#brown fat

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The Scientific Research Notes of S. Sunkavally. Years: 1986 - 1990.

Page 149.

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Physical activity decreases the risk of a network of diseases, and exercise may be prescribed as medicine for lifestyle-related disorders su

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Weight-loss breakthrough easily hacks white fat to turn calorie-burning beige

By suppressing just one protein, stores of white fat can switch to becoming calorie-burning beige fat, in a feat that so far has eluded scientists working on this long-studied area of obesity treatment.

University of California San Francisco researchers found that by suppressing the protein KLF-15 – which they'd earlier identified as playing a role in cell metabolism, and one that is far more abundant in calorie-burning beige and brown fat – the cells themselves switched their function. And without the protein present, the default setting for fat cells appeared to be beige, not the predominant white. “A lot of people thought this wasn’t feasible,” said Brian Feldman, MD Distinguished Professor in Pediatric Endocrinology and senior author of the study. “We showed not only that this approach works to turn these white fat cells into beige ones, but also that the bar to doing so isn’t as high as we’d thought.” Previously, scientists had focused on turning stem cells into calorie-burning brown or beige fat, which is essentially used by our bodies as fuel for temperature regulation. As such, these cells burn through fat stores, whereas white adipose tissue are the stores we find so hard to shift in weight loss.

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CRISPR Gene Editing Could Help You Stay Thin

White fat cells are the ones filled with a lipid that make up fatty deposits – and human adults have lots of them. There’s another type called brown fat cells, which we don’t have many of. They are the ones that burn and store energy. As people age or gain...

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Brown Fat vs White Fat

What is brown fat? Interestingly, and something that isn’t too well known, is that the fat in our body is categorized into two colours: White Cell Fat (also known as White Adipose Tissue, WAT), and Brown Cell Fat (Brown Adipose Tissue, BAT). The brown colour is also sometimes referred to as beige or brite.

What is the purpose of body fat? Each kind of fat serves a different purpose. White Fat: is the standard fat that you’ve likely known your whole life. It is the fat that stores energy from excess calorie consumption and accumulates around the body in large lipids (fat droplets). The accumulation of fat helps keep you warm by literally providing insulation around your organs. In humans, too much white fat is not a good thing. It leads to obesity, and a higher risk of heart disease, diabetes, and other diseases. Brown Fat: stores energy in smaller spaces than white fat. It’s packed with iron-rich mitochondria, which is how it gets its brown colour. When brown fat burns, it creates heat without shivering. During this process, brown fat also burns calories. Scientists used to believe only babies had brown fat (which makes up about 5% of their body mass). They thought by the time people reached adulthood, all their brown fat disappeared. What researchers now know is that even adults have small reserves of brown fat, typically stored in small deposits around the shoulders and neck. How to get brown fat In a way, brown fat is “good” fat. Humans with higher levels of brown fat in their bodies have lower overall body weights. All people have some “constitutive” brown fat, which is the kind you are born with. There’s also another form that considered “recruitable” fat. This means it can change to brown fat under the right circumstances. This recruitable type is found in muscles and white fat throughout your body. There are certain drugs that can cause the browning of fat. Thiazolidinediones (TZDs), a drug used to help manage insulin resistence, can help with brown fat accumulation. However, this drug is also associated with weight gain, fluid retention, and other side effects. So it can’t be used as a quick fix.

Turn the temperature down Exposing your body to cool, even cold, temperatures below 19C (66F) may help recruit more brown fat cells. Research by scientists Paul Cohen and Bruce Spiegelman in July of 2015 found that just two hours of exposure to colder temperatures increases your bodies recruited brown fat mass.

Exercise Other research by Mark Jedrychowski and Christiane Wrann found that, in mice, regular aerobic exercise increased the production of the protein called irisin, which is responsible for turning white fat into brown fat. In human studies, those with a sedentary lifestyle produced far less irisin than those with a moderately active lifestyle.

Brown Fat and Other Research We are still trying to understand the genes that control how white and brown fat develop. In one study done with mice, researchers engineered the mice to be born with very little brown fat by limiting a protein receptor called Type 1A BMP. When exposed to cold, the mice created brown fat from their white fat and muscles anyway, showing the power of recruitment. Researchers have also discovered that a certain protein called B-call Factor-2 (Ebf2) may play a key role in building brown fat. When engineered mice had exposure to high levels of Ebf2. it transformed white fat to brown fat. These cells consumed more oxygen, which is a sign that the brown fat was indeed producing heat and burning calories.

So, there you have it. Brown vs White fat in a nutshell. this is the second time I have written this up, I will scream if it won’t post.

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Why brown fat is good for people’s health

Brown adipose fat (BAT) may help to protect against diabetes and obesity. BAT serves as a key metabolic filter that controls branched-chain amino acid clearance, contributing to better overall metabolic health.

