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  #1   ^
Old Thu, Jun-27-19, 02:56
Demi's Avatar
Demi Demi is offline
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Plan: LCHF/IF
Stats: 217/000/160 Female 5'10"
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Default What made humans 'the fat primate'?

Quote:
Science Daily
June 26, 2019

What made humans 'the fat primate'?

Changes in DNA packaging curbed our body's ability to turn 'bad' fat into 'good' fat


Blame junk food or a lack of exercise. But long before the modern obesity epidemic, evolution made us fat too.

"We're the fat primates," said Devi Swain-Lenz, a postdoctoral associate in biology at Duke University.

The fact that humans are chubbier than chimpanzees isn't news to scientists. But new evidence could help explain how we got that way.

Despite having nearly identical DNA sequences, chimps and early humans underwent critical shifts in how DNA is packaged inside their fat cells, Swain-Lenz and her Duke colleagues have found. As a result, the researchers say, this decreased the human body's ability to turn "bad" calorie-storing fat into the "good" calorie-burning kind.

The results were published June 24 in the journal Genome Biology and Evolution.

Compared to our closest animal relatives, even people with six-pack abs and rippling arms have considerable fat reserves, researchers say. While other primates have less than 9% body fat, a healthy range for humans is anywhere from 14% to 31%.

To understand how humans became the fat primate, a team led by Swain-Lenz and Duke biologist Greg Wray compared fat samples from humans, chimps and a more distantly-related monkey species, rhesus macaques.

Using a technique called ATAC-seq, they scanned each species' genome for differences in how their fat cell DNA is packaged.

Normally most of the DNA within a cell is condensed into coils and loops and tightly wound around proteins, such that only certain DNA regions are loosely packed enough to be accessible to the cellular machinery that turns genes on and off.

The researchers identified roughly 780 DNA regions that were accessible in chimps and macaques, but had become more bunched up in humans.

Examining these regions in detail, the team also noticed a recurring snippet of DNA that helps convert fat from one cell type to another.

Not all fat is created equal, Swain-Lenz explained. Most fat is made up of calorie-storing white fat. It's what makes up the marbling in a steak and builds up around our waistlines. Specialized fat cells called beige and brown fat, on the other hand, can burn calories rather than store them to generate heat and keep us warm.

One of the reasons we're so fat, the research suggests, is because the regions of the genome that help turn white fat to brown were essentially locked up -- tucked away and closed for business -- in humans but not in chimps.

"We've lost some of the ability to shunt fat cells toward beige or brown fat, and we're stuck down the white fat pathway," Swain-Lenz said. It's still possible to activate the body's limited brown fat by doing things like exposing people to cold temperatures, she explained, "but we need to work for it."

Humans, like chimps, need fat to cushion vital organs, insulate us from the cold, and buffer us from starvation. But early humans may have needed to plump up for another reason, the researchers say -- as an additional source of energy to fuel our growing, hungry brains.

In the six to eight million years since humans and chimps went their separate ways, human brains have roughly tripled in size. Chimpanzee brains haven't budged.

The human brain uses more energy, pound for pound, than any other tissue. Steering fat cells toward calorie-storing white fat rather than calorie-burning brown fat, the thinking goes, would have given our ancestors a survival advantage.

Swain-Lenz said another question she gets a lot is: "Are you going to make me skinny?"

"I wish," she said.

Because of brown fat's calorie-burning abilities, numerous researchers are trying to figure out if boosting our body's ability to convert white fat to beige or brown fat could make it easier to slim down.

Swain-Lenz says the differences they found among primates might one day be used to help patients with obesity -- but we're not there yet.

"Maybe we could figure out a group of genes that we need to turn on or off, but we're still very far from that," Swain-Lenz said. "I don't think that it's as simple as flipping a switch. If it were, we would have figured this out a long time ago," she explained.

