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!

TAGS:  body fat

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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134 thoughts on “A Primal Primer: Brown Adipose Tissue”

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  1. Cold showers, dive in the ocean, plunge in the snow, I do it all. 😀

    Exposing to low temperatures has tremendous benefits, you can feel it right away, you feel refreshed, awake, and alive.

    Of course it accelerates the metabolism, because it forces the body to keep up the temperature at its standard.

  2. Very interesting. For about 6 months, I have felt warm after eating anything. Perhaps it’s because of increased brown fat. I haven’t thought of any other good reason for the effect.

  3. Maybe that is why my hot flashes have been more pronounced lately. Since I upped the protein and fat is starting to melt off, they are happening more frequently than they have in a couple of years.

    1. I was about to comment that my hot flashes seem to originate on the back of my neck and lower back at about the waist, and was wondering if the process involved communication with BAT somehow. Very interesting!

  4. I’ve long suspected colder temperatures were better for fat loss. It’s just more difficult to not increase the calories as a result and compensate for it.

  5. This is non-sense! I will enjoy my hot California home and just eat fewer calories! Bogus!

    1. Thank you. Correlation does not imply causation. Isn’t that what we primals are always saying?

  6. When I lived in Siberia the Russians would go outside in 30 below in their swimsuits and dump cold water on their heads. They would also do this before hitting the dacha for a steam.
    They claimed that deliberatly exposing oneself to extreme cold was good for the immune system and overall health.

    1. That’s craziness; although, those Russians are pretty robust people, so maybe they’re on to something!

      1. I’m one of those crazy Russians (though I’ve emigrated), and when I lived in a cold climate, I’d put on my swimsuit and dash outdoors into the snow for just a few seconds – not enough that you’d get frostbite or really start shivering, but just long enough to feel the cold. It feels so good – a very invigorating feeling.

        Now that y’all have reminded me of it, I think I may take myself to the beach and jump into the Pacific with the same goal in mind. The water is pretty cold here in San Francisco.

        1. Im am from Finland and here it is pretty common to jump into an icy lake or bath in snow after sauna during the winter. Sauna is something invented here to bring us warmth during the long cold winter. It is basically a small room with a big furnance that heats the room up to over 190 f. In addition we throw löyly, i.e water on the furnace to generate hot vapor which intensifies the feel of heat as the hot vapor meets the body. Anyway, the idea is to get as warm as possible in the sauna, till you almost can’t stand it, whereafter you dive in the cold lake or the snow. This can go on for hours. Get heated up and chilled down. It is super invigorating and you feel totally refreshed as you where reborn. If you visit you should try it!

  7. In order to see effects from cold exposure, what sort of time do we need to be exposed for? If I want to take a cold shower to promote BAT activation/growth, does it need to be multiple minutes, or will a 30-60 second blast at the end work just fine?

    1. From what I read 10 minutes in the morning and 10 at night is fine, plus the morning cold shower works better than 10 cups of coffee to wake you up!

      1. Nathan, I’ve been doing the ten-minute cold showers, and I realize now that it was because of this comment.

        What had you been reading?

  8. I buy the entire concept as outlined above by I wonder about the universality of the conclusion. The obvious question would be “what about people at the equator?” wherein the temperature never get’s that cold (maybe at night in the desert?). Do these massive demographics have different brown fat systems/ thresholds? Surely they don’t get fat from being warm all the time?

    1. “it’s not the one key to solving the obesity epidemic, but neither is anything else. It’s a piece of the puzzle”

      im sure there are other regional/cultural factors to their percentage of obesity, whatever that may be.

    2. You’re right. It depends on your genetics and what climate you are currently living in. The Eskimos had tons of brown fat! But for the people living around the equator, I’m sure exposing themselves to cold would be counter-productive, but who knows. I would say simply spending more time outside and exposing yourself to non-heated water would do the trick.

