Green tea molecules are small enough to alter energy metabolism in the liver, whereas black tea molecules are too large. However, according to the study published in the European Journal of Nutrition, researchers discovered that black tea polyphenols stimulate the growth of good gut bacteria and the formation of short-chain fatty acids instead, which have been shown to boost metabolic rate.
Both black tea and green tea were proven to lower the number of gut bacteria linked to obesity while increasing the bacteria responsible for lean body mass. But now there is proof that black tea revs up your metabolism, too. "The results suggest that both green and black teas are prebiotics, substances that induce the growth of good microorganisms that contribute to a person's well-being," said Susanne Henning, lead author of the study and a human nutrition professor at UCLA.
"Our new findings suggest that black tea, through a specific mechanism through the gut microbiome, may also contribute to good health and weight loss in humans," she said, adding that for fans of black tea, "there may be a new reason to keep drinking it."
This story was originally published on Byrdie UK and has since been updated by Hallie Gould.