Researchers at Johns Hopkins have discovered that suppressing a protein in the brain of rats not only reduces the animals’ calorie intake but seems to have turned the typical white fat into a brown kind that burns off more energy.

The researchers say someday maybe people could be given an injection of brown fat, usually found in babies but not adults, and that could stimulate weight loss.

“If we could get the human body to turn 'bad fat' into 'good fat' that burns calories instead of storing them, we could add a serious new tool to tackle the obesity epidemic in the United States,” said study leader Dr. Sheng Bi, in a statement.

Government data shows that two-thirds of American adults are overweight and more than a third are obese.

In the study, published in the journal Cell Metabolism, the researchers had been looking to see the effect of suppressing the appetite-stimulating neuropeptide Y (NPY) protein in the brain. It did, which wasn’t a surprise, said Bi, an associate professor of psychiatry and behavioral sciences at the Johns Hopkins University School of Medicine.

But when they went to look at the animals after the experiment, they were surprised to see more brown fat in the rats with suppressed proteins. The researchers say the brown fat may not totally disappear in adults, but may normally be inactive and stored in stem cells.