  9. I am from Ohio, and no matter what I ate I always maintained a good weight of about 175lbs. After moving to California (because I’m stationed there, soon to return to Ohio), I’ve ballooned to 215lbs and cannot for the life of me lose it (doing everything right). I wholeheartedly agree that cold works, because I spent a lot of time outside in the snow.

  10. This is exciting! I may start taking cold showers! Is there some amount of time we need to spend in cool temperatures to get benefits? Or will every little exposure help some?

    1. Hmmm, I’ve been taking cold showers for another reason. How nice to hear that they are good for more than one purpose.

  11. A cold shower does invigorate but I may not need cold water: I’ve lost almost 50 pounds to date and I get colder easier. Just last night my wife turned the air conditioner down to 70 and I was forced to wear long pants and a light sweater. Man, that was weird because I NEVER get cold.

    1. awww, I’m sure you could have gotten a date without losing the 50 lbs.
      “i’ve lost 50lbs to date”
      oh wait….you meant….haha. 🙂

      seriously though, I think I just read something on his site in about your body omega 6 levels being high if you can’t tolerate cold very well. Maybe look into it. If I find it again, I will post it.

  12. This is awesome! I competitively swam in high school, and was just very active all year round. I was able to consume huge amounts of servings, and not gain any weight (aside from muscle). My swim practices consisted of 4 hours a day during the winter in 55ish degree water. To this day, I am still a phenomenom to anyone I know (with how much I eat, and still don’t gain any fat), I also feel more comfortable in the cold, than the heat. Now I know the science behind my situation. Thank you Mark, love ya dude!

  13. I am cold ALL. THE. TIME.

    My furnace only turns on when I am asleep: my husband knows when I am falling asleep on his shoulder because he says I start to radiate heat. Most of the time, I have cold hands, feet, and am generally chilled unless it’s above 75 degrees. My blood pressure is on the low end of average, but my circulation is without issue.

    Could being cold have anything to do with brown fat? Is it an affect of brown fat?

    1. Please, please get a thyroid panel done. Low thyroid production is so common. Cold intolerance is a huge warning sign. If your levels are off, be careful not to eat raw cruciferous veggies (cabbage family things like broccoli, caulflower, etc), or other goitrogens (like raw strawberries) until you get your levels up. I highly recommend you go to Mary Shomon’s site https://thyroid.about.com/library/quiz2/blthyroidquiz.htm and read about symptoms and steps to getting diagnosed. So many docs are not up to date on proper testing and test interpretation, you really want to educate yourself. Low thyroid can lead to heart disease, dementia, fatigue, insomnia, muscle aches…on and on…it’s not pretty.

      1. Kit and Marion, I love this place, people are so caring!

        It’s funny, because my thyroid numbers are actually irregular and have been since last summer.

        However, my energy is normal (I am naturally hyper), my hair is not falling out, I am not gaining weight (lost 8 lbs when I first went Primal and have stayed at that weight since), and I have felt felt nothing but healthy for years, even more so since going Primal in March.

        On paper, my MD says I have thyroiditis, but I am asymptomatic. I’ve been cold like this my whole life and the numbers just started acting oddly when I was put on doxycycline for Lyme last summer. I got bit by another tick in March and was put back on that nonsense, and guess what? My Anti TPO (for you thyroid folks in the know) was 3100 IU/mL OVER normal. It’s never been that high and I was in the middle of the evil antibiotics course. Coincidence? No way. Symptoms? Still None.

        So, the antibiotic makes my pituitary gland attack my thyroid, but thus far it’s been a tough little bugger and refuses to die. My MD even said that since my hands don’t even tremble (and they should — plus, I should be lethargic, fat, and bald), he doesn’t want me on medication.

        As I said, I’ve been cold all my life and had normal blood results up until last year. I blame the medication.

        So, why am I cold?

        1. Nicole, I have had hypothyroidism for 7 years and can assure you not everyone has the same symptoms. Perhaps cold is all you get? Some people only get one or two symptoms from the list of over 50, some get many.

          Some people lose weight, not everyone loses hair (although I did) and even with the medication and “normal” blood levels now, I’m still a chronically cold person. Bodies are funny, and unique.

