One of the chemicals, ellagic acid, 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.
These plant chemicals are not a weight-loss miracle, cautions Shay. "We didn't find, and we didn't expect to, that these compounds would improve body weight," he said. But by boosting the burning of fat, especially in the liver, they may improve liver function in overweight people.
"If we could develop a dietary strategy for reducing the harmful accumulation of fat in the liver, using common foods like grapes," Shay said, "that would be good news.