Is Brown Fat The Key To A Healthier You?

Friday, April 26, 2013

Is Brown Fat the Key to A Healthier You?

Researchers have found a new way to boost your body's metabolism by activating fat cells, specifically brown fat cells. For the future they envision a "brown fat pill"—a drug that boosts brown fat activity through molecular means, but for now cold showers might produce a similar effect.
Scientists have recently reported significant findings about the location, genetic expression and function of human brown adipose tissue (BAT), and the generation of new BAT cells.  BAT, also known as brown fat was previously thought only to be present in infants and not in adults, but new findings are emerging on the tissue.

Recent research appearing in the journal Nature Medicine, may contribute to further study of brown fat's role in human metabolism and developing treatments that use BAT cells to promote weight loss.

Brown fat has long been known to exist in infants and animals such as mice, but until recently scientists thought it disappeared before human adulthood, leaving only the white fat that's associated with weight gain.

Unlike white fat, which stores energy, chestnut-colored brown fat has been found to burns energy. Brown fat cells contain a large supply of mitochondria, and an enzyme that allows them to release energy from food calories directly as heat. The new research on brown fat only recently confirmed that not only is brown fat common in adults, it's also important to metabolism: Younger, thinner people have more detectable brown fat in their bodies than older, more overweight individuals.

brown fat research

Even today, researchers are still discovering how fat works. Rather than just a blubbery, lifeless mass, fat is now considered to be a sophisticated and scientifically complex biological organ, as important to the body as the liver or the kidneys.

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Scientists believe that fat secretes hormones and signaling molecules that coordinate behavior and health. White fat also plays a significant role in the immune system: Another study published in August in the journal ­Immunity concluded that fat droplets help protect the body against immune-system invaders.

A previous study by Cypess found that the amount of brown fat in individuals was inversely proportional to their body-mass index, especially in older people.

A 2008 study published in Cell Metabolism found that the fat that accumulates around the thighs and hips, called subcutaneous fat, actually lowers risk of diabetes. "We were taught that white fat was something that stores energy very efficiently, and that's it," Cypess says. "Fat has undergone a renaissance."

Previous studies have identified the human neck as a primary location for BAT deposits. To determine the precise locations of these deposits, Joslin scientists obtained fat samples from five neck regions of patients undergoing neck surgery.

Analysis of the samples showed that BAT was most abundant in deep regions of the neck, near the carotid sheath and longus colli muscles. These samples expressed the BAT marker gene, uncoupling protein 1 (UCP1), which is involved in heat generation.

"BAT is most abundant in the deep locations of the neck, close to the sympathetic chain and the carotid arteries, where it likely helps to warm blood and raise body temperature. Now that we know where brown fat is, we can easily collect more cells for further study," says Aaron M. Cypess, M.D., Ph.D., senior author and Assistant Investigator in the Section of Integrative Physiology and Metabolism and Assistant Professor at Harvard Medical School.

In analyzing genetic expression in superficial and deep human neck fat tissue, the fat from deep locations was found to most closely resemble cells from constitutive mouse BAT, the kind already known to consume large quantities of glucose and fat.

The Joslin scientists compared the oxygen consumption rate (OCR), which demonstrates the capacity to burn calories, of human BAT cells to mouse constitutive BAT cells and human WAT. This is the first study to directly measure brown fat cells' OCR at baseline. The OCR of the human BAT cells from the deep location next to the longus colli was nearly 50 percent of the mouse BAT cells; in contrast, the OCR of human WAT was only one-hundredth of the OCR found in the most active human BAT from the longus colli depot. "We show that at baseline, brown fat cells have a great capacity to burn fat," says Dr. Cypess.

The scientists were able to grow new functional brown fat cells (adipocytes) by differentiating precursor cells (preadipocytes) derived from both superficial and deep human neck fat tissue. When stimulated, the cells expressed the same genes as naturally occurring brown fat cells. This is the first report of the production of brown fat cells (adipogenesis) that can respond to pharmacological stimulation.

The Joslin scientists are following up on this study to learn more about the functions of BAT, including how it affects energy balance and uses glucose. Having the ability to produce brown fat cells outside the body will make it possible to develop drugs and other potential treatments that increase BAT activity to combat obesity. "Our research has significant practical applications. If we stimulate the growth of brown fat in people, it may burn their white fat and help them lose weight, which lessens insulin resistance and improves diabetes," says Cypess.

Researcher Patrick Seale identified a protein called PRDM-16 that is present in every brown fat cell but does not exist in  white fat cells. When Seale turned off PRDM-16 activity in young brown fat cells, they transformed into muscle cells. At the University of Pennsylvania School of Medicine, Seale is working on identifying genes that may turn PRDM-16 on.

Bruce Spiegelman, who was Seale's PHD advisor is also testing a therapy that involves removing white fat precursor cells from animals, inserting active PRDM-16 and then transplanting the cells back into the animals to see if they lose weight.

Brown Fat Pill

Ultimately, what Seale and Cypess envision is a "brown fat pill"—a drug that boosts the activity of brown fat through molecular means. "I have patients who are 400 pounds," Cypess says. "I have to find a way to help them out."

Brown fat could help people achieve weight loss goals by burning, say, an extra 500 calories a day.

cold shower

Cold Showers

Is it possible to increase your own brown fat levels?

Until a brown fat pill becomes available, there are ways for people to increase their brown fat activity. It could help to turn down your home's central heating and to spend some time outside in the fall and winter. Studies also suggest that people who work outdoors have higher brown fat activity than average, so it's not absurd to think that walking to work on a brisk day could boost your metabolism.

A team led by Sven Enerbäck, a medical geneticist at the University of Gothenburg in Sweden, found that when subjects spent 2 hours in a cold room wearing thin clothing and intermittently soaking their feet in ice water, their brown fat burned 15 times more energy than it did at room temperature.

One subject had enough brown fat to lose 8 to 9 pounds per year. Dutch researchers found active brown fat in 23 out of 24 subjects when they were cold, but not when they were warm. And research at the University of Nottingham in England revealed brown fat activity was closely associated with seasonal decreases in daylight as well.

In the book, The Brown Fat Revolution: Trigger Your Body's Good Fat to Lose Weight and Be Healthier, author James R. Lyons, explains more of why brown fat is important, and provides some strategies to increase it in your body including a four-week eating plan that alternates carbohydrates and proteins, and a monthly exercise routine centered on weights and bungee cords--not cardio--keeping metabolism up continuously (not temporarily, as cardio does) to burn more fat.

Tim Ferriss also discusses brown fat in his book, The 4-Hour Body.  While there are techniques using ice baths to stimulate brown fat production, Ferriss says that cold showers have less of an effect, but they'll still have an effect.

Cold therapy may also have other benefits.  Daniel Craig is said to have used extreme cold therapy, or cryotherapy, to train for his role as 007 in the recent James Bond film.

SOURCE  Joslin Diabetes Center, Popular Mechanics

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