S.

There's a multibillion dollar industry dedicated to convincing you to spend a bunch of money to get rid of facts.

But fat isn't an enemy.

We spend so much time and money trying to eliminate it that we never give that a proper chance to amaze us.

Our fat is an evolutionary advantage, allowing us to store a lot of energy and relatively dense packages like we talked about in the last episode, Gram for Gram.

That is the most efficient way to store energy in our bodies.

And it's not just a storage center.

It's an ever changing organ that contributes to our well being.

In today's episode, we'll learn about what are fat does and hopefully walk away a little more excited that it exists as a quick disclaimer.

We're not talking about dietary fats like the one from oil, butter or meets.

This video focuses on fat as adipose tissue, a collection of different cells that we have in different locations in our bodies.

This type of tissue is made of Endo Feel sells a few immune cells, but mostly a special type of cell called Ad Oppa sites in every gram of adipose tissue you'll find anywhere from 1 to 2 million, Adam recites.

Here's what I think.

It's so cool that sells aren't passive structures out of the site has site in the name, so we know that it's a living, metabolizing cell, and if we zoom in on it, we can see cell structures like a nucleus with DNA in it.

But most of its body is a storage site for lipid the energy storage were so interested in.

We have about 30 billion fat cells, and when we store some excess energy, the cells will grow in size.

Then if they can't grow anymore, but you still need to store energy, you'll grow new fat cells so you can store more energy.

Now, when we see pictures of body fat, it's usually shown is a lumpy yellow tissue, and it's true that is a type of fat that exists.

But that's not the only type of that we have.

The type of fat you're used to seeing is probably visceral.

Fat.

Visceral just means that it's in the abdomen surrounding your internal organs.

This is what's often called belly fats, although there's a little more to it than that.

We have another layer of fat underneath our skin called subcutaneous facts sub for under cutaneous for skin.

If you have skin, this stuff is under it.

That means the scan under but chest thighs.

And yep, the abdomen subcutaneous that is used mostly for energy storage and some, but not a ton of insulation.

We keep that in a few other sneaky spots, too.

Some fat has mawr of a mechanical purpose, like the fat that supports the eyes and the fat pads that cushion the heels.

And we have that between some of our skeletal muscle fibers.

It doesn't matter if you have a lot of body fat or if you're very lean.

Everyone has fat in their muscles.

In fact, you can see intra muscular fat as the marble and a cut of steak, along with the visceral and subcutaneous that these locations of fat make up your white adipose tissue that add up a site we showed you earlier was an example of white at opposed issue, but you also have a separate type called brown adipose tissue, which mostly exists so we can create body heat.

It cell looks a little different.

Check out how it has multiple lipid droplets compared to white out oppa sites, but it's also got quite a few more mitochondria, and it's surrounded by blood vessels and nerves so it can heat up the blood brown.

That is especially useful when you're a baby.

Newborns can't shiver for warmth, so they rely on brown fat to stay toasty.

Babies are useless as you get older, though you develop other strategies to stay warm, like shivering or just putting on a hoody.

This brown adipose tissue was more useful for our ancestors who were exposed to the elements.

Plus, this tissue is only found in mammals, so other animals use it to help them keep warm, too.

Although there are some circumstances where we will use it as adults like before, knocked out during general anesthesia, and our bodies detect low body temperature, you're definitely not putting on a hoody, then, on account of, you know, being knocked out and everything now, for a long time, people thought that was a passive energy storage reservoir.

It was a useful source of emergency calories, but otherwise it didn't serve any larger function.

These days we know that's not true, especially when we consider its role in the endocrine system.

This is a system that handles hormones, including the sex hormones like estrogen and testosterone, but also other hormones that have effects on parts of the body that aren't that.

Before scientists name any of the specific hormones they suspected, there might be something floating around the blood that signaled energy levels to the central nervous system.

One of the first big moments in this concept was back in the early seventies.

Within an experiment on obese and diabetic mice.

See, scientists can breed mice with different genetic profiles or Gina types that results in predictably physically different mice or FINA types of mice.

In this case, a tweak in the O.

B.

Gene.

Part of the mouse's genotype results in an obese mouse.

It's Phoenix hype.

This makes sure that the test subjects are as consistent as possible.

During the experiment, mice were stitched together in an experimental condition called Pera Bio sis, meaning certain aspects of their anatomy, including their circulatory systems, were connected.

This style of experiment used to be more common in the sixties and seventies, and it led to some big breakthroughs in our understanding of hormones and in the immune system.

The experimenters at the time set up four para biotic scenarios, and obese mouse joins to a normal, healthy mouse.

A diabetic mouse joins to an obese mouse, no beast with an obese and finally normal with normal as controls.

It was common for some of the mice to die during the experiment, and in the diabetic obese combo.

The obese mouse tended to get hyperglycemia and die.

But most of the mice in the other condition survived, meaning almost all of the obese, obese combinations made.

Its and both partners gained weight quickly.

On the other hand, the obese normal combinations also survived and gained weight, but to a lesser degree than the obese, obese mice, the researchers.

That meant that the normal mice were secreting some kind of hormone that regulates food consumption into the bloodstream of their obese partner.

Now every hormone needs a receptor, and this hormones main source of receptors was in the hypothalamus, a portion of the brain that signals the release of a bunch of other hormones to now.

Here's the big payoff that para biotic mouse study gay researchers, a substance to look for what they called a satiety factor that O.

B.

Gene that resulted in obese mice had also been shown to make a specific protein.

And in 1994 that hormone was discovered and named left in its a hormone released from Adipose sites.

That tells our bodies we have enough energy and we're not starving.

Out of the sites will give off different amounts of lepton, depending on how much fat mass we have.

Our nutritional status, plus a few other factors left Inn's main job is to signal that you have enough energy stores, not excess energy stores.

So when you don't eat enough or you're losing weight, lowered leptin levels are a signal to your brain that it should eat more.

That's one of the reasons that diets are largely pointless.

Your body will literally adjust to tell you to eat more.

Left in is involved in a few other things, too, like immune function regulation and bone development.

And lepton isn't the only hormone that fat tissue makes.

It also makes a hormone that helps regulate blood sugar called at a connection, and a bunch of enzymes that can modify steroid hormones like estrogen and testosterone.

that's especially useful if you're a person with ovaries.

End in menopause.

Up to 100% of circulating estrogen comes from adipose tissue for postmenopausal women, as if the energy storage and hormone production wasn't enough, fat is also a useful source for stem cells.

Stem cells can become other types of cells and show promises treatments in the future.

And in the last few years, scientists around the world have figured out ways to take that tissue and turn them into stem cells.

This is called induced pluripotent.

See, we take a mature cell and transform it into a cell that can become other cell types.

That's great, since we have plenty of adipose tissue on our bodies, and it's easily accessible with a little bit of liposuction.

This also make sure that stem cells are compatible with the recipients immune system, since they came from the recipient's body in the first place.

But this is all relatively new science, and there's ongoing research to figure out best practices for fat derived themselves.

Plus, there's still more to learn about that's role in the endocrine system to my goal with this episode was to show you that fat is incredibly valuable to our body's fat is part of what makes us human, and it's worth celebrating.

How cool this organise.

Thanks for watching this episode of seeker human and depreciating the body with us.

I'm Patrick Kelly.