Antioxidant compounds in green tea could help promote exercise-induced abdominal fat loss, according to a new study from the American Society of Nutrition.
Cetechins are a sub-class of flavonoids, or antioxidant compounds. Green tea is a rich source of catechins, which are thought to play a beneficial role in reducing the risk of various diseases, including Alzheimer's, certain cancers, cardiovascular and oral health.
Precious studies have also suggested that tea catechins may help promote weight loss. The current study, published in The Journal of Nutrition, found that consuming a beverage containing green tea catechins (625mg/d) may enhance exercise-induced loss of abdominal fat and improve triglyceride levels.
Researchers recruited just over 100 adults between the ages of 21 and 65. The participants were all healthy and “normally sedentary”, with a mean BMI of 32kg/m². Most subjects were of non-Hispanic white ethnicity.
Male participants, who made up about half of the total study group, had a waist circumference of over 90cm, while women had a waist circumference of over 87cm. Cholesterol levels were over 5.2mmol/L.
The subjects were randomly assigned to receive either 500ml per day of a beverage providing 625mg catechins, or a control beverage containing added caffeine to match the caffeine content of the catechin beverage.
Both the active and the control beverage contained water, sodium chloride, artificial citrus flavouring, glucose, erythritol, and sucralose. Each 500ml serving provided 63kj (15 Kcal) of energy. Participants agreed not to consume more than two caffeinated beverages per day, including the study product, during the 12-week study period.
Participants consumed one serving of their assigned beverage per day, at any time of the day, and with or without food. They continued their usual energy intake, and three-day diet records were taken at baseline, six and 12 weeks.
During the study period, the subjects committed to 180 minutes of “moderate-intensity” physical activity per week, and to attend at lease three supervised exercise sessions per week.
Body weight loss
At the end of the study period, people in the catechin group were found to have lost more body weight compared to the control group (P = 0.079).
There were no significant differences between the two groups in changes in waist circumference or fat mass. However, both total abdominal fat area (P = 0.013) and abdominal subcutaneous fat area (P = 0.019) had decreased more in the catechin group.
The researchers concluded: “The findings of this study suggest that consumption of a beverage containing green tea catechins (625mg/d) may enhance exercise-induced loss of abdominal fat and improve circulating FFA and TG levels. Additional research is warranted to further clarify the mechanisms responsible for these effects.”
Tea catechins and exercise-induced weight loss
The Journal of Nutrition
doi: 10.3945/jn. 108098293
Authors: Kevin C. Maki, Matthew S. Reeves, Mildred Farmer, Koichi Yasunaga, Noboru Matsuo, Yoshihisa Katsuragi, Masanori Komikado, Ichiro Tokimitsu, Donna Wilder, Franz Jones, Jeffrey B. Blumberg and Yolanda Cartwright