          Hope that helps!

        2. Nicole, I’m a little concerned that your doctor doesn’t want to treat you because your hands don’t tremble–that’s not really up to the standard of care and it’s not evidence-based care. Please get a second opinion! Maybe from an internist or endocrinologist. If possible, see one who is not in the same practice as the doctor you have been seeing. Even people who are totally asymptomatic are treated if their thyroid hormone levels are abnormal (with the cold intolerance you actually aren’t asymptomatic even if you had cold intolerance your whole life); and you can be asymptomatic but still experience damage. In pregnancy in particular. Anyway, please get a second opinion!

        3. Nicole when you have problems with your thyroid your hands tremble ONLY when your thyroid is OVERACTIVE.

          Please have a second opinion. Please keep in mind that there is even a petition in progress at the moment where patients with thyroid problems are complaining about poor standards of care from endocrinologists let alone primary care physicians.

          What you are describing sound very similar to how I used to feel. Cold peripheries and becoming hot when I was tired at night.

          If you are becoming hypothyroid, you need to consider a much broader range of symptoms than being “lethargic, fat and bald”. For some women symptoms may be as diverse as “unexplained” infertility, constipation, heavy periods and carpal tunnel syndrome. And when I was in medical school I could not believe how many of my fellow medical students had difficulty remembering which symptoms belonged to overactive thyroid and which belonged to underactive

          Some doctors will hesitate to start thyroid replacement therapy which is unfortunate as you could have your pituitary producing large amounts of TSH which will result in a worsening of the autoimmune problems you are having with your thyroid.

          This is a very complex problem which needs careful thought.

        4. I am very glad that he is not putting me on medication at this point. It is medication going into my body that is causing this problem and my only concern now is the length of time that it is going to take for things to regulate again, because before this second tick bite, I was almost there.

          As I said, I have always been cold and only recently ran into an issue with these numbers, so it is not new. I do not want a second opinion at this point because I do not want to fight with someone who wants to unload a drug on me. I am asymptomatic, so I do not want some synthetic anything in my body.
          If it were not for the lab results, there’s nothing about how I feel that would suggest I am anything but 110% healthy.

        5. maybe you naturally have less brown fat. At one point when I was getting into good shape I was going to research how the special forces dudes learn cold acclimation… maybe you can see what they do and apply it to check for benefits.

          Also, on an aside note: why are eskimos fat if being cold keeps us warm? Arctic peoples also have a good ole layer of white fat to keep heat in. There must be a happy medium.

        6. Nicole,

          i am also cold all the time. i hate being cold.

          i have also been diagnosed with mild hypothyroidism (no hashimono tho) & Raynauld syndrome. but i dont’ have any of the typical hypo symptoms.

          actualy i’m much more cold resistent now after switching the diet.

          but still no way am i going to try cold exposure!

          oh, have i mentioned i just hate being cold? haha


    2. Nicole, have you had your thyroid checked? Feeling cold all the time could be an indicator of an underactive thyroid…

      1. Nicole – you can take Armour which is not synthetic. I have really improved since starting Armour.

        1. What symptoms did you have?

          I am only having problems with my thyroid on paper, so I am sticking to my “let me be” guns. But THANK YOU for the name, I will keep it in mind if I ever develop symptoms.

      2. Marion, tests have actually shown my thyroid being both over and under active. Right now, it’s numbers are fine, despite other numbers being crazy.

        1. Nicole – many (?10?) years ago I had some thyroid tests on the high or low side but within limits. A nuclear anti-TPO test was off-the charts high and an endocrinologist told me that was a marker that guaranteed (in his mind/experience) that I would eventually become hypo-thyroidic – had Hashimoto’s disease.

          I simply did not want to go on a life-long medicine plan and told him I would not as long as my tests remained in the normal range. I did that – but BEFORE they got out of range, I discovered for myself that I was developing a noticable GOITER! A bulge in my neck. Sonograms confirmed my thyroid had more than doubled in size working its little heart out to produce hormones, is my take on it. I was NOT going to risk it becoming worse and went onto synthroid. In six months the goiter shrank in size to the point it is not so noticable (never was HUGE).

