What Is Brown Fat? Why It's Good & How to Get It | Dr. Susanna Søberg & Dr. Andrew Huberman
00:00:00.000 | Let's talk about brown fat.
00:00:05.440 | If you're willing, I'd love to drill into brown fat at a deep level.
00:00:10.320 | Again, my understanding of this is far more elementary than yours, obviously.
00:00:16.040 | You're the expert.
00:00:17.200 | My understanding about brown fat is that it's located in specific areas of our body, maybe
00:00:24.160 | more widespread than when I learned in school.
00:00:26.920 | I was taught it was just at the clavicles and the back of the neck and upper back, but
00:00:30.560 | who knows?
00:00:31.560 | I learned that there's more of it when we're children, maybe more distributed throughout
00:00:34.960 | our body, and that it's rich in mitochondria.
00:00:39.480 | What is so special about the brown fat?
00:00:41.760 | If we could just go into the biology of brown fat a little bit, what does it look like?
00:00:46.360 | You've measured it in human subjects.
00:00:48.920 | Where is it distributed really?
00:00:50.880 | Can it expand its distribution?
00:00:52.920 | Can we activate and expand the amount of brown fat as adults?
00:00:58.720 | For those of you that are cringing already thinking we're talking about getting fatter,
00:01:02.100 | it's quite the opposite.
00:01:03.100 | We're talking about not subcutaneous fat, but fat located around the organs.
00:01:07.740 | Please educate me.
00:01:09.380 | Tell me where I'm wrong and expand my knowledge on brown fat.
00:01:13.240 | Okay.
00:01:14.240 | Yeah, you are not wrong, but it's true that there are more locations of the brown fat
00:01:21.400 | than we previously thought.
00:01:23.680 | There's this very nice study from 2017 by Leitner et al., where they had made these
00:01:29.960 | PET-CT overlays of their subjects, but you can see where in the body do we have brown
00:01:37.080 | fat and where can we grow more brown fat, so to say.
00:01:42.380 | So the brown fat is very plastic, so it means that it can grow and it can decrease, and
00:01:47.800 | this is proven in studies where we have seen people with a failed cryocytoma, it's like
00:01:55.040 | a very specific cancer type, where from the '70s where we can see that if they have this
00:02:02.240 | specific kind of cancer type, they have this tumor on the adrenal gland, so they have like
00:02:09.760 | a huge increase in noradrenaline.
00:02:12.560 | And because of that, they have this continuous activation of the brown fat.
00:02:17.120 | And they have grown a lot of brown fat in the whole body, abdomen, or where it's located
00:02:22.600 | in these six different places, but it is very much compared to normal people.
00:02:29.520 | And what they then see, what we learned from this study, is that brown fat can apparently
00:02:34.760 | grow if you have an increase in noradrenaline in the body.
00:02:39.440 | It's not like you want that, because when that happens, you have a high blood pressure.
00:02:42.880 | You don't want it chronically, right?
00:02:44.400 | You just want it on a short amount of time, and then it can grow for a bit, but you don't
00:02:49.040 | want it chronically, of course not, because it activates also your sympathetic nervous
00:02:53.960 | system.
00:02:54.960 | So they have also showed they have high blood pressure.
00:02:57.280 | They lost a lot of weight, of course, because this is activating your metabolism.
00:03:02.760 | So they found, luckily, that when they removed this benign tumor, that the brown fat decreases
00:03:12.800 | again to normal size, and they gained weight again, and they had normal blood pressure.
00:03:17.520 | So the story ends well, but it's kind of like proof of concept of the brown fat can actually
00:03:22.440 | grow.
00:03:23.440 | So it's plastic in its way of like it can grow and it can decrease again.
00:03:27.920 | So that's very good, good studies to see what the body is capable of.
00:03:33.640 | But we don't, of course, want all that brown fat.
00:03:35.880 | We just want it to be, we just want to keep it, actually, and keep it activated, because
00:03:41.000 | what we see in studies is also that after the age of 40, people, studies have shown
00:03:48.080 | that there is an association with having less brown fat, but increased obesity.
00:03:52.720 | So of course, we don't know yet whether brown fat decreases with age, and therefore we get
00:03:59.040 | obese or we get obese, and therefore we have less brown fat.
