title: Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Effects of Green Tea Supplementation on Elements, Total Antioxidants, Lipids, and Glucose Values in the Serum of Obese Patients Effectiveness of green tea on weight reduction in obese Thais: A randomized, controlled trial Green tea catechin consumption enhances exercise-induced abdominal fat loss in overweight and obese adults. Effects of Chinese Green Tea on Weight, and Hormonal and Biochemical Profiles in Obese Patients With Polycystic Ovary Syndrome—A Randomized Placebo-Controlled Trial Effects of green tea on weight maintenance after body-weight loss. Health effects of green tea catechins in overweight and obese men: a randomised controlled cross-over trial. Effect of green tea extract on obese women: a randomized, double-blind, placebo-controlled clinical trial. A green tea extract high in catechins reduces body fat and cardiovascular risks in humans. Long-Term Supplementation of Green Tea Extract Does Not Modify Adiposity or Bone Mineral Density in a Randomized Trial of Overweight and Obese Postmenopausal Women.
abstract: BACKGROUND Current interest in the role of functional foods in weight control has focused on plant ingredients capable of interfering with the sympathoadrenal system . OBJECTIVE We investigated whether a green tea extract , by virtue of its high content of caffeine and catechin polyphenols , could increase 24-h energy expenditure ( EE ) and fat oxidation in humans . DESIGN Twenty-four-hour EE , the respiratory quotient ( RQ ) , and the urinary excretion of nitrogen and catecholamines were measured in a respiratory chamber in 10 healthy men . On 3 separate occasions , subjects were r and omly assigned among 3 treatments : green tea extract ( 50 mg caffeine and 90 mg epigallocatechin gallate ) , caffeine ( 50 mg ) , and placebo , which they ingested at breakfast , lunch , and dinner . RESULTS Relative to placebo , treatment with the green tea extract result ed in a significant increase in 24-h EE ( 4 % ; P < 0.01 ) and a significant decrease in 24-h RQ ( from 0.88 to 0.85 ; P < 0.001 ) without any change in urinary nitrogen . Twenty-four-hour urinary norepinephrine excretion was higher during treatment with the green tea extract than with the placebo ( 40 % , P < 0.05 ) . Treatment with caffeine in amounts equivalent to those found in the green tea extract had no effect on EE and RQ nor on urinary nitrogen or catecholamines . CONCLUSIONS Green tea has thermogenic properties and promotes fat oxidation beyond that explained by its caffeine content per se . The green tea extract may play a role in the control of body composition via sympathetic activation of thermogenesis , fat oxidation , or both The consumption of green tea has been associated with cardiovascular and metabolic diseases . There have been some studies on the influence of green tea on the mineral status of obese subjects , but they have not yielded conclusive results . The aim of the present study is to examine the effects of green tea extract on the mineral , body mass , lipid profile , glucose , and antioxidant status of obese patients . A r and omized , double-blind , placebo-controlled study was conducted . Forty-six obese patients were r and omly assigned to receive either 379 mg of green tea extract , or a placebo , daily for 3 months . At baseline , and after 3 months of treatment , the anthropometric parameters , blood pressure , and total antioxidant status were assessed , as were the levels of plasma lipids , glucose , calcium , magnesium , iron , zinc , and copper . We found that 3 months of green tea extract supplementation result ed in decreases in body mass index , waist circumference , and levels of total cholesterol , low-density cholesterol , and triglyceride . Increases in total antioxidant level and in zinc concentration in serum were also observed . Glucose and iron levels were lower in the green tea extract group than in the control , although HDL-cholesterol and magnesium were higher in the green tea extract group than in the placebo group . At baseline , a positive correlation was found between calcium and body mass index , as was a negative correlation between copper and triglycerides . After 3 months , a positive correlation between iron and body mass index and between magnesium and HDL-cholesterol , as well as a negative correlation