed to direct sunlight from above.
I agree with you that it's good to get some sun exposure every day though. I'm aware in some skin care communities they take sun avoidance to the extreme and won't even leave the house on an over cast day without applying sunscreen. Some won't even go near windows. Again, it's all about moderation.
In practice sunscreen use seems to have minimal impact on vitamin D production. There has been several studies looking into it and in a lab you can measure the difference, but at the population level it doesn’t seem important.
Hunch is that the fashionable advice to cover yourself in sunscreen every day regardless of how long you'll be in the sun or how sunny it is will be looked back on as insane in a few years. It's amazing how many SPF products are now included in people's daily moisturisers regardless of time of year, proximity to the equator or life-style.
You've thought this through, and I don't mean to detract from your point. Something else to consider - photo-aging is real, and is easy and quicker to observe than skin cancer. It's a cumulative effect, and by the time someone's in their 30s, their relationship with sun and sunscreen shows.
I know. I once saw an interview with a women in California in her late 20s I think, who got kidnapped when she was a child and barely left the house for years. She looked so young because of her skin.
I'm aware and do it in moderation. I usually wear a hat to protect my head and part of my face. Also where I live (New England) the sun is not as strong as in some other places.
Me too. I expend so little time on the sun that it seems pointless. It might make more sense for me to use a protective lotion to protect from screen burns.
But I'm cycling frequently lately and I do have a pretty clear contrast between my torso and arms colors. So...
True but those wavelengths will maintain your circadian rhythm if you time it correctly. See the Huberman podcast on this: https://youtu.be/nm1TxQj9IsQ
The relation between number of fat cells, how much fat the body attempts to store, and the resulting urge for consuming calories is somewhat complicated, right?
In other words: is fat storage purely a response to diet, or is existing excess fat tissue also a driver in eating excess calories?
Because if it were purely a response to caloric input, then one could also posit that exposure to sunlight might increase visceral fat storage: the fat not stored under the skin would stil have to go somewhere.
Well, it's complicated. You cannot compare people living in Urban ares like NY/Toronto/etc. to people who are driving everywhere in Florida. You need to find comparable populations and it's not easy.
So humans work like bears makes sense. Probably food was lacking scarse in historic times during winters. Body stores fat during summers for later use in dark winters.
Theoretically data wise that works, since people closer to the equator are less likely to be obese. But the reason for this is more to do with economics.
There's a lot of full spectrum lighting options out there since they are used for some other reasons (treating seasonal depression, etc.). Personally, I like this one:
https://www.amazon.com/gp/product/B003XDIPNA
A lot of the products require you to sit right next to or put your face right next to them. Think like a makeup vanity. Instead, with that one, I can just set it up right next to my bedside/desk/wherever I'm going to sit on my laptop for the next 16 hours.
I would also like to know. Did a little searching around a few weeks ago and couldn’t penetrate the marketing fluff to get to a trustworthy recommendation.
> A breakthrough study by University of Alberta researchers has shown the fat cells that lie just beneath our skin shrink when exposed to the blue light emitted by the sun.
I'm going to guess no. Blue light therapy maybe, if that's a thing.
They compare to wavelengths that cause pigmentation changes, which occurs only in exposed areas of skin. So it may be that results would be lacking if you are simply outside & normally clothed.
It is still a significant finding: Intricacies of our metabolic processes do not seem extremely advanced, and this gives further clues about them. Although it does not appear to be something that would be a major contributor to weight loss. (wouldn't any screen addict have exceptionally thin faces?) Nonetheless, I'm sure there's some eager snake oil sales folks already working up marketing for the latest fad weight loss schemes.
As a redhead, this seems like a very big difference. I'm genetically way more likely to get cancer from sunlight than a non-redhead but also produce more vitamin d with less sunlight.
there is a school of thought that the vast majority of skin cancers are basically harmless (squamous cell and basal cell carcinomas), and that perhaps even the more of these carcinomas you have, the more sunlight you have received and so therefore the more vitamin D, and that you will therefore be healthier than someone without those carcinoma...restated, the more skin cancers you have, the healthier you are, in general...