00:04:03.120 | But as brown fat is an insulin sensitive organ in our body, and we get obese, just like the
00:04:11.880 | muscles get less sensitive, insulin sensitive, the brown fat does as well, and therefore
00:04:17.920 | it maybe decreases.
00:04:19.360 | It could be a theory that I think could be one of the reasons why we don't see that much
00:04:25.360 | brown fat in elderly people.
00:04:28.120 | Some have a lot, especially people working outside, there are studies showing this.
00:04:32.840 | People who do physical work outside, farmers, and interesting.
00:04:37.680 | Yeah.
00:04:38.680 | They expose themselves to it, so they'll just keep it in that way.
00:04:44.840 | And I suppose we should clarify for people in case they don't know that insulin sensitivity
00:04:51.280 | is a very good thing.
00:04:52.480 | You want that.
00:04:53.480 | You want your cells to be sensitive to insulin.
00:04:55.440 | Insulin insensitivity is type two diabetes, and is associated with obesity.
00:05:01.040 | So just a point of clarification there.
00:05:03.920 | Yeah.
00:05:04.920 | It's interesting to me.
00:05:05.920 | I usually work out at home, but I go to a gym once or twice a week if I can, because
00:05:11.120 | it's good if I see the outside world.
00:05:14.640 | And there are a few individuals at the gym who, they're not particularly large or muscular,
00:05:21.960 | but they are incredibly lean, and their posture is great, presumably from the musculoskeletal
00:05:29.040 | work, and they're in their 70s and 80s.
00:05:34.040 | I mean, it's remarkable, right?
00:05:36.600 | And I know all the telltale signs of hormone augmentation.
00:05:39.160 | I'm very good at spotting that.
00:05:40.320 | There are a few telltale signs.
00:05:41.320 | I've talked about this on other podcasts, and that's not why they're fit.
00:05:48.240 | They're clearly of that look, and you see this outside the gym too, of course, for people
00:05:52.280 | that look like they've done a lot of physical labor their whole life.
00:05:56.360 | They're just moving a lot.
00:05:57.960 | They have strong hands and features, and they're not necessarily excessively lean, but you
00:06:05.160 | can tell that they've been using their musculoskeletal system.
00:06:08.900 | And I like to talk to these people and ask them, not what are you doing now for your
00:06:12.520 | workout, but what did you grow up doing?
00:06:15.600 | And I would say, and obviously I haven't run statistics on this, but more than 75% of them
00:06:21.680 | respond that they grew up on a farm or that they did some sort of manual labor or were
00:06:28.440 | a postman or a postwoman or doing something where they moved a lot for their early years
00:06:33.320 | and throughout middle age.
00:06:35.520 | And most of them are now in retirement, but some of them are still working and they all
00:06:39.360 | still moving a lot.
00:06:41.320 | So the relationship between shiver and brown fat makes sense to me, but is it the case
00:06:47.480 | that as we're just moving around, I've heard of NEAT, non-exercise induced thermogenesis.
00:06:52.760 | So if we're just moving around, that we are activating brown fat, or does there need to
00:06:57.680 | be this stressor?
00:06:58.840 | Does there need to be shiver and a cold stimulus or a heat stimulus to activate the brown fat?
00:07:03.840 | In other words, is just staying active enough, or do we need to do some sort of temperature
00:07:10.400 | shock type thing like deliberate cold exposure?
00:07:13.480 | Yeah, I think that is a really good question, because how, also why do we have this tissue?
00:07:19.680 | Then if it has to be extreme, then you can question what do we need this tissue for?
00:07:24.960 | But it seems that you can activate the brown fat with just a little bit of exposure to
00:07:28.840 | cold.
00:07:29.840 | So cold is the most potent stressor activator of our brown fat because it's our temperature
00:07:35.760 | regulating organ in our body, so first responder to that.
00:07:39.200 | So the muscles will be a little bit too late, and therefore we have maybe these two kind
00:07:43.760 | of tissues.
00:07:44.760 | So actually just exposing yourself or a hand actually just to cold water.
00:07:49.880 | So studies have shown that if you just put your hand in cold water, not that you're going
00:07:55.480 | to do that all day or every day or anything, it's not something you have to do, but it
00:08:01.440 | just shows that you can activate your brown fat just by getting a temperature change on
00:08:06.560 | your skin.
