Drinking red grape juice or wine could improve the health of overweight people by helping them burn fat better, according to a recent study.

Researchers at Oregon State University found that consuming dark-colored grapes, whether eating them or drinking juice or wine, might help people better manage obesity and related metabolic disorders such as fatty liver.

Ellagic acid, one of the chemicals found in grapes, proved particularly potent: It dramatically slowed the growth of existing fat cells and formation of new ones, and it boosted metabolism of fatty acids in liver cells.

However, the plant chemicals are not a weight-loss miracle.

"We didn't find, and we didn't expect to, that these compounds would improve body weight," researcher Neil Shay said. "If we could develop a dietary strategy for reducing the harmful accumulation of fat in the liver, using common foods like grapes that would be good news."

For the study, researchers supplemented the diets of overweight mice with extracts from Pinot noir grapes harvested from Corvallis-area vineyards.

Some of the mice were fed a normal diet of "mouse chow," as Shay calls it, containing 10 percent fat. The rest were fed a diet of 60 percent fat -- the sort of unhealthy diet that would pile excess pounds on a human frame.

The grape extracts, scaled down to a mouse's nutritional needs, were about the equivalent of one and a half cups of grapes a day for a person.

"The portions are reasonable which makes our results more applicable to the human diet," Shay added.

When Shay and his colleagues analyzed the tissues of the fat mice that ate the supplements, they noted higher activity levels of PPAR-alpha and PPAR-gamma, two proteins that work within cells to metabolize fat and sugar.

The goal of his work, he added, is not to replace needed medications but to guide people in choosing common, widely available foods that have particular health benefits, including boosting metabolic function.

The findings are detailed in the Journal of Nutritional Biochemistry.