It’s time you take a break now. Researchers at the Joslin Diabetes Center have good news for you. Apparently, human adults still have a type of “good” fat previously believed to be present only in babies and children. This fat behaves remarkably unlike any other. Known as brown fat, this fat is active in burning calories and using energy, unlike white fat, which hangs over belt buckles and swings from the backs of arms and stores energy and comprises most body fat.

 

“The fact that there is active brown fat in adult humans means this is now a new and important target for the treatment of obesity and type 2 diabetes,” said C. Ronald Kahn, MD, senior author and Head of the Joslin Sction on Obesity and Hormone Action and the Mary K. Iacocca Professor of Medicine at Harvard Medical School.

 

More exactly, obesity and other metabolic disorders could be treated by stimulating brown fat growth to control weight and improve glucose metabolism.

 

For the study, the researchers analyzed a database of 1,972 patients who had nuclear (PET) or X-ray (CT) imaging scans during a three-year period for a variety of reasons. They found significant brown fat deposits in 7.5 percent of female patients and in over 3 percent of male patients.

 

“These numbers clearly represent an underestimate, since PET/CT can only detect collections of brown fat cells of a certain size and activity, and could miss smaller and less active deposits,” Kahn said.

 

Furthermore, the researchers identified 33 other patients whose pathology records had indicated the presence of brown fat in their necks in the same places where the PET/CT scans had identified the largest concentrations of brown fat. They tested the tissue of two of those patients and detected the presence of a special heat-generating protein called UCP-1 that is unique to brown fat.

 

“These findings suggest that there is previously unrecognized, heat-generating brown fat in many adults,” said lead author Aaron Cypess, M.D., Ph.D., a Research Associate and Staff Physician at Joslin.

 

The study found that younger patients were more likely to have larger amounts of brown fat, and the brown fat was more active during winter time, keeping with its role of burning energy to generate heat.

Also, people who were thin and had normal blood glucose levels also had more brown fat than other people. This finding suggests that brown fat is involved in in regulating body weight and that higher levels of brown fat may protect against obesity.

 

The study was published in Thursday’s issue of The New England Journal of Medicine.