The Effects of Epigallocatechin-3-Gallate on Thermogenesis and Fat Oxidation in Obese Men: A Pilot Study Body weight loss and weight maintenance in relation to habitual caffeine intake and green tea supplementation. Green tea catechin plus caffeine supplementation to a high-protein diet has no additional effect on body weight maintenance after weight loss. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Epigallocatechin-3-gallate and postprandial fat oxidation in overweight/obese male volunteers: a pilot study Effectiveness of green tea on weight reduction in obese Thais: A randomized, controlled trial Effect of green tea on resting energy expenditure and substrate oxidation during weight loss in overweight females. Effects of encapsulated green tea and Guarana extracts containing a mixture of epigallocatechin-3-gallate and caffeine on 24 h energy expenditure and fat oxidation in men. 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.
Objectives : The development of obesity is characterized by an increase in adipose tissue mass and by concomitant and profound changes in almost all organ functions leading to diseases such as hypertension , diabetes mellitus and coronary heart disease . Recent data from human studies indicate that the consumption of green tea and green tea extracts may help reduce body weight , mainly body fat , by increasing postpr and ial thermogenesis and fat oxidation . However , human studies investigating the metabolic effects of the most predominant tea catechin , EGCG , alone are absent . Methods : In a r and omized double blind , placebo-controlled , cross-over pilot study , six overweight men were given 300 mg EGCG/d for 2d . Fasting and postpr and ial changes in energy expenditure ( EE ) and substrate oxidation were assessed . Results : Resting EE did not differ significantly between EGCG and placebo treatments , although during the first postpr and ial monitoring phase , respiratory quotient ( RQ ) values were significantly lower with EGCG compared to the placebo . Conclusions : These findings suggest that EGCG alone has the potential to increase fat oxidation in men and may thereby contribute to the anti-obesity effects of green tea . However , more studies with a greater sample size and a broader range of age and BMI are needed to define the optimum dose OBJECTIVE Investigation of the effect of a green tea-caffeine mixture on weight maintenance after body weight loss in moderately obese subjects in relation to habitual caffeine intake . RESEARCH METHODS AND PROCEDURES A r and omized placebo-controlled double blind parallel trial in 76 overweight and moderately obese subjects , ( BMI , 27.5 + /- 2.7 kg/m2 ) matched for sex , age , BMI , height , body mass , and habitual caffeine intake was conducted . A very low energy diet intervention during 4 weeks was followed by 3 months of weight maintenance ( WM ) ; during the WM period , the subjects received a green tea-caffeine mixture ( 270 mg epigallocatechin gallate + 150 mg caffeine per day ) or placebo . RESULTS Subjects lost 5.9 + /-1.8 ( SD ) kg ( 7.0 + /- 2.1 % ) of body weight ( p < 0.001 ) . At baseline , satiety was positively , and in women , leptin was inversely , related to subjects ' habitual caffeine consumption ( p < 0.01 ) . High caffeine consumers reduced weight , fat mass , and waist circumference more than low caffeine consumers ; resting energy expenditure was reduced less and respiratory quotient was reduced more during weight loss ( p < 0.01 ) . In the low caffeine consumers , during WM , green tea still reduced body weight , waist , respiratory quotient and body fat , whereas resting energy expenditure was increased compared with a restoration of these variables with placebo ( p < 0.01 ) . In the high caffeine consumers , no effects of the green tea-caffeine mixture were observed during WM . DISCUSSION High caffeine intake was associated with weight loss through thermogenesis and fat oxidation and with suppressed leptin in women . In habitual low caffeine consumers , the green tea-caffeine mixture improved WM , partly through thermogenesis and fat oxidation BACKGROUND Green tea ( epigallocatechin gallate + caffeine ) and protein each were shown to improve body weight maintenance after weight loss . OBJECTIVE We investigated the effect of a green tea-caffeine mixture added to a high-protein ( HP ) diet on weight maintenance ( WM ) after body weight loss in moderately obese subjects . DESIGN A r and omized , placebo-controlled , double-blind parallel trial was conducted in 80 overweight and moderately obese subjects [ age ( mean + /- SD ) : 44 + /- 2 y ; body mass index ( BMI ; in kg/m(2 ) ) : 29.6 + /- 2.0 ] matched for sex , age , BMI , height , body mass , and with a habitually low caffeine intake . A very-low-energy diet intervention during 4 wk was followed by 3 mo of WM ; during the WM period , the subjects received a green tea-caffeine mixture ( 270 mg epigallocatechin gallate + 150 mg caffeine/d ) or placebo , both in addition to an adequate protein ( AP ) diet ( 50 - 60 g protein/d ) or an HP diet ( 100 - 120 g protein/d ) . RESULTS Subjects lost 7.0 + /- 1.6 kg , or 8.2 + /- 2.0 % , body weight ( P < 0.001 ) . During the WM phase , WM , resting energy expenditure , and fat-free mass ( FFM ) increased relatively in both the HP groups and in the AP + green tea-caffeine mixture group ( P < 0.05 ) , whereas respiratory quotient and body fat mass decreased , all compared with the AP + placebo group . Satiety increased only in both HP groups ( P < 0.05 ) . The green tea-caffeine mixture was only effective with the AP diet . CONCLUSION The green tea-caffeine mixture , as well as the HP diet , improved WM independently through thermogenesis , fat oxidation , sparing FFM , and , for the HP diet , satiety ; a possible synergistic effect failed to appear 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 Objectives : Drinking green tea is associated with many health benefits , including increased fat oxidation . We tested the hypothesis that epigallocatechin-3-gallate ( EGCG ) , the main green tea catechin , increases  fat oxidation in obese men . Methods : Ten healthy overweight/obese males ( body mass index 31.3±0.8 kg/m2 ) were studied in a r and omized , placebo-controlled , double-blind crossover trial . Study supplements were low EGCG ( 300 mg ) , high EGCG ( 600 mg ) , caffeine ( 200 mg ) , EGCG/caffeine ( 300 mg/200 mg ) or placebo and were taken orally for 3 days . At the third day of supplementation , O2 consumption and CO2 production was measured by indirect calorimetry to assess energy expenditure and fat oxidation over 4 h each after overnight fasting and after a st and ardized test meal . Results : Energy expenditure was not affected by any supplementation , neither after overnight fasting nor after the test meal . During the first 2 h after overnight fasting , fat oxidation increased by 7.7 ( not significant , NS ) , 15.2 ( NS ) , 26.3 ( P<0.05 vs placebo ) and 35.4 % ( P<0.01 vs placebo and low EGCG ) , for low EGCG , high EGCG , caffeine and EGCG/caffeine , respectively . During the first 2 h after the meal , the mean increase in fat oxidation was 33.3 ( P<0.05 vs placebo ) , 20.2 ( NS ) , 34.5 ( P<0.05 vs placebo ) and 49.4 % ( P<0.05 vs placebo ) for low EGCG , high EGCG , caffeine and EGCG/caffeine , respectively . Conclusions : Low EGCG increases postpr and ial fat oxidation  in obese men and this to the same extent as 200 mg caffeine , whereas high EGCG does not exert this effect . Fasting fat oxidation is increased only by caffeine ( with or without EGCG ) . There is no synergism of low EGCG and 200 mg caffeine . Energy expenditure is not affected by EGCG 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 We assessed the effect of ingestion of green tea ( GT ) extract along with a low-energy diet ( LED ) on resting energy expenditure ( REE ) , substrate oxidation and body weight as GT has been shown to increase energy expenditure and fat oxidation in the short term in both animals and people . Forty-six overweight women ( BMI 27.6 ( sd 1.8 ) kg/m2 ) were fed in energy balance from day 1 to day 3 , followed by a LED with GT ( 1125 mg tea catechins + 225 mg caffeine/d ) or placebo ( PLAC ) from day 4 to day 87 . Caffeine intake was st and ardised