Effect of green tea extract on obese women: A randomized, double-blind, placebo-controlled clinical trial

Aims: To examine the effect of green tea extract (GTE) on obese women and to explore the relationship between GTE and obesity-related hormone peptides. Methods: A randomized, double-blind, placebo-controlled clinical trial was conducted from July 2006 to June 2007 in Taipei Hospital, Taiwan. Seventy-eight of 100 obese women aged between 16 and 60 years with BMI > 27 kg/m² and who had not received any other weight control maneuvers within the last 3 months completed this study. The subjects were randomly divided into Groups A and B. Group A (n = 41) received GTE while Group B (n = 37) took cellulose as a placebo, one capsule (400 mg) three times each day for 12 weeks. The body weight (BW), body mass index (BMI) and waist circumflex (WC) were measured at the beginning of the study and after 12 weeks of treatment with GTE. The data were compared and expressed as % reduction. Results: There was only a 0.3% reduction in BW (0.15 kg) after 12 weeks of treatment with GTE. There was no statistical difference in % reduction in BW, BMI and WC between the GTE and placebo groups. Within group comparison revealed that the GTE group had significant reduction in LDL-cholesterol and triglyceride, and marked increase in the level of HDL-cholesterol, adiponectin and ghrelin. On the other hand, the placebo group showed significant reduction in triglyceride only, and a marked increase in the level of ghrelin alone. Conclusions: This study showed no statistical difference in % reduction in BW, BMI and WC between the GTE and placebo groups after 12 weeks of treatment. The intake of GTE (491 mg catechins containing 302 mg EGCG) for 12 weeks is considered safe as shown by the results.