Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
31 May

A Primal Primer: Brown Adipose Tissue

Last week’s Dear Mark discussing cold thermogenesis got some of you asking about brown adipose tissue. It’s a topic that deserves a full-fledged Primal Primer, especially since the idea of “good” body fat, a term many use to describe brown adipose tissue (BAT), is a foreign one. I mean, we’re talking about body fat here. Who wants it? Everyone I know is trying to get rid of their adipose tissue, not obtain more. It’s what brings many to this blog and what initiates this grand journey toward health and wellness. Even the people who say they “don’t care” about how they look would rather not have excess body fat, if only because it’s a marker of poor health or hormonal disregulation. We might acknowledge that we technically “need” some body fat to survive, but most of us will pass on any more than is absolutely necessary, thank you very much.

So whenever brown adipose tissue is invoked as the “good” kind of body fat, a body fat that cannibalizes other body fat, flabbers audibly gast. Is such a thing even possible?

Yes. Brown adipose tissue is very different than white adipose tissue. While white body fat can be regarded as an endocrine organ involved in the release of hormones, it doesn’t “do” all that much. It leads a pretty sedentary existence. Brown adipose tissue is metabolically active, however, consuming fat and glucose, increasing metabolism, and generating warmth for the organism as needed. Animals without the ability to shiver or tie scarves around their necks – like rodents and newborns – have lots of brown fat, because that’s how they stay warm – through “non-shivering thermogenesis.” Brown fat is dense with mitochondria, the power plants of cells which normally use fat and glucose to produce ATP. BAT mitochondria use fat and glucose to produce heat, rather than ATP. Thermogenin, or UCP1, is the uncoupling protein within the mitochondria that enables BAT to oxidize fat without producing much ATP.

Until quite recently, researchers assumed brown fat was mostly absent in adult humans. And if adults did have any, it was probably just a vestige from childhood with little actual functionality. In actuality, recent studies show that men and women can and do have significant amounts of brown fat, usually located near the neck, the chest, and the upper back, with women tending to have more than men. Rather than being inert, this adult brown adipose tissue is metabolically active with some interesting potential effects:

That all sounds pretty good, but how do we act on this knowledge? Is there anything we can do to start utilizing brown adipose tissue in our pursuit of health, leanness, and general Primal awesomeness? Maybe.

If you want to activate BAT, you have to get cold. Seeing as how brown adipose tissue’s primary function is to maintain body temperature, cold exposure activates existing brown fat – it presents the necessary environmental stressor to tell brown fat to start burning triglycerides for energy. A recent study (PDF) found that while exposing both lean and overweight men to “mild cold exposure” (61 degrees F, or 16 degrees C) activated brown adipose tissue in 23 out of 24 of them, thermoneutral temperatures resulted in zero BAT activity. Your brown adipose tissue doesn’t have much to do on a nice, warm day – nor, for that matter, on a miserably cold day so long as you’ve got the heater on inside.

Get cold, but not so cold that you can’t stand it without breaking down into a shivering mess. Brown fat keeps us warm up until the point of shivering, after which the physical act of trembling warms us and brown fat is deactivated (or down-regulated; it’s not clear whether it gets flipped off or gradually fades away). If you want to activate your BAT and only your BAT, don’t get so cold that you begin to shiver. Eventually, of course, your “shiver set point” will improve, you’ll get used to the cooler temperatures, and you’ll be able to tap into your BAT at lower and lower temperatures. Shivering also burns calories in its own way, but, well, shivering is kind of unpleasant and awful and it requires far lower temperatures. Go for goosebumps.

Although cold exposure is definitely the best way to activate brown fat, there’s also evidence that a person’s brown fat stores mediate the amount of energy they store after eating. Whenever you eat something, heat is generated, both from the physical and enzymatic breakdown of the food and from “diet-induced thermogenesis.” In patients with lower UCP1 expression (remember, UCP1 is the protein that enables combustion in the brown adipose tissue), the thermogenic response to a meal is lessened; and patients with confirmed brown adipose tissue generate more heat in response to a meal than patients without brown adipose tissue. Since that heat comes from energy that is not being stored, a greater thermogenic response to food means less (bad) body fat accumulation.

