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Brown Fat An Ally in Obesity Battle?

Researchers have found that mice exposed to low temperatures metabolize body fat more quickly and develop more blood vessels in their adipose tissue, where energy in the form of fat is stored.

The study about the discovery, which could combat obesity and diabetes, was published in the January issue of the journal Cell Metabolism by researchers at Stockholm, Sweden's Karolinska Institutet (which awards the Nobel Prize in physiology or medicine).

"This is the first time it's been shown that blood vessel growth affects the metabolic activity of adipose tissue rather than vice versa," said professor Yihai Cao, lead study author, in a release. "If we can learn how to regulate the development of blood vessels in humans, we'd open up new therapeutic avenues for obesity and metabolic diseases like diabetes."

Oxygen and blood-borne nutrients are necessary to make fat cells grow and enable the metabolic process to function. So the researchers figured that the amount of body fat could be regulated - and, perhaps, obesity reduced - by a more rapid development of blood vessels in the adipose tissue. When mice in the experiment were exposed to low temperatures, that's exactly what happened.

The growth of more blood tissues was followed by a transformation of the adipose tissue from "white" fat to "brown" fat. Brown fat has a higher metabolic activity and breaks down more quickly, releasing heat when it does.

Brown fat is found mainly in most rodents and hibernating animals, but in humans only newborn babies contain the specialized tissue. Because the fat breaks down into heat rather than energy, it is believed to be a key factor in allowing hibernating animals to survive the long winters, as they are unable to shiver or perform other activities to keep themselves warm.

Brown fat has increasingly been targeted for a possible role in weight loss therapy for humans; this study suggests that in controlling blood vessel development, adults might actually be able to turn white fat into brown.