Submitted to: Journal of Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/6/2008
Publication Date: 2/1/2009
Citation: Maki, K.C., Reeves, M., Farmer, M., Yasunaga, K., Matsuo, N., Katsuragi, Y., Komikado, M., Tokimitsu, I., Wilder, D., Jones, F., Blumberg, J., Cartwright, Y. 2009. Green Tea Catechin Consumption Enhances Exercise-Induced Abdominal Fat Loss. Journal of Nutrition. 139:264-270.
Interpretive Summary: Obesity is a major public health problem among over 72 million adults in the United States classified as overweight or obese. Obesity is associated with an increased risk of many chronic diseases, including hypertension, heart disease, diabetes, and some types of cancers. Catechins, the principal phytonutrients in green tea, have been suggested to have anti-obesity effects in both animal and human studies, e.g., increased fat oxidation and energy expenditure as well as decreased body fat and weight have been reported with catechin consumption. Thus, we designed a 12-week, randomized clinical trial to evaluate the influence of a green tea catechin-containing beverage (compared to placebo) on body composition and fat distribution in overweight and obese adults during an exercise-induced weight loss program. During the intervention, there was a trend toward greater loss of body weight in the catechin group compared with the control group. No significant difference between groups was noted for change in total fat mass at the end of the study but significant decreases were achieved in abdominal and subcutaneous abdominal fat areas and in serum triglycerides in the catechin group compared to the control group. Therefore, consumption of green tea catechins may enhance exercise-induced changes in abdominal fat and serum triglycerides.
Technical Abstract: Aim: This study evaluated the influence of a green tea catechin beverage on body composition and fat distribution in overweight and obese adults during exercised-induced weight loss. Methods: Participants (N=132) were randomly assigned to receive a 500 mL beverage containing approximately 625 mg of catechins or a control beverage once daily for 12 weeks. Subjects were asked to maintain constant energy intake and engaged in low to moderate intensity exercise, with a target of >/- 180 min/week. Body composition (dual x-ray absorptiometry) and abdominal fat areas (computed tomography), and clinical laboratory tests were measured at baseline and week 12. Body weight was measured at bi-weekly clinic visits. Results: There was a trend toward greater loss of body weight in the catechin group compared with the control group: least squares mean (95% confidence interval) changes, adjusted for baseline value, age and sex, were -2.2 (-3.1, -1.3) and -1.0 (-1.9, -0.1) kg, respectively, P = 0.079. Percentage changes in fat mass did not differ significantly between the catechin and control groups: -5.2 (-7.0, -3.4) vs. -3.5 (-5.4, 1.6), P = 0.208. However, percentage changes in total abdominal fat area [-7.7 (-11.7, -3.8) vs. -0.3 (-4.4, 3.9), P = 0.013], subcutaneous abdominal fat area [-6.2 (-10.2, -2.2) vs. 0.8 (-3.3, 4.9) P = 0.019] and fasting serum triglycerides [-11.2 (-18.8, -3.6) vs. 1.9 (-5.9, 9.7), P = 0.023] were significantly larger in the catechin group. Conclusion: Green tea catechin consumption enhances early exercise-induced changes in abdominal fat and serum triglycerides.