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Surprisingly, not all fat is bad for you. Of the two main types of fat, brown fat and white fat, white fat is more commonly found in the body. White fat is responsible for the functions that we typically associate with fat: storing energy and producing hormones that are released to the rest of the body. Brown fat, on the other hand, is much less prevalent, and it is a much better defense against obesity. Unlike white fat, which stores energy in large fat droplets, brown fat stores energy in small fat droplets that are burned to produce heat.

Brown fat cells have an abundance of mitochondria, which are cellular organelles responsible for generating energy. They also contain iron, which gives the fat its brown color. Brown fat makes up 5% of an infant’s total body mass, but this number decreases with age. Adults have small amounts of brown fat located in the neck and shoulders.

 Human brown fat cells

Image Source: Visuals Unlimited, Inc./Dr. Gladden Willis

In mice, brown fat has been shown to burn more calories when a mouse overeats, thereby protecting them from gaining extra weight. There is also evidence of an association between high brown fat levels and lower body weight in humans.

A new drug called GC-1 takes advantage of the obesity-preventing properties of brown fat. Kevin Phillips, PhD, a researcher from Houston Methodist Research Institute, performed a study testing the experimental drug in mice. In a period of approximately two weeks, he reported that genetically obese mice lost more than half their fat mass and showed increased insulin sensitivity. Similar improvements were recorded for mice with diet-induced obesity.

Phillips explains that the drug works by activating receptors for thyroid hormone, a hormone that plays a role in the regulation of metabolism. GC-1 drastically increases the body’s metabolic rate, which causes white fat to essentially convert to calorie-burning brown fat. “Our data demonstrate that GC-1 is a novel fat-browning agent that may have use in the treatment of obesity and metabolic disease,” says Phillips.

Although GC-1 has not yet been tested in humans for weight loss, it is currently undergoing clinical trials under the name sobetirome for lowering cholesterol. The doses of sobetirome used in the clinical trials, however, are too low to cause weight loss.

Feature Image Source: Fat Power! by jooleeah_stahkey

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