          I just want to put this out to you – putting it off is not risk-free if your body / thyroid just isn’t right. Oh, and I too was symptom-free, normal weight, active exerciser, good hair, etc throughout (and still).


    3. Sounds like thyroid. Is thyroid somehow connected to the brown fat activation issue? I wonder.

      1. Sounds like since all this discussion erupted about thyroid we need some more information on the topic. One thing that I’ve noticed is really lacking on most of the paleo websites (which are largely written by men) is coverage on topics that seem to impact women. Thyroid issues seem overwhelmingly to be in the female ghetto… or at least the men are ignoring the fact that they may also have thyroid issues (all those bald guys out there…). In any case, it’s nice to see some folks speaking up about a topic that’s near and dear to my and my family members.

      1. Thanks! I am going to need time to digest that first article! But read it and understand it, I will!

        Through continued experimentation, I have been finding that turning my shower cold every morning is making me more resistant to the cold. My hands are not as cold, and I warm up faster than I used to.

        And I am happy to report that my thyroid is still fine!

  14. I’m having some difficulty reconciling the need for cold with the fact that most of our evolution occurred in central Africa. How could there have been any natural selection pressure for cold in the tropics?

    1. A very fair point. Either…

      1) Brown fat is something we don’t properly understand yet.
      2) The paleo principle/WWGD is a little flawed and we should apply it more sparingly than people seem to do on MDA.

      It wouldn’t surprise if it was a little bit of both 🙂

    2. You have to remember that the Earth hasn’t always been as warm as it is today.

    3. There have been glacial ages where glaciers extended almost to the equator and mass extinctions caused by periods of cold/darkness. Life would naturally have selected for strategies to survive cold.

  15. I am 5’5″ and weigh 112lbs. Have been this weight for 20+ years. I am always cold after eating to the point my fingernails are blue. My BP has always been low (90/60). I live in the desert so I need a jacket when it’s below 80. I wonder if I have any BAT?

  16. I will have to give this a try tomorrow. Quite clean already today. Living in Minnesota, this winter ought to provide plenty of opportunity to test this theory.

  17. I wonder if this explains my annual weight fluctuation. For years, I notice that in winter (Minnesota) I weigh less and soon as swim suit season hits, I gain weight. I do walk several times a week outside in the cold, plus ski and I am always cold. So does that mean I have brown fat?

    Are you sure that the hip-thigh fat we ladies carry is not brown fat – that would be awesome.

  18. My great grandfather used to have cold showers everyday, and when he could have a warm shower he would always finish that shower with a cold water blast for 60 seconds.
    He lived an active, healthy life and lived to 90 years old. His son, my grandfather, has very similar habits and is turning 90 this year.
    This combination of cold exposure and healthy lifestyle is doing my family good.
    Hope my great grand-son/daughter can say the same thing about me.

  19. Great example of the tyranny of public health. A disturbing meta trend in the western worlds public policy. Be afraid!

  20. I have heard a theory that women feel colder than men more often because they have the possibility of becoming pregnant, and thus require a better thermal management system that diverts blood flow from the extremities and keeps in closer to the heart/critical internal organs (or baby). Women also live longer than men on average, and I have heard that this may have something to do with it. These are just things I have heard but have done no research on yet…as I am always cold and my boyfriend never is! It’s always a compromise when going on long car trips without climate control 🙂

    1. I would believe this. When I was younger I was always cold and could hardly get warm enough to sweat. Now that I’m going through “the change” I am hot all the time. My husband calls me “furnace woman”. I used to have the mattress pad heater on, with extra blankets in the winter. Now I am so hot usually just a sheet will do it, and hubby is huddled under the blankets. I love to stand outside in the winter without a jacket and cool down.