All this revolves around the activation of existing brown adipose tissue. While that’s important, what about creating new BAT? There are two candidates – chronic cold exposure and exercise.

In rodents, temperature to which the animal is chronically exposed determines the total amount of BAT on the body. Rats in a heated lab will have less brown fat than rats living outdoors. Humans, even those living in cold climates, are rarely exposed to the cold weather. They sleep in heated homes, drive in heated cars, shop in heated department stores, and bundle up with multiple layers for those fleeting moments spent outdoors. It’s even been proposed that the advent of central heating is related to obesity. I suspect that the total amount of human BAT also depends on chronic exposure to cold, especially since one study (PDF) showed that outdoor workers have more BAT than indoor workers. Acute exposure activates, chronic exposure creates.

Irisin, the “exercise hormone,” appears to convert white adipose tissue to brown adipose tissue. As irisin increases in a rodent’s blood, energy expenditure increases without an increase in movement or food intake, suggesting an increase in thermogenesis mediated by the converted WAT. Humans also make irisin in response to exercise, so this could work for us, too.

I don’t think we can ignore brown adipose tissue as a partial player in the metabolic mess we’re in. It’s not the one key to solving the obesity epidemic, but neither is anything else. It’s a piece of the puzzle, a contribution to the whole mess, and it’s completely plausible to think that people are fatter than they have to be because they’re too dang warm all the time. Sure, people have always avoided the cold, whether through central heating or animal pelt, but the way we avoid it today is way different – and far more effective. At any rate, it can’t hurt to give it a shot.

Hopefully, one of these Saturdays I’ll be able to include a recipe for stir-fried veggies in the rendered brown fat of pasture-raised hamster (sorry, hamster lovers; I had to pick a rodent). Until then, let’s hash things out in the comments. Tell me about your experiences with cold exposure, brown fat, and weight loss, or weight gain, or your plans to experiment. Take care!

You want comments? We got comments:

Imagine you’re George Clooney. Take a moment to admire your grooming and wit. Okay, now imagine someone walks up to you and asks, “What’s your name?” You say, “I’m George Clooney.” Or maybe you say, “I’m the Clooninator!” You don’t say “I’m George of George Clooney Sells Movies Blog” and you certainly don’t say, “I’m Clooney Weight Loss Plan”. So while spam is technically meat, it ain’t anywhere near Primal. Please nickname yourself something your friends would call you.

  1. Wait, WTF? I grew up in eastern Washington (snowy) and the San Francisco bay area (foggy and wet). When I moved to Sacramento (hot as hell for six months of the year), I gained 100lbs. I moved back to the bay area and lost 70lbs doing basically nothing different. I got pregnant and gained the 70lbs back, then moved back to Sacramento and could not get the fat to budge until I found paleo / primal. For years, I’ve joked that the hot weather makes me fat.

    Now… Are you telling me that the hot weather really is making me fat?!

    em wrote on May 31st, 2012
  2. This past winter, I kept the house pretty cold, like around 55. It wasn’t for my health: I have a wood heater with heat pump back-up, and I just didn’t want to build a fire on some days b/c it took time. But I didn’t want to pay the electric company either. I got used to it, and I did lose some weight. Some of that weight has crept back on this summer, but not much. I have also noticed that when other people are cold, I am not: I was on a plane recently when most people felt too cold, but I felt fine. Maybe my brown fat kicked in and warmed me up.

    shannon wrote on May 31st, 2012
  3. Huh. I always complain about the cold. Would anyone know why I would generally feel colder (i lived a year in south Texas but that was years ago) than most people and prefer warm climates, and also I’ve noticed on mornings when I eat eggs fried in coconut oil with Bacon or fish and a whole sweet potato I feel warmer and and seem to have more energy.

    ash wrote on May 31st, 2012
  4. Amazing…..So things actually make some sense now. I was wondering why sometimes even in ketosis, some people still gain or lose weight while trying to maintain (regardless of water retention) Mark is the man!