between magnesium and glucose , were observed . The present findings demonstrate that green tea influences the body 's mineral status . Moreover , the results of this study confirm the beneficial effects of green tea extract supplementation on body mass index , lipid profile , and total antioxidant status in patients with obesity This study was undertaken to investigate the effects of green tea on weight reduction in obese Thais . A r and omized , controlled trial involving 60 obese subjects ( body mass index , BMI > 25 kg/m2 ) was conducted . All subjects consumed a Thai diet containing 3 meals ( 8373.6 kJ/day ) for 12 weeks , prepared by the Nutritional Unit at Srinagarind Hospital . The diet contained 65 % carbohydrates , 15 % protein , and 20 % fat . Body weight , BMI , body composition , resting energy expenditure , and substrate oxidation were measured at baseline , and during weeks 4 , 8 , and 12 of the study . Serum levels of leptin and urine VMA were measured at baseline and during the 12th week . Differences over time and between the treatments ( green tea or placebo ) over time were determined using two-factor ANOVA with repeated measures . In comparing the two groups , differences in weight loss were 2.70 , 5.10 , and 3.3 kg during the 4th , 8th , and 12th weeks of the study , respectively . At the 8th and 12th weeks of the study , body weight loss was significantly different ( P < 0.05 ) . At the 8th week , the difference in resting energy expenditure was 183.38 kJ/day ( P < 0.001 ) , the difference in the respiratory quotient was 0.02 ( P < 0.05 ) , and no significant differences existed in satiety score , food intake , or physical activity . Urine VMA was significantly different in the 12th week of the study ( P < 0.05 ) . We conclude that green tea can reduce body weight in obese Thai subjects by increasing energy expenditure and fat oxidation This study evaluated the influence of a green tea catechin beverage on body composition and fat distribution in overweight and obese adults  during exercise-induced weight loss . Participants ( n = 132 with 107 completers ) were r and omly assigned to receive a beverage containing approximately 625 mg of catechins with 39 mg caffeine or a control beverage ( 39 mg caffeine , no catechins ) for 12 wk . Participants were asked to maintain constant energy intake and engage in > or=180 min/wk moderate intensity exercise , including > or=3 supervised sessions per week . Body composition ( dual X-ray absorptiometry ) , abdominal fat areas ( computed tomography ) , and clinical laboratory tests were measured at baseline and wk 12 . There was a trend ( P = 0.079 ) toward greater loss of body weight in the catechin group compared with the control group ; least squares mean ( 95 % CI ) changes , adjusted for baseline value , age , and sex , were -2.2 ( -3.1 , -1.3 ) and -1.0 ( -1.9 , -0.1 ) kg , respectively . Percentage changes in fat mass did not differ between the catechin [ 5.2 ( -7.0 , -3.4 ) ] and control groups [ -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 ( TG ) [ -11.2 ( -18.8 , -3.6 ) vs. 1.9 ( -5.9 , 9.7 ) ; P = 0.023 ] were greater in the catechin group . These findings suggest that green tea catechin consumption enhances exercise-induced changes in abdominal fat and serum TG Objectives : To study the effects of green tea on body weight , and biochemical and hormonal profiles in obese Chinese women with polycystic ovary syndrome ( PCOS ) . Methods : Thirty-four obese Chinese women with PCOS were r and omized into either treatment with green tea capsules or placebo for 3 months . The anthropomentric measurements , and biochemical and hormonal profiles before and after treatment in each group were compared . Results : The body weight of the green tea group decreased by a nonsignificant 2.4 % after treatment ; whereas the body weight , body mass index ( BMI ) , and body fat content of the control group were significantly higher after 3 months . There were no differences in any of the hormone levels measured in either group . The biochemical profiles of the two groups were also similar except that there was a small but significant rise in the triglyceride level in the green tea group . Fewer patients in the green tea group remained amenorrhoeic , but this was not significantly different from the control group . Conclusions : Green tea