Green tea has been studied for its beneficial effects on cardiovascular and metabolic diseases. Epigallocatechin gallate (EGCG) is the most abundant green tea catechin and is considered the most bioactive constituent that can reduce body weight by decreasing fat cell differentiation and proliferation. One study has demonstrated that green tea extracts and drinks could reduce body weight and body mass index in obese individuals in 2 months. (Basu A, et al. Green tea supplementation affects body weight, lipids, and lipid peroxidation in obese subjects with metabolic syndrome. J Am Coll Nutr 2010;29:31-40.) On the other hand, a study by some of the same authors of the current study found that 302 mg of EGCG daily did not reduce weight in obese women. (Hsu C, Sai T, Kao Y, et al. Effect of green tea extract on obese women: a randomized, double-blind, placebo-controlled clinical trial. Clin Nutr 2008;27:363-370.) The current study set out to increase the concentration of EGCG to a daily dose of 856.8 mg/day to examine the effects on weight in obese individuals.
This randomized, double-blind trial was conducted in 115 women with central obesity with 102 of them having a body mass index (BMI) >27 kg/m2 and a waist circumference > 80 cm. Women were randomized to either a high dose green tea group or placebo group for 12 weeks. One capsule of green tea or placebo was given three times per day, 30 minutes after meals for a total daily dose of 856.8 mg EGCG.
Body weight decreased from 76.8 kg to 75.7 kg after 12 weeks in the EGCG group. BMI and waist circumference were reduced from 31.0 cm to 30.6 cm and 95.1cm to 92.8 cm respectively. In the placebo group, only waist circumference and hip circumference reached significant reduction from 95.7 cm to 91.5 cm and 107.2 cm to 103.7 cm respectively. No differences were seen in weight or BMI.
The study also demonstrated a trend of decreased total cholesterol and decreased LDL cholesterol. Significantly lower ghrelin levels and elevated adiponectin levels were also seen in the green tea group than in the placebo group.
Commentary: Obesity is one of the most challenging issues in women’s health care. No one strategy produces consistent results in all women. Nutritional modifications, exercise programs, behavioral therapy, and agents that can affect insulin resistance, fat burning, fat oxidation and metabolic rates occupy central roles in efforts. Green tea and its main components, the catechins, including EGCG, are thought to influence body weight through mechanisms of thermogenesis and fat oxidation. The results of the current study with significant weight reduction and decreased ghrelin levels after EGCG treatment implies that a high dose of EGCG might increase energy metabolism and interrupt lipid accumulation and directly inhibit ghrelin secretion.
For perspective on dosing, one might look for a capsule of green tea extract of approximately 330 mg of which 45% is EGCG. If 2 capsules 30 minutes after each meal (three times per day), this would then be close to 900 mg of EGCG per day, slightly more than the 856.8 mg in the current study.
Chen I, Liu C, Chiu J, Hsu C. Therapeutic effect of high-dose green tea extract on weight reduction: a randomized, double-blind, placebo-controlled clinical trial. Clinical Nutrition 2015 1-8 (article in press)