Brown Fat - The Good Fat

Have you heard all the buzz about brown fat? Scientists have known about brown adipose tissue for years, but only recently have they discovered the link between brown fat, white fat, and burning fat. Also, for a long time, scientists assumed that adults didn’t possess any brown fat cells, but now they know that most adults do, in fact, have small pockets of brown fat, usually in the neck or upper chest. The brown fat and fat loss connection has been reported in several prominent studies, sites, and periodicals, including the New York Times, Nature, The Journal of Clinical Investigation, Huffington Post, Scientific American, Science Daily, Medical News Today, Time, the New England Journal of Medicine, Popular Mechanics, and others. Studies have been conducted and reviewed by endocrinologists, cell biologists, medical doctors, and plastic surgeons in the United States, Canada, the Netherlands, Sweden, and Finland. For anyone who’s ever struggled with how to lose weight, the discoveries about brown fat and weight loss are very exciting!

Okay, you know what white adipose tissue or fat is, right? Some doctors and scientists call the pale form of fat “yellow fat,” while others refer to it as “white fat.” You’ve seen white fat in steaks, pork chops, hamburger meat, ham, and other meats you’ve prepared and eaten. Humans have white fat, too, but we weren’t born with large amounts of it. Instead, we were born with larger amounts of brown fat – adipose tissue that has a brownish color. The color comes from iron and the mitochondria contained in the fat cells.

Brown fat is found only in mammals, and its purpose is to help generate heat. It’s most abundant in human newborns and mammals that hibernate. Rodents also have extra amounts of brown fat because they’re unable to shiver in order to maintain their body heat.

In many ways, brown fat is actually more like muscle tissue than it is like white fat. In fact, most scientists now believe that the cells of both brown fat and skeletal muscles started with the same embryonic stem cells. Another way that brown fat cells differ from white fat cells is that the white fat cells are made up of one big drop of fat, while brown fat cells are made up of lots of tiny drops of fat.

Brown fat needs a lot of oxygen, so the cells are rich in capillaries. These cells are capable of burning fat from white fat cells. According to an article that appeared in the New York Times, an endocrinologist named Dr. Andre Carpentier discovered that when brown fat cells exhaust their own small stores of fat, they turn to burning fat from white fat cells. Carpentier, who works at Quebec’s University of Sherbrooke, along with his colleagues, proved this by doing PET scans on adult human males. The men were subjected to cold temperatures but were not chilled enough to induce shivering. The scans revealed that the brown fat helped to keep the men warm, and it also increased their metabolic rate by a whopping 80%. The results of Dr. Carpentier’s latest study appears in The Journal of Clinical Investigation.

As has already been mentioned, we humans are born with relatively large amounts of brown fat, but as we age, the brown fat cells diminish. Studies conducted on mice, however, show that white fat can be turned into brown fat with adequate exercise. This was discovered in a recent study conducted by Bruce Spiegelman, a cell biology professor at the Dana-Farber Cancer Institute. Spiegelman and his colleagues observed that when the rodents exercised, their muscle tissue excreted irisin, a hormone. The irisin triggered the conversion of regular adipose tissue into brown adipose tissue. The interesting point here is that humans have irisin, too, and our irisin is exactly the same as the irisin in mice.

Chilly temperatures also cause brown fat cells to become active. In fact, some researchers have found that when healthy adults are exposed to cold air, their brown fat cells increase their metabolic rate fifteen times over. That means the cells are burning fat in order to produce heat. It’s also interesting to note that humans who are often exposed to cold air, as with those who work outdoors during the winter months, have large amounts of brown fat. You don’t need to become a cross-country skier to get results, however. One recent study showed that being exposed to chilly temperatures for just fifteen minutes a day can cause your brown fat cells to kick in, but you need to get chilled on a regular basis.

In addition to burning fat and keeping individuals warm, there appear to me even more benefits of brown fat. In mice, there’s a connection between this “good fat” and osteoporosis. Mice that can’t make adequate amounts of brown fat cells have very low bone density. Could triggering the amount of brown fat production in humans be a way to combat osteoporosis?

More benefits of brown fat have been suggested by Dr. James Lyons, a plastic surgeon. Lyons states that brown fat can actually make us look younger by supporting the skin. On WebMD, Lyons is quoted as saying, "I have spent years as a plastic surgeon looking at fat under the skin and have seen how diet and exercise can internally change your fat, rejuvenate your appearance, and enhance weight loss."

Practically all humans who are thin or are of normal weight have small amounts of brown fat cells, but it’s rarely found in the obese. Some doctors and scientists think that the lack of brown fat might point to the reason for obesity, while others suspect that the brown fat isn’t present in obese humans because they don’t need it to maintain their body temperature – their white fat is adequate enough to serve as “insulation” against the cold.

What if irisin can be used in humans to increase the amounts of brown fat? This could be a real breakthrough for weight management and a way to lose weight – especially a way to lose fat. If taking irisin orally or via injection could increase brown fat and turn bad fat into good fat, it stands to reason the metabolism would be increased. This, of course, would theoretically result in white, or “bad,” fat loss. If we could lose the fat in the white adipose tissue and replace it with brown fat cells, the theory is that we’d be thinner, healthier, and younger looking.

How to lose weight with added stores of brown fat? The average adult female has about ½ ounce of brown fat, while the average man has about ¼ ounce of brown adipose tissue. A physician at Boston’s Joslin Diabetes Center, Dr. Aaron Cypress, believes that if the amount of brown fat in humans could be increased to three ounces, an extra 500 calories per day could be burned, without dieting. That might not sound like much, but in a week, that would equal 3,500 calories, or a one-pound weight loss. That’s fifty-two pounds in a year, with no effort.

Some doctors are pretty skeptical about manipulating brown fat cells as a way to lose weight. While they usually concede the benefits of brown fat, they aren’t sure about long term effects because these haven’t been studied yet. Some doctors believe that if humans were to be able to increase their stores of brown fat, hunger levels would be triggered, so humans would just consume more calories to make up for the fat loss and increased metabolism. These scientists and physicians aren’t convinced that “tweaking” nature in order to lose weight might not have some serious side effects. For example, it’s important to note here that humans with the largest amounts of brown fat are usually those who suffer from hyperthyroidism and certain types of cancers. But if the irisin could be administered in a safe manner, it might serve as an effective means for those wanting to know how to lose weight without grueling exercise or very low-calorie diets. You can bet the weight loss and weight management industries will be keeping a close eye on future brown fat studies.