Oolong tea increases metabolic rate and fat oxidation in men

According to traditional Chinese belief, oolong tea is effective in the con trol of body weight. Few controlled studies, however, have been conducted t o measure the impact of tea on energy expenditure (EE) of humans. A randomi zed cross-over design was used to compare 24-h EE of 12 men consuming each of four treatments: 1) water, 2) full-strength tea (daily allotment brewed from 15 g of tea), 3) half-strength tea (brewed from 7.5 g tea) and 4) wate r containing 270 mg caffeine, equivalent to the concentration in the full-s trength tea treatment. Subjects refrained from consuming caffeine or flavon oids for 4 d prior to the study. Tea was brewed each morning; beverages wer e consumed at room temperature as five 300 mL servings. Subjects received e ach treatment for 3 d; on the third day, EE was measured by indirect calori metry in a room calorimeter. For the 3 d, subjects consumed a typical Ameri can diet. Energy content of the diet was tailored to each subject's needs a s determined from a preliminary measure of 24-h EE by calorimetry. Relative to the water treatment, EE was significantly increased 2.9 and 3.4% for th e full-strength tea and caffeinated water treatments, respectively. This in crease over water alone represented an additional expenditure of 281 and 33 1 kJ/d for subjects treated with full-strength tea and caffeinated water, r espectively. In addition, fat oxidation was significantly higher (12%) when subjects consumed the full-strength tea rather than water.