00:08:07.560 | So you can go outside in a t-shirt, that's why also we were just talking about, well,
00:08:11.240 | people who works outside or move a lot or get in and out of it, like changing the temperature
00:08:17.040 | of their body all the time, they will have more brown fat and activating that is going
00:08:22.960 | to keep your metabolism higher and your insulin sensitivity, studies have also shown this.
00:08:28.080 | So the brown fat can be activated as soon as you just change your temperature in the
00:08:32.440 | skin.
00:08:33.440 | So going outside in a t-shirt, wearing cooling vests, also studies have shown this for 10
00:08:37.320 | minutes, it's going to also grow your brown fat.
00:08:41.040 | So you can get more brown fat if you expose yourself to the cold.
00:08:45.340 | You don't have to start in a cold shower.
00:08:48.120 | You don't have to start in a cold plunge if you're not really ready for that yet.
00:08:52.900 | But just exposing yourself to the cold wind has also shown to activate your brown fat.
00:08:58.400 | Or if you don't want to be like in this awake state, then you can also just sleep in the
00:09:04.440 | cold and you won't notice it that much, maybe, but studies have shown that if you sleep in
00:09:08.800 | 19 degrees Celsius, then you will activate your brown fat and you will grow your brown
00:09:15.560 | fat.
00:09:16.560 | So you have more of it.
00:09:17.560 | So this very nice studies from Hanson et al. from 2017 showed that a group of subjects
00:09:27.000 | who slept in a room at 24 degrees, and then they made this PET CT scanning to see how
00:09:32.560 | much brown fat do they have from the beginning, so what we call baseline.
00:09:36.640 | Then they measured again after a month of sleeping in 19 degrees and they saw, I think
00:09:42.360 | it's remarkable, just one month at 19 degrees sleeping there.
00:09:45.440 | They had a duvet on and they were still had clothes on when they're sleeping.
00:09:50.760 | So they're under a cover, under a duvet.
00:09:52.680 | Under a duvet, yeah.
00:09:54.120 | The subjects were sleeping at 19 degrees for one month, had increased insulin sensitivity.
00:09:58.700 | The next month they slept at 24 degrees, they measured this again and they had decreased
00:10:03.740 | actually a little bit, and then they slept at 27 degrees.
00:10:07.040 | So quite warm room actually for the fourth month and they saw even less activation of
00:10:14.240 | the brown fat and also insulin sensitivity.
00:10:16.640 | So it seems that you can expose yourself and pretty rapidly the brown fat will respond
00:10:22.720 | to this because it's so sensitive to noradrenaline, right?
00:10:26.740 | So if you keep exposing yourself to a little bit of cold, you also get a little bit adapted
00:10:31.920 | to it, but that's because the brown fat has grown these more mitochondria in the cells.
00:10:37.640 | So these small energy fabrics, that's going to activate the cells and that's going to
00:10:41.360 | take up glucose and fat from the fatty acids from the bloodstream to keep the thermogenesis
00:10:48.260 | up.
00:10:49.320 | And that's going to clear up some sugar and it's going to clear up in the bloodstream
00:10:54.020 | and some fat as well.
00:10:55.400 | So the brown fat can in that way decrease our unhealthy fat, which is the white fat.
00:11:02.120 | And the white fat is what we don't want too much of, but we still need some, of course,
00:11:07.960 | and it's our energy storage.
00:11:09.320 | So it's very important that it's there.
00:11:11.000 | We just don't need a lot of it.
00:11:12.960 | So on our thighs and also around our inner organs, that's where it's located.
00:11:18.040 | So if we can have activation of the brown fat just by going out in the cold and just
00:11:22.800 | by sleeping in a cold room, or if you have courage for it, you can go out and expose
00:11:27.080 | yourself in a cold plunge.
00:11:29.600 | Cold showers is also going to do the trick.
00:11:31.960 | So you can do different variations of this.
00:11:35.060 | Just exposing yourself to various temperatures is going to activate the brown fat because
00:11:39.560 | it was involved to keep us in a perfect homeostatic balance regarding temperature.
00:11:45.360 | So to keep us alive.