Brown Fat – Your Body’s Attic Insulation

BAT-Activation (brown fat activation) has some amazing benefits including fighting obesity, long life, and better circulation, it can:

  • protect from atherosclerosis (plaque in arteries)
  • improves insulin sensitivity (of interest to type 2 diabetes sufferers)
  • may improve bone health
  • increases adiponectin (longevity hormone)
  • upregulates FGF21 (improves insulin sensitivity and glucose metabolism)
  • increases circulating irisin (involved in the building of lean muscle mass, convert white fat to brown fat)
  • increases SIRT1 (increases BAT activity)

Many animals in nature prepare for winter through fat deposits, particularly brown fat (BAT) activation, we are vastly different to animals in many ways, but there are similarities in terms of our hormonal response to certain foods and our ability to activate brown fat through insulin raising foods (a recent discovery) and acute cold.

Animals do not choose to get fat for winter, the environment changes for them and instincts do the rest.  They evolved to work in balance with the seasons over the course of thousands of years.  For example grizzly bears eat acorns in the autumn time, which have a very interesting nutrient ratio of high carb and fat with moderate protein (similar to human baby milk and junk food).  A couple of years ago squirrels got fatter than normal in autumn because it was mild and their autumn food supply was accessible for a lot longer, they didn’t choose to get fatter, the environment changed.

Humans on the other hand are educated somewhat about nutrition (incorrectly to a large degree because of poor science), yet we succumb to instincts as we often overeat foods that taste nice.  The very reason they taste nice is because they push our primal buttons.  Our environment has changed drastically in the past 100 years and food is no longer seasonal as we have every single type of food available all year round. The foods that really taste nice to us are autumnal:  potatoes, corn, wheat, fruit and all the derivatives such as cakes, fries, chips, crisps, breads, breakfast cereals, chocolate, pasta, pastries and so on.  You can now eat these foods in march, yet in nature there would be no way for a stone age person to have such foods at that time of year.  Our instincts are driven crazy just like animals in autumn as a result, and unfortunately for us, we now live in an eternal autumn and the seasons never change, from a food point of view. The result is chronic weight gain, which is now prevalent.  Simple common sense really.

So what would happen to someone that existed 10,000 years ago in a country where there were pronounced seasons?  Vast areas of the world have more extreme seasons and the further away from the equator you went. Less sugar and starch would exist in these areas as it takes the sun’s energy to really create high gi foods.

(Interestingly type 1 diabetes is more prevalent the further you go from the equator and is on the increase, is it that people evolved and adapted to function with less sugar/starch and thus became more sensitive to it, and nowadays because the environment has changed so much, human bodies simply cannot cope with it and malfunction?  I think it’s very likely!)

Essentially our diets would have changed drastically between spring summer autumn and winter:

  • Spring would have had young animals and fish for us to hunt, and some forms of veg beginning to grow.  This is a very low GI season, and we would have had plenty of protein in proportion to fat and carbs.
  • Summer would have had plenty of berries, from raspberries in early summer, to blueberries, blackberries and strawberries etc. along with the staples mentioned in spring. Now with some sugar introduced and protein, this would have made us strong and given us more energy for the hunt and activity during the warm summer months.
  • Autumn would have had all of the rest of the harvest all sorts of fruit and grains and more root veg too, a fantastic time of year.  This is the hyper-carb season and would have sent our blood sugars crazy and along with the staples and nuts appearing it would have made us plump, like squirrels, to prepare us for winter and given us energy from sugars to allow us to collect lots of nuts for winter.
  • Finally winter, from experience we would have learned about the cold and the lack of food available as leaves fell of trees and fruit, grains etc decayed. We would have collected lots of nuts which would have given us energy over the winter.  This period may have put people into a ketogenic state as opposed to utilising glucose for brain and nervous system i.e. total fat burners, instead of just using fat aerobically.  Then we would have moved into spring having lost all of the winter weight.

Of course there were other sources of food, like low gi veg dictated by the seasons which would have had beneficial nutrients and fibre, but would have had little effect on our body-weight.

So what is happening from a hormonal point of view?

Here are a few hormones involved based on my understanding of the research…

  • Leptin: This hormone is a hunger limiter, it’s level increases as we gain body fat and is secreted from our white fat cells.  It essentially tells the brain how much bodyfat we have.
  • Ghrelin: This is the hunger hormone, secreted primarily in the stomach, and has a different response based on amount of food in the stomach and the type of food eaten.
  • Dopamine: This is released in our brains when we eat sugary foods, a comfort fix and reward sensation, which may lead to gorging and sugar addiction.
  • Insulin: This is secreted by the pancreas when our blood sugar levels rise to drive them back down to normal levels, or from eating protein.
  • Glucagon: This is secreted by the pancreas when our blood sugar levels are too low to draw sugar from the liver, or when an amino acid found in meat, for example, known as arginine is digested.

Still with me? Great!