    LowCarbMaster wrote on May 31st, 2012
  5. When I overeat I feel like I’m burning up from the inside out. I feel like I could spontaneously combust, and I’m fat….. My husband is thin and never feels hot after a meal. So I don’t know, it’s opposite in us. I’m going to start taking cold baths/showers before bed and see if that can speed my weight loss along. I hope! Atleast it should make me sleep better since i’m also burning up when sleeping.

    K wrote on May 31st, 2012
  6. Nice, reading this from the cold shower.

    Wyatt wrote on May 31st, 2012
  7. Have been doing the cold shower (after regular hot shower) every day for the last 2 months. Also, taking advantage of our chilly mornings here in the NW. Drive around with the windows down, get to goosebump stage. The cold showers have become very addictive, they make me feel so good, but I have not really noticed a reduction in fat, still have that last 10 pounds to shed and it is going pretty slow.

    meegeek wrote on May 31st, 2012
  8. maybe we should alternate cold and hot showers. any advantages to hot showers, other than the enjoyment?

    pixel wrote on May 31st, 2012
  9. I am another one of those “crazy Russians” living in the U.S.:-). Every night after a hot shower I dump a bucket of cold water on my neck/ back. It feels AWESOME and I NEVER get sick.

    Julia wrote on May 31st, 2012
  10. Here in the far north I spent 3-5 hours per day out in the snow and wind every day, learning to track and trap animals this winter, running between traps. Now (trapping season is over for 2 months) when I eat a good sized meal after a day of work I get very noticeably warmer than before, even though it is well into spring. This article explains why. I eat a god variety of fats – free-range eggs, grass-fed free-range butter, extra-virgin coconut oil, fat from free-range animals and wild game, fish eggs and fatty fish, olive oil. Eating those types of fats may have something to do with the acumulation and activation of brown fat. My weight and body fat percentage (8-10) remained the same. This makes sense when you look at Inuit children with T-shirts on in 20 degree F weather (or colder). Their diet includes a high percentage of seal and walrus blubber, which is absolutely necessary for their survival. Surely there is some genetic adaptation involved as well.

    David Marino wrote on May 31st, 2012
  11. I wonder about the fat soluble toxins of industrial society, and their effect on accumulation and activation of brown fat, and how effectively daily sauna therapy (with cold shower breaks) can detox the brown fat, as it does with white fat. It probably does a good job – the Finnish people seem to have proven that.

    David Marino wrote on May 31st, 2012
  12. Now I understand why, after going primal I actually feel hotter and “emit” hot radiation! It sounded weird that while losing fat I was starting to feel hotter than before. Now it sort of makes sense. I used to justify this by saying that fat burns hotter than sugar… maybe it’s just the brown fat!

    BTW: in my house in winter I have between 10 to 16 C degrees! I must be full of BAT!

    Lard on!

    voingiappone wrote on May 31st, 2012
  13. I’m in northern Illinois and it gets quite cold here in the winter. When it gets below 30, I get super grumpy but anything above 30 feels fine. Even this last winter, walking to class everyday (20-25 mins. one way) I managed to gain weight (both muscle and fat). I’ve always joked that my Mediterranean genes (my dad’s mom is 2nd generation) demand warmer weather and I tend to maintain weight easily in the summers. Last summer, I started utilizing cold showers and my body fat dropped pretty quick and my recovery time from workouts was also improved. I’m doing the same thing again now and am noticing the same effects. Tomorrow is measurement day though – yikes!

    Emily Mekeel wrote on May 31st, 2012
  14. sitting on my porch, after reading this post, the cool breeze that would normally chase me inside takes on new meaning! mark, thanks for making me smarter, tougher and healthier everyday!

    primal aly wrote on May 31st, 2012
  15. Here’s my experience for what it’s worth. I grew up in Edmonton,AB (if you’ve never wintered there, look it up on a map to fully appreciate how far north it is), and was accustomed to almost always having goose bumps on my arms, indoors or out. I eventually moved to a warmer place and my cold tolerance is frequently remarked upon by people who weren’t brought up with the sort of winters I had to endure. I’m often the lightest dressed in a group. People point out my goosebumps and tell me I must be terribly uncomfortable, but it actually feels just right to me. I feel very uncomfortable on hot summer days. I’ve always been skinny.

    kate stone wrote on May 31st, 2012
  16. Ooh… what can those of us with absolutely no tolerance for the cold do? :( If I’m in 16 degrees C without a jumper, I’m probably shivering. Meanwhile, I’m relatively fine on a 40 degree C day.
    Do we have to start much higher in order to lower our set point?