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The color of body fat might affect how trim people are

Brown fat burns calories to keep us warm. Researchers are searching for ways to boost it to help fight obesity and diabetes.

Fat sometimes gets a bad rap. It’s often linked with being overweight and poor health. But fat is an essential part of all living things. In our own bodies, fat lies beneath the skin and hugs our organs. Its job is to store extra calories until needed. Seems like a straightforward role. Or is it?

In fact, body fat is complex. Until recently, scientists thought people had only one type. Called white fat, it stores excess calories in molecules called lipids. Lipids can be broken down for energy when food is hard to find. White fat is what people think of when they think of body fat.

Explainer: All about the calorie

But some 50 years ago, researchers discovered that people also have brown fat. It actually burns calories.

Scientists first discovered brown fat about 500 years ago. They found it in hibernating marmots (also known as groundhogs or woodchucks). Only a small amount of body fat is brown. So for a long time, scientists thought brown fat was a gland that existed only in hibernating animals. Only in the last 100 years have they realized this “gland” is actually a special type of fat.

Scientists are still learning about brown fat. Studies have uncovered its importance for hibernating animals. That research helped show that brown fat plays a key role in how bodies use energy. And that link suggests that boosting brown fat in people might help them lose weight and perhaps treat certain chronic diseases, such as diabetes.

Wake-up call

Most body fat in animals, including people, is white. And it’s a life-saving tissue. Most animals don’t have a constant supply of food. Until fairly recently, most people didn’t either. White fat allows individuals to eat more than they need when food is easy to find. It stores those extra calories until food becomes scarce. Then the body burns it for energy to stay alive until more food shows up.

Explainer: How brief can hibernation be?

Hibernating animals take this to the extreme, explains Mallory Ballinger. She is an evolutionary biologist at the University of California, Berkeley. Hibernation allows many animals to get through harsh winter conditions. Bats, squirrels and bears, for example, all gorge themselves on food in fall. These mammals pack on the pounds — up to half their body weight — in preparation for a long, cold winter.

Animals don’t eat when they’re hibernating. Instead, they burn their white fat to keep their bodies running. But they only have so much fat to burn. To make it last an entire winter, these critters must use it slowly. Much more slowly than they normally would. To do this, they enter a state called torpor.

Scientists Say: Torpor

When in torpor, animals appear to be sleeping. But torpor goes much deeper than that, Ballinger says. In torpor, a body’s activities slow down. The heart may beat only a few times each minute. Breathing may become irregular. An animal may take several breaths and then stop breathing for several minutes — even up to an hour or more. Bodies in torpor also chill down. Instead of wasting energy keeping warm, a hibernating animal’s body can remain just above freezing.

But hibernating animals don’t stay in torpor all winter, Ballinger points out. Every week or two, they waken. And they stay awake for a day or so before going back into torpor. Biologists don’t know what triggers the wake-up or why it happens, she says. The duration and timing varies by species. However, she points out, all true hibernators go through this cycle.

This dormouse will hibernate for a whopping seven months, waking every few weeks for about a day each time. The animal’s stores of brown fat help keep it from freezing. CREDIT: SashaFoxWalters/iStock/Getty Images Plus

In order to wake up, the animals have to warm up. That means going from a temperature just above freezing to their normal body temp in only a couple of hours.

That’s where brown fat becomes important. Brown fat creates heat. If the outside temperature gets too cold, brown fat keeps the animal from freezing. It also pulls the animal out of torpor. As the brown fat gives off heat, it warms the blood, which then carries that warmth to the rest of the body.

This process burns up white fat, including white droplets packed in with the brown fat cells, Ballinger explains. That shows brown fat plays a critical part in how and when the body stores and uses energy. And it turns out that’s true not only in hibernating animals. It’s true in people, too.

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Micro Diet

After a year’s various indulgences, some of us will make resolutions to exercise more. This not only burns off calories, but also fuels the body’s capacity to keep weight under control, in part by boosting microRNAs – small strands of genetic material that can promote energy use. An alternative way to trigger this process might help people accomplish their weight-loss goals. A new study has looked at how enoxacin – an antibiotic rarely used any more – can encourage metabolism in cells and hence keep weight down. In experiments with mice, it caused microRNAs to make obesity-promoting white fat (which stores surplus energy as fat) behave like brown fat (which turns food to heat), and increased energy expenditure in cells (enoxacin-stimulated fat cells pictured). Enhancing our body’s natural ability to prevent obesity could help tackle a growing health problem, and maybe make next year’s indulgences a little less costly.

Written by Anthony Lewis

Image from work by Andréa Livia Rocha and colleagues

Department of Biochemistry and Tissue Biology, Institute of Biology, University of Campinas, Campinas, Brazil

Image copyright held by the original authors

Research published in Science Advances, December 2020

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