A compound found in plants and some Chinese herbal medicines may trigger the body to burn calories by stimulating the activity of heat-producing tissue called brown fat, a new study in mice found.

In the study, researchers found that the mice that were injected daily with the compound, called berberine, for four weeks burned more calories than the mice that were not injected with the compound. In addition, the bodies of the mice injected with berberine generated more heat when they were exposed to cold air between 39 and 46 degrees Fahrenheit (4 to 8 degrees Celsius) than the mice that were not injected with the compound.

The researchers also found that berberine seemed to protect the mice from weight gain during the study period.

"Our works demonstrate the positive function of [berberine] in energy balance," said study author Guang Ning, of the China National Clinical Research Center for Metabolic Diseases.

Unlike white fat, whose main role is to store energy, brown fat burns calories to generate heat to keep the body warm. For example, a studypublished in July in the journal Diabetes showed that men with high levels of brown fat burned more calories than men with low brown-fat levels while they were exposed to low temperatures.

In the new study, the researchers determined that berberine activated brown fat. They also noted that berberine affected the animals' white fat, which began to "brown" meaning it started to acquire the qualities of its calorie-burning cousin.

The new results suggest that berberine could have a similar effect in reducing body weight, at least in mice, Ning said.[13 Kitchen Changes That Can Help You Lose Weight]

However, further research is needed to determine whether the compound could deliver the same effects in people, the researchers said.

"Although our work [yields] exciting results, it remains hard to say that it can be used freely as [a] weight-reducing drug," Ning told Live Science. More research must be done before berberine could be used in a clinical setting. For example, it must be shown that the compound significantly reduces body weight in people, and also that it is safe to take, he said.

At this point, it is not clear how much berberine a person would need to take to see fat-burning results, he said.

Previous research has suggested that berberine has metabolic benefits, including protecting against diabetes and lowering cholesterol levels. In a study of 36 people with type 2 diabetes, published in 2008 in the journal Metabolism, researchers found that the compound reduced the patients' cholesterol and triglyceride levels. However, some of the participants experienced diarrhea, constipation, flatulence and abdominal pain while taking berberine. The most common side effect reported from using berberine is constipation, Ning said.

The new study was published Nov. 25 in the journal Nature Communications.

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