    2. Well, one reason women feel colder then men is because they ARE. During the first part of the menstrual cycle, estrogen comes out to play, and your temperature is lower. When an egg is ready to be released, your temp takes another small dip, because a high body temp could damage an egg. Then progesterone comes out to play (which is what a fertilized egg needs to attach) and your temp rises in response. All women who are menstruating normally go thru this bi-phase shift in temps, every single cycle. As you age and your estrogen lowers (menopause) you will warm up and get hot flashes and such. As our hormones fluctuate, so does our body temp 🙂

  21. Right now, it is HOT where I am, but I have plans to try harder to really experience winter this year. But I have to experience summer first.

  22. Howard, I was under the assumption that the world’s temperature has varied often during our specie’s evolution?

    Also, would anyone in the field of metabolic disorders like to weigh in on Kiki’s dilemma?

  23. Here’s an anecdote: we had a guy visiting from Arizona for a year. He decided to swim in the lake (Lake Geneva) every single day, ALL YEAR LONG. He got skinnier and skinnier as the year went by. I think he used a wetsuit in the winter. By the end I think his body fat must have been in the single digits.

    I can’t stand going into cold water or I’d try it out. However, I do blast cold water for about 30 seconds at the end of my showers. It makes getting out so pleasant.

  24. Okay, but what about getting cold from the inside out? I live in Texas and between the seemingly incessant heat and my intermittent anemia I eat A LOT of ice. The ice eating keeps me very cold even when it is 100+ degrees out and I’m out on the porch soaking up the sunshine. Everyday i eat a lot of ice which gets me very cold but I also drink a big pot of elderberry green/oolong tea and that gets my furnace burning so I am getting both extremes in there. But ever since I started eating so much ice I have noticed that despite running, pilates and yoga I seem to be unable to shed those last few pounds around the waist. I usually lose weight in the summer but this year I have not been able to get back down to my “summer weight” and I had actually started to think that the ice was making me retain body fat–as in, maybe I had tricked my body into thinking I live in Alaska and have to keep that fat on all year. Anyone have any thoughts on this?

    1. I’m in Texas also. I lived I. Korea during winter and gained the most weight ever had then, despite calorie restriction (plus rice carbs I’m sensitive too). I had to work in the cold etc, and same when I flew in Texas during winter often heater didn’t work, again I gained despite it all. While I might can get to a level of comfort in cool air etc, I crave being warm. Warm climate population (before modern ac etc) often were less advanced than more moderate climate population. For some heat makes people lazy, but for me I can function. I may have just a touch of brown fat, but too much cold that even includes the ac in the house just makes me uncomfortable, an hour in the warmth of the sun plus that vitamin d I’m ready to take on the day into the night!

    2. Hey, why don’t you get an iron transfusion instead of staying anemic?? I have always battled anemia but never could imagine purposely eating ice…until one time I found myself going from fast food place to fast food place asking for cups of their tiny ice cubes/flakes/circles. I then found out that my iron was very low (didn’t realize ice eating was a symptom) and had several weeks worth of iron transfusions. I felt CONSIDERABLY better. (I don’t absorb supplements very well)

  25. In warm weather, swimming in a nice cool pool is the bomb. Meaning, you get goosebumps and it’s hard to walk in, so you resort to the big jump, but once you’re in you’re happy swimming and splashing around. I’m in for hours tho, not minutes, when I can do it.

  26. I work outside all year round, and have no central heating. I have recently started experimenting with the cold packs on the belly for half an hour a few times a week. Since then I have noticed the same thing another poster mentioned–getting very warm after eating, especially around the neck, upper back and chest. I used to experience this only after eating coconut oil.

  27. Why not try an ice pack on the back of the neck and shoulders as well?

  28. My 7-year-old daughter has always been thin (sinewy, not skinny-fat), eats a ton and never wears more than a t-shirt even in the winter. When the docs fixed her heart years ago, I said they set her “idle” too high. Maybe she just has a lot of brown fat!

    I just read an article in the Washington Post about heat adaptation (the body’s process for acclimating to summer heat). It said that our bodies burn more fat in hot temperatures as part of the cooling-off process. Anyone hear of that?

