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The Miracle of Brown Fat

October 12, 2011 No Comments by Scott Isaacs, M.D.

There are two colors of fat, brown fat and white fat. The fat we are most familiar with is white fat, which comprises most of the fat in the body. Most of the fat in our body is white fat. White fat is a storage depot for excess calories and provides insulation. White fat produces inflammation, an unhealthy situation for the body. Brown fat is a healthy type of metabolically active fat. Brown fat is named as such because it contains a lot of energy-generating mitochondria which gives rise to the color. Brown fat is considered “good” fat because it burns calories and generates body heat. There are different types of fat. Fat is actually a series of different types of tissues with different functions. The location of fat matters and that fat in the belly is the unhealthiest type of fat that leads to many of the problems we associate with obesity including insulin and leptin resistance. But location is not the only factor that distinguishes different types of fat.

Through complex brain-hormone interactions, the body controls its own body temperature. A higher body temperature is the result of increased metabolism. It’s like running an engine; the harder it runs, the hotter it gets. The hormones that raise metabolism, in fact, do so mainly by increasing thermogenesis. Low body temperature means lowered metabolism; we’ve seen this is an indicator of low thyroid function. People with more brown fat have a higher body temperature and higher metabolism because they burn more calories to produce body heat.

Brown fat produces a specialized blood protein known as thermogenin that allows for the production of body heat. Brown fat is controlled by nerves and stress hormones. The stress hormones epinephrine and norepinepherine, released from nerve cells and the adrenal gland, activate brown fat, increasing thermogenesis.

Newborn babies have the highest concentrations of brown fat, but until recently, it was thought that adults didn’t have any brown fat. In 2009, scientists discovered the presence of brown fat in adults. This was considered a major medical breakthrough when the research was published in the New England Journal of Medicine. Less than one percent of the body’s fat is brown fat. Most brown fat is located in the front of the neck, shoulders and around the collar bones. Brown fat also hides in deeper layers of fat and the number of brown fat areas varies among individuals. Thinner people and younger people tend to have the most brown fat. Although, you lose brown fat as you get older and as you gain weight, it doesn’t go away completely. In the past, it was thought that once you lost your brown fat, it was gone forever. However, this is clearly not the case. Everyone has the potential of making more brown fat.

Now researchers are working feverishly to find ways to help people make more of this calorie-burning fat. Researchers are investigating different types of medications and even stem cell transplants as ways to induce brown fat production. Animal studies show that lowering room temperature just a few of degrees will make them lose weight by boosting their metabolic Cold also makes white fat act more like brown fat, which burns more calories.

You can make more brown fat by cooling your body down. Even a small decrease in the temperature your body is exposed to will induce your body make more brown fat cells. From a survival perspective, when the body is cooled, it has to make more brown fat to generate enough body heat to keep from freezing to death. Researchers have speculated that warm temperatures may be contributing to our obesity epidemic. Turning down the thermostat just a couple of degrees could help boost your metabolism because you need to burn more calories to stay warm.

Exercise done in the water is particularly good at drawing out body heat, forcing your body to burn more calories. You don’t need to make yourself so cold that you feel uncomfortable or shiver. Swimming is one of the best fat-burning exercises. Swimming is extremely relaxing and a great form aerobic exercise. But any water exercise is a great way to cool your body and burn extra calories. Submersing yourself in water that’s cooler than body temperature will cool you down, causing you to make more brown fat to keep you warm. Try walking in a pool, using a kick board or take a water aerobics class. You don’t have to be a great swimmer to use water to help you burn extra calories.

Just as healthy brown fat can be part of the cycle to help lose weight; dysfunctional brown fat can get in the way. And, ironically – or perhaps not so ironically, considering the constant feedback loops of the body — obesity can cause brown fat dysfunction. If you are very overweight, your brown fat tissue cannot produce heat properly, so your metabolism is lowered and it becomes even harder to lose weight, ad infinitum.

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