Submitted to: Journal of Nutrition
Publication Type: Peer reviewed journal
Publication Acceptance Date: 8/15/2001
Publication Date: 11/1/2001
Citation: Rumpler, W.V., Seale, J.L., Clevidence, B.A., Judd, J.T., Yamamoto, S., Komatsu, T., Hosoda, K. 2001. The effect of oolong tea on metabolic rate and substrate use in men. Journal of Nutrition. 131:2848-2852. Interpretive Summary: Oolong tea, according to traditional Chinese belief, is effective in the control of body weight. Few controlled studies, however, have been conducted to measure the impact of tea on energy expenditure (EE) of human subjects. In this study we examine the impact of tea consumption on the number of calories a person burns each day while eating a controlled diet. Twelve men participated in the study for 1 month. Each week the participant would consume, 5 times per day, either water, water plus caffeine (same amout of caffeine as in full strength tea) , full strength (1 tea bag per cup of hot water) tea or half strength tea (« tea bag per cup of hot water). The caffinated water and the full strength tea increased the amount of calorie burned by the men by about 3%. In addition the full strength tea increased the amount of fat burned by the men by around 10%. The increase in the amount of fat burned by the men when consuming caffeine was about half as much less as when they consumed the full strength tea. Based on the results of this study the effect of the tea on the number of calories burned was the same as if a person consumed a caffeinated beverage but the amount of fat burned was greater.This suggests that tea may have a beneficial affect on people trying to loose body fat more than other caffeinated beverages.
Technical Abstract: Oolong tea, according to traditional Chinese belief, is effective in the control of body weight. Few controlled studies, however, have been conducted to measure the impact of tea on energy expenditure (EE) of human subjects. A randomized cross-over design was used to compare 24-h energy expenditure of 12 men consuming each of four treatments:1) water, 2) full- tea; daily allotment brewed from15 g of tea, 3) half-tea; brewed from 7.5 g tea, and 4) water containing caffeine, 270 mg, equivalent to the concentration in the full-tea treatment. Subjects refrained from consuming caffeine or flavonoids for 4 d prior to the study. Tea was brewed each morning; beverages were consumed at room temperature as five 300 mL servings. Subjects received each treatment for three days; on the third day, EE was measured by indirect calorimetry in a room calorimeter. For the three days, subjects were given a typical American diet. Calorie content of the diet was tailored to each subject's needs as determined from a preliminary measure of 24-h EE by calorimetry. Relative to the water treatment, EE was increased, on average, 3.4% and 2.9% for the full tea and caffeine treatments and 0.5% for the half-tea treatment. This increase over control represented an additional expenditure of 71, 65 and 11 kcal for subjects treated with full-tea, caffeine, and half-tea, respectively. In addition, fat oxidation was significantly higher (12%)when subject consumed the full strength tea compared to water. A smaller increase in fat oxidation occured when consuming the caffinated water (8%). This suggests that tea may have a beneficial affect on people.