    Audrey H wrote on May 31st, 2012
    • okay Canadians…16 and 40 deg. C means nothing to me (though I can’t speak for the rest of Americans) I’m feeling too lazy to go to an online converter to see what that is in F.

      Milemom wrote on June 2nd, 2012
  17. I’ve lived in the central african rainforest with hunter gatherers and it does get cold. At night under the forest canopy or in a storm you need a fire to keep warm. I was often wrapped in a jumper while my friends would still be in only shorts, what with not owning any jumpers. Plenty of opportunity to get cold!

    Olivia wrote on May 31st, 2012
  18. I’m a swimming teacher and in the summer I have to spend 4+ hours being cold in the water (air conditioned indoor pool) a day. I find I feel more energized afterwards and I swear my metabolism speeds up. Wonder if this is the reason… interesting!

    Alex wrote on June 1st, 2012
  19. Last year I went on a retreat in which we trained ourselves to go swimming in the North Sea, which had temperatures right at the freezing point (it was February). It was amazing! I would plunge into the freezing water, and within 10-20 seconds, I felt WARM. I would then swim around a little until I started to feel cold again. Then it was time to get out. On days when I did this, I felt incredibly warm and energized for the rest of the day. I have no idea what it did for my metabolism, but it made me feel fantastic!

    Stephanie wrote on June 1st, 2012
  20. Boy am I now glad I joined in the Ocean plunge at PrimalCon. I just knew there had to be even more good reasons to do it.

    Gary wrote on June 1st, 2012
  21. Brown Adipose Tissue doesn’t sound very appealing… maybe we need a mascot?

    I’m thinking….. BATman 😀

    Dave wrote on June 1st, 2012
  22. Makes sense to me. I tend to lose weight in winter and gain it in summer, which is the opposite of what is supposed to happen.

    Louise wrote on June 1st, 2012
  23. I live in Minnesota, and I always weigh the most in the winter. I weigh about 5-10 pounds less in the summer- my weight has been exactly the same range cycling between winter weight and summer weight for 20 years (excluding pregnancies).

    I always attributed it to being slightly more active in the summer months, but now I wonder if it’s because I FREEZE all summer long in the over-air conditioned offices I work in. In the winter the offices are warmer, plus I’m wearing heavier winter clothing.

    Kirstin Juhl wrote on June 1st, 2012
    • how does one gain BAT? i’d like to get some to be less cold (i’m always cold). it is not clear to me from this article.

      pam wrote on June 10th, 2012
  24. I took a little swim in Lake Zurich, Switzerland last Monday evening, water temp about 17 C. I stepped in slowly and let everything adjust, made sure limbs in good working order and took off! It felt pretty great! It was easier to get past the adjustment stage thinking of it as an experiment in activating brown fat. Stayed in about 20 min. moving moving moving. Might try to do that once a week. For the past 6 months I have been ending a warm shower with a cold all over blast and I really believe this practice has helped fend off some of the common bugs one is exposed to, along with 80/20 primal eating habits. Still working on those last kilos, but feeling well!

    Jen wrote on June 1st, 2012
  25. Brock University In Canada has invented and researching cold suits for obesity and diabetes. There was a radio doc done on CBC about a year ago about these studies.

    Nicole wrote on June 1st, 2012
  26. I have started trying to expose myself to the weather as much as possible. One it makes me feel alive. I took a hike in 50 degree rain a couple of months ago and loved it. But also I have a job where I am repeatedly exposed to the weather and if I embrace it it is a lot easier. When cold weather came last fall I made it a point to acclimate and it made a huge difference. Its amazing what your body will do when you apply the right stress.