supplementation did not significantly reduce body weight in obese women with PCOS , nor did it alter the glucose or lipid metabolism The present study was conducted to investigate whether green tea may improve weight maintenance by preventing or limiting weight regain after weight loss of 5 to 10 % in overweight and moderately obese subjects . The study had a r and omised , parallel , placebo-controlled design . A total of 104 overweight and moderately obese male and female subjects ( age 18 - 60 years ; BMI 25 - 35 kg/m(2 ) ) participated . The study consisted of a very-low-energy diet intervention ( VLED ; 2.1 MJ/d ) of 4 weeks followed by a weight-maintenance period of 13 weeks in which the subjects received green tea or placebo . The green tea contained caffeine ( 104 mg/d ) and catechins ( 573 mg/d , of which 323 mg was epigallocatechin gallate ) . Subjects lost 6.4 ( sd 1.9 ) kg or 7.5 ( sd 2.2 ) % of their original body weight during the VLED ( P<0.001 ) . Body-weight regain was not significantly different between the green tea and the placebo group ( 30.5 ( sd 61.8 ) % and 19.7 ( sd 56.9 ) % , respectively ) . In the green tea treatment , habitual high caffeine consumption was associated with a higher weight regain compared with habitual low caffeine consumption ( 39 ( sd 17 ) and 16 ( sd 11 ) % , respectively ; P<0.05 ) . We conclude that weight maintenance after 7.5 % body-weight loss was not affected by green tea treatment and that habitual caffeine consumption affected weight maintenance in the green tea treatment Regular consumption of green tea may be cardioprotective . In the present study we investigated the health effects of dietary supplementation with green tea catechins and the potential modifying effect of the catechol-O-methyltransferase ( COMT ) Val/Met genotype . Subjects ( sedentary males , aged 40 - 69 years , with BMI ≥ 28 and ≤ 38 kg/m(2 ) ) were r and omly assigned to consume decaffeinated green tea extract ( DGT ; 530 mg containing about 400 mg total catechins/capsule , twice daily ) and placebo in a complete cross-over design . Ambulatory blood pressure and biomarkers of metabolic function ( cholesterol , TAG , glucose and insulin ) were measured at weeks 0 and 6 . Although a marked increase in the concentration of plasma epigallocatechin gallate ( EGCG ) , urinary epigallocatechin ( EGC ) and urinary 4'-O-methyl EGC was found after DGT treatment , no effect on blood pressure or biomarkers of metabolic function was observed . However , a period × treatment interaction ( P < 0·05 ) was detected for body-weight change . Despite a similar increase in estimated energy intake during intervention period 1 , body weight decreased by 0·64 ( sd 2·2 ) kg and increased by 0·53 ( sd 1·9 ) kg in the DGT and placebo groups , respectively ( P = 0·025 ) , suggesting a protective effect of green tea catechins on weight gain . Additionally , the COMT Val/Met genotype influenced urinary accumulation of EGC and 4'-O-methyl EGC ( P < 0·01 ) . Mean concentrations were lower in individuals homozygous for the high-activity G-allele , possibly reflecting increased metabolic flux and a more rapid conversion to downstream metabolic species , compared with individuals carrying at least one copy of the low-activity A-allele . Additional studies are needed to confirm these findings and further explore the modifying effect of genotype 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 r and omized , 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/m(2 ) and who had not received any other weight control maneuvers within the last 3 months completed this study . The subjects were r and omly 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 h and , 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 OBJECTIVE The body fat reducing effect and reduction of risks for cardiovascular disease by a green tea extract ( GTE ) high in catechins was investigated in humans with typical lifestyles . RESEARCH METHODS AND PROCEDURES Japanese women and men with visceral fat-type obesity were recruited for the trial . After a 2-week diet run-in period , a 12-week double-blind parallel multicenter trial was performed , in which the subjects ingested green tea containing 583 mg of catechins ( catechin group ) or 96 mg of catechins ( control group ) per day . R and omization was stratified by gender and body mass index