Oolong tea increases energy expenditure and fat oxidation. It appears to suppress food intake and weight gain based on experimental animal studies.
Tea polyphenols inhibit the activity of catechol-O-methyl transferase, which inactivates catecholamines.
The characteristic that separates oolong tea from green tea and black tea is that it is partially fermented. Green tea is unfermented and black tea is fully fermented. This partially fermented characteristic makes it contains a unique tea flavanols which is commonly referred as catechins.
A water extract of oolong tea prevented the obesity and fatty liver induced by a high-fat diet in mice. The consumption of oolong tea over a 6-week period resulted in significant weight loss in women, thus exemplifying the clinical efficacy of oolong tea. The consumption of oolong tea promoted energy expenditure and fat oxidation in human subjects.