Journal Reference:
Devjanee Swain-Lenz, Alejandro Berrio, Alexias Safi, Gregory E Crawford, Gregory A Wray. Comparative analyses of chromatin landscape in white adipose tissue suggest humans may have less beigeing potential than other primates. Genome Biology and Evolution, 2019; DOI: 10.1093/gbe/evz134




https://www.sciencedaily.com/releas...90626160337.htm
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  #2   ^
Old Thu, Jun-27-19, 04:49
WereBear's Avatar
WereBear WereBear is offline
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Plan: Epi-Paleo/IF
Stats: 220/137/150 Female 67
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Default

Interesting side note: I went deeply ketogenic and lost 25 pounds over the first half of the year. I have never been this low, and also, this is the first time I have seen the puckery appearance of excess skin after a loss.

At the time I just shrugged it off. I had done it for health, Iím not a teen any more, I figured it was to be expected. But now, these patches are changing and shrinking themselves.

Which means it wasnít excess skin after all. It was excess body fat, unevenly distributed.

In Carnivore circles, it is held to be that this is the source of the excess skin after weight loss problem. If people were able to lose down to where they should optimally be: they would not have so much of this problem.

After millenia of agriculture, what do we know about how we are supposed to work? With adolescence, my body changed, I got a weight problem, and it was all hormones and carbs, seems to me.

Now I am approaching a body weight that is what I probably should have weighed as a teen.

This is a tribute to Jean (cotonpal) who I think was the one who told me, at the beginning of my low carb journey, that goal weights are only suggestions; that I might be surprised.

Sheís right. I am!
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  #3   ^
Old Thu, Jun-27-19, 07:03
GRB5111's Avatar
GRB5111 GRB5111 is offline
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Plan: Ketogenic (LCHFKD)
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While it's fascinating to compare how different species store fat, it's also fascinating to compare how different species use fat, and that informs us that different storage methods in different species have usually evolved to ensure that species survival under the most typical survival scenarios. Humans use endogenous fat when food is not plentiful. If it were easier to access as an energy source, and if it were accessed before glycogen, it wouldn't be there during the challenging times we really need it. Fast forward to today's conditions where food is plentiful, the interpretation of what is healthy food is backwards, and the processed food available makes obesity and disease possible because humans weren't designed to be healthy in an environment where feeding is constant and "food" choices include metabolic land mines.

Yes, I would answer, there are ways to enable weight loss, but they don't come in a pill or by targeted gene manipulation, they happen when one transitions eating and the stuff eaten for better compatibility with how the human metabolism and related energy use operates. We can do this naturally.
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  #4   ^
Old Thu, Jun-27-19, 08:28
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Bob-a-rama Bob-a-rama is offline
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Plan: Keto (Atkins Induction)
Stats: 230/185/185 Male 5' 11"
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Default

My own personal theory.

Fruit and other sugar/carb crops ripen right before the starvation season. The starvation season in temperate climates is winter and in the tropics the dry season.

Humans who developed a taste for these fattening foods, liked to overeat them, and also could put on fat quickly had enough reserves to get them to survive the starvation season. Those that did not make it, did not get a chance to pass those genes on.

Today's problem is agriculture plus canning, refrigeration, freeze drying, chemical preservation, and fast global freight travel. Those foods are no longer only available right before the starvation season, but are in your grocery store all year long.

In January a person in Washington State can go to Safeway and get a ripe apple. That person can get them in July before the local ones ripen too. They are in the store 365 days a year.

Add to that the fact that for eons, we have been selectively breeding most fruits and vegetables for taste, and that means high sugar. The original apples were more like modern crabapples than the apples of today.

So why are we fat? We eat foods that should be eaten before the starvation season all year long, and in addition, we have eliminated the starvation season.

We unknowingly did this to ourselves.

That's my take anyway. It's non-scientific, but it seems logical to me.

Bob
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  #5   ^
Old Thu, Jun-27-19, 09:27
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WereBear WereBear is offline
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Plan: Epi-Paleo/IF
Stats: 220/137/150 Female 67
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Progress: 119%
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I agree, Bob. We didnít know how it worked and we messed with it anyway.

As always, I blame Ancel Keys. Bad scientist.
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