So the really interesting thing is this, and I believe backs up the Don’t Eat for Winter hypothesis very well:

In autumn, insulin levels are high and dopamine response would have caused a a gorge season.  Carbs cause a pronouced ghrelin drop and bounce back, which meant we’d be delighted with what we ate, but hungry more quickly after eating and so we’d gorge again and get another fix.  We would have savoured our food and ate and ate, keeping insulin spiked and our bodies in a continuous fat storage mode.

When sugar/starch raises insulin, and leptin levels are high (from bodyfat), our bodies create a layer of brown fat around our neck shoulders and chest.  This situation could have happened in Autumn time for our stone age ancestors. Brown fat is an excellent insulator and only recently has it been discovered that adults can actually form new brown fat in these areas.  It is also an energy burner drawing energy from white fat cells, so for me it seems like it is like an internal scarf/hot water bottle protecting us from the cold.

One other thing that stimulates the genesis of this brown fat is acute cold. Winter anyone?  So between carbs and cold, ie. the transition from autumn foods to cold of winter, it seems we activate our brown fat scarf (BAT-scarf) to keep us warm and hardy over the winter.  With a stone age haircut the insulation is even more effective. Remember heat rises and so having this layer on the top of our upright bodies is the ultimate place to have such an insulation layer.  Brown fat is your body’s attic insulation!

You can read more about brown fat (BAT), known as the hibernating gland, on wikipedia and it’s insulation, heat generation benefits and how it’s activation has other amazing health benefits for us and longevity in animals.

A summary of health benefits for humans include:

  • protect from atherosclerosis (plaque in arteries)
  • improves insulin sensitivity (of interest to type 2 diabetes sufferers)
  • may improve bone health#
  •  increases adiponectin (longevity hormone)
  • upregulates FGF21 (improves insulin sensitivity and glucose metabolism)
  • increases circulating irisin (involved in the building of lean muscle mass, convert white fat to brown fat)
  • increases SIRT1 (increases BAT activity)

All of these seem to assist with metabolism and longevity and should not be underestimated in terms of their health benefit.

In terms of benefits to animals, this is pretty amazing, animals that have BAT live longer when exposed to more cold, maybe it’s the same for us too if we can develop more BAT:

“The longest-lived small mammals: grey squirrels (24 yrs), bats (30 yrs), and naked mole rats (32 yrs), all have remarkably high levels of BAT and BAT activity. Furthermore, in animal species that span a wide range of latitudes, the within-species longevity is correlated with how far north (or south, in the southern hemisphere) an individual lives suggesting that cooler environments lead to increased BAT activation and increased lifespan across a wide range of species.”

Come winter, and we begin eating nuts, insulin drops and we become ketogenic, this means we are now in full fat burning mode, using fat reserves and the fat in nuts to keep us burning fat like a furnace.  Research shows us that in this state we burn up to 300 more calories a day.  We become hotter and we keep fueling our brown fatty scarf to keep us insulated and warm during winter (obviously furs and hides would have kept us warm along with our dignity intact during this season).

In spring then our diets would return to meat and insulin levels raised but ghrelin levels more stable and less dopamine response so our food would have been more satiating and we’d go back to having more balanced blood sugar levels and less hungry.  The glucagon response from the arginine in the meat would have prevented us storing any more fat than necessary and kept our blood sugar levels from dropping too low, keeping our minds sharp.

Summer then would have us with a little more insulin flowing about keeping us more anabolic along with the meat and giving us energy for hunting and keeping us alert to danger and building muscle.

In today’s world we live in an infinite autumn priming our gorge instincts, switching fat storage more on all of the time and our hormones have gone haywire.  Is it any wonder we are in an absolute crisis when it comes to obesity. The thing is it’s not a person’s fault for being fat, no more than those fat squirrels in autumn a few years ago.  We cannot fight instinct with will power and calorie restriction when we are pushing primal buttons, that’s pure punishment. You can use your intellect to not allow instincts to be triggered and thus control you and realise that not all calories are equal, not by a long shot.  We’re not furnaces, we’re hormonal creatures that use food for energy, construction, and body processes that support our continued survival. Amazing!

We can have dominion over our bodies but it takes a bit of awareness about the processes going on and the wisdom to implement change based on that knowledge.

That’s it in a nutshell really (pardon the pun).

For more information check out my book ‘Don’t Eat for Winter‘ to discover how to work with our modern environment and control our autumnal urges, gorges and fat storage processes and get back to healthy body fat levels.

Now, time for a cold shower and some starch to increase my BAT activation.

This winter I’m gonna be BAT-man!

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Author of Don't Eat for Winter. 2 time European, pan-American and World amateur kettlebell champion. who went from an obese 115kg to a fit and healthy 78kg through his 5 year journey of discovery around nutrition and exercise. I believe that we will see an avalanche of fat fall from the Earth as people escape from the infinite autumn through The DEFoW Diet concept.