    CMHFFEMT wrote on June 1st, 2012
  27. I live in Chicago which can be very cold. I am a winter/snow enthusiast and plein air painter. I paint outdoors even in winter – standing for hours.
    I am a weightlifter and primal eater.

    I have experienced thermogenesis “sometimes” after being out painting (and properly insulated). 3 hour naked bikeride on a 62 degree evening only made me cold and shiver for a week afterwards.

    Women supposedly have more BAT. Perhaps it activates differently than men. And hormones seem to be the name of the game here… different for men/women

    If BAT is being activated I cannot consistently produce a thermogenic event. I’d love it to be true but for now I think it’s still in the theory stage (Yes, I’ve read Dr. Jack Kruse’s stuff). Chicks are different yo!

    Beck wrote on June 1st, 2012
  28. Pasture raised hamster eh? Hmm….my house is currently being invaded by chipmunks (free range!). I wonder how they would go with a side of asparagus…

    Jody Ruttan wrote on June 2nd, 2012
  29. I have been doing vasper for a month. one exercises on a recumbent bike with COOLED compression cuffs around thighs, arms, core. The thoroughly researched effect is to raise lactic acid and consequently growth hormone. Results? deep sleep, weight loss, muscle development, increased immune function, a pronounce reduction in hot flashes. that is for normal folks. people with diabetes and thyroid dysfunction as well as spinal cord injury patients, auto-immune patients (RA, MS, DM) all see huge gains in performance. This, folks, is NOT bullshit. Just follow Peter Wasawoski’s 30 years of research for NASA…..

    ChiroLisa wrote on June 2nd, 2012
  30. Hi Everyone… I have news for you…Air conditioning and cold temperatures add to body fat and more yes more adipose tissue. There have been several articles (“Outside” magazine, Atlanta Journal last summer on that very subject. I can attest to the opinion of more cold = more fat and slugishness. Am I a heat-loving lizard? Probably, thank you very much !

    Lee Kerger wrote on June 3rd, 2012
  31. Where’s the darn Like button?

    Elizabeth R wrote on June 4th, 2012
  32. This is great news for me as the AC has been turned on in my office building and it’s so cold in here I’m in a consistent state of goosebumps! YAY cold!

    Jenn wrote on June 4th, 2012
  33. Is it the chicken or the egg?
    Hot people are more likely to seek cold and cold people the heat. Are people spontaneously bundling up MORE and exposing themselves to the cold less? Or have they poisoned their metabolisms with bad foods? I’ve found that a good marker of a healthy metabolism is increased resistance to cold.

    With that said, it sounds refreshing to go on an Alaskan retreat with a big stock of salmon and firewood in a grizzly-monster-proof cabin. Mmm salmon. Stars, snow, beautiful mountains…the smell of fresh pine.

    Olivia wrote on June 5th, 2012
  34. It’s now officially summer here in WA and I just bought a contoured icepack for the neck. I plan to combine with a broad, rectangular ice pack pinned to my shirt for some ‘brown fat training’.

    So I’ll ice the neck, throat, upper back and chest area during the summer when it’s more tolerable) where brown fat is purportedly more concentrated, with hopes of switching on that brown fat in time for winter.

    When considering the options of cold showers of any duration, cold plunges or using ice packs, I realized I would only realistically use ice packs. I can’t even will my hand to turn the shower dial to cold! But, I’ve recently iced the heck out of my lowback/sacroiliac area so I think I can deal with icing higher up. Wish me luck!

    I’m in a PT situation over the last 5 months that has prevented me from anything but the lightest “exercise”. I’ve been Primal/Paleo for 3 months and it’s time to step up my game.

    Massage Team wrote on July 6th, 2012
  35. This seems counter-intuitive, you would think that exposure to cold would cause your body to engage mechanisms that cause it to store extra fat for warmth?
    Or is the immediate need to heat up the body by increasing thermogenesis more important than long-term, fat loss.

    I think I just answered my own question?!

    L wrote on June 10th, 2013

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