  29. Interesting. California beaches are right around 55-63 degrees.

    Time to hit the surf after work more often

  30. Yes! For years I’ve advised people to stop avoiding every inkling of temperature extreme as warming you up or cooling you down revs metabolism. Nothing is more annoying than watching overweight people pre-heat their cars with automatic starters every cold winter morning. Same goes for all the women that refuse to go in or stay in the water at beach or pools…

  31. Mark, you know what is funny? They usually label you like accessible…But as a medical student, I have to say you are very well informed, and the ability to communicate extensive research in such a simple and appealing way shouldn’t hide the fact that you truly understand the topic! I usually try to re-check everything, but you do it for me. Thanks for Your books and articles.

  32. What about people who live in chronically hot places? Like Florida? Does cooling the body also burn calories?

  33. I’m not sure if it was intentional but I find it funny that in the picture that shows the definition of fat, it has corpulent, pudgy and also profitable, rich. The government that influences the health authorities which recommend high carb diets is making America corpulent and pudgy while making them rich.

  34. I feel far more energized in cold weather than I do in hot weather. Hot, humid temperatures make me tired and aggravated.

    1. Great job on your blog! Have you considered eating “primally” while continuing to bodybuild? Also, you documented your weight and body fat stat…one question that came to mind is “What is your height?”

  35. This was covered in the 4 hour body. Was very interesting reading. I know take cooler showers although I HATE being cold which is a very standard condition for me since I’ve lost weight.

  36. It’s rather unpleasant to adapt to cold water, but the feeling when you leave the shower after “cold session” is great.

  37. Hmm … I get cold and tired after eating, to the point where I need to go wrap up in bed after anything more than 10 bites of food. I can’t seem to regulate my body temp at all anymore, I’ve seen doctors about it. I tried the HCG shots last summer just to see if I could burn off the “right” kind of fat; they were thinking I didn’t have enough of the keeps-you-warm-around-the-organs kind. I eat very little and am very overweight anyway. I wonder if it’s anything to do with my fat type ratio, and if so, how would I go about fixing it? I am already cold all the time so whatever brown fat I have must be worn out.

    1. Hmm, sounds like me after eating rice 2 days running. I think I’m very allergic to the stuff. Good thing it’s now a rare item of diet. Ever think of trying an Elimination Diet? Results might shock you
      no end.

  38. 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?!

  39. 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.

  40. 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.

  41. 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!

  42. 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.

  43. 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.

  44. maybe we should alternate cold and hot showers. any advantages to hot showers, other than the enjoyment?

  45. 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.

  46. 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.

  47. 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.

  48. 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!

  49. 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!

  50. 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!

  51. 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.

  52. 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?

    1. 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.

  53. 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!

  54. 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!

  55. 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!

  56. 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.

  57. Brown Adipose Tissue doesn’t sound very appealing… maybe we need a mascot?

    I’m thinking….. BATman 😀

  58. 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.

  59. 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.

    1. 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.

  60. 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!

  61. 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.

  62. 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.

  63. 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!

  64. 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…

  65. I have been doing vasper http://www.vasper.com 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…..

  66. 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 !

  67. 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!

  68. 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.

  69. 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.

  70. 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?!

  71. If you look at the birth of naturopathic medicine, it originated in Europe. They were using cold water to treat all types of diseases back then. Stimulate the immune system via cold baths and walking for miles was a common protocol.

    Those who couldn’t withstand the cold were thought to have worse prognosis.

    Mason ND student

  72. This is an important piece to keeping weight off. Brown fat, when activated, burns triglycerides and glucose, as well as fat. The more brown fat you can coax your body to make and activate, the higher your metabolism will be.

    However, brown fat uses up many nutrients, particularly iron. People who are iron deficient, and when the body needs more iron and it’s not available brown fat will be compromised.
    It’s very important to make sure that a high nutrient diet is being consumed (as well as able to be absorbed) so that adequate iron (as well as copper, B-vitamins to run the mitochondria, selenium) is available, or the cold exposure will only tax the body.