at each medical institution . The subjects were instructed to maintain their usual dietary intake and normal physical activity . RESULTS Data were analyzed using per- protocol sample s of 240 subjects ( catechin  group ; n = 123 , control group ; n = 117 ) . Decreases in body weight , body mass index , body fat ratio , body fat mass , waist circumference , hip circumference , visceral fat area , and subcutaneous fat area were found to be greater in the catechin group than in the control group . A greater decrease in systolic blood pressure ( SBP ) was found in the catechin group compared with the control group for subjects whose initial SBP was 130 mm Hg or higher . Low-density lipoprotein ( LDL ) cholesterol was also decreased to a greater extent in the catechin group . No adverse effect was found . DISCUSSION The continuous ingestion of a GTE high in catechins led to a reduction in body fat , SBP , and LDL cholesterol , suggesting that the ingestion of such an extract contributes to a decrease in obesity and cardiovascular disease risks BACKGROUND Green tea extract ( GTE ) consumption has been linked to favorable changes in adiposity and bone mineral density ( BMD ) , although it is unknown if these effects are due to green tea catechins or caffeine . The catechol-O-methyltransferase ( COMT ) genotype may also modify these associations . OBJECTIVE We examined the impact of decaffeinated GTE on body composition ( using dual-energy X-ray absorptiometry ) and obesity-associated hormones . METHODS The Minnesota Green Tea Trial was a 12-mo r and omized , double-blind , placebo-controlled clinical trial in 937 postmenopausal women ( aged 50 - 70 y ) assigned to receive either GTE containing 843 mg (-)-epigallocatechin-3-gallate or placebo . This sub study was conducted in 121 overweight/obese participants [ body mass index ( BMI ) ( kg/m(2 ) ) ≥25.0 ] . RESULTS There were no differences in changes in BMI ( -0.13 ± 0.11 compared with -0.05 ± 0.11 ; P = 0.61 ) , total fat mass ( -0.30 ± 0.16 compared with -0.12 ± 0.15 kg ; P = 0.40 ) , percentage of body fat ( -0.15 % ± 0.17 % compared with -0.15 % ± 0.16 % ; P = 0.99 ) , or BMD ( -0.006 ± 0.002 compared with -0.003 ± 0.002 g/cm(2 ) ; P = 0.49 ) over 12 mo between women taking GTE ( n = 61 ) and those taking a placebo ( n = 60 ) . Interactions were observed between treatment and time for gynoid percentage of fat ( % fat ) and tissue % fat . Gynoid % fat increased from baseline to month 12 in the placebo group as baseline BMI increased and decreased over time as baseline BMI increased in the GTE group ( P-interaction = 0.02 ) . Tissue % fat increased from baseline to month 12 in the placebo group as baseline BMI increased . In the GTE  group , tissue % fat decreased during the intervention as baseline BMI increased ( P-interaction = 0.04 ) . No changes were seen in circulating leptin , ghrelin , adiponectin , or insulin concentrations . COMT genotype did not modify the effect of GTE on any variable . CONCLUSIONS Decaffeinated GTE was not associated with overall reductions in adiposity or improvements in BMD in overweight/obese postmenopausal women . However , GTE may be beneficial for reduction in tissue and gynoid % fat in individuals with higher BMI . This clinical trial was registered at www . clinical trials.gov as NCT00917735
target: Research has been very varied , however , daily consumption of green tea with doses of EGCG between 100 and 460 mg/day has shown greater effectiveness on body fat and body weight reduction in intervention periods of 12 weeks or more .
  In addition , the use of caffeine doses between 80 and 300 mg/day has been shown to be an important factor for this effects , when the participants did not have a high caffeine intake ( > 300 mg/day ) prior to the intervention
background: The prevalence and incidence of overweight and obesity worldwide continues to increase , as well as diseases related to these conditions .
  This is attributed to an increase in energy intake and a decrease in energy expenditure .
  Consumption of green tea has been linked to a reduction in body fat and body weight .
  However , research on green tea has been very diverse .
  This review assesses the investigations that have been made with green tea and its epigallocatechin gallato ( EGCG ) content , evaluating its effect on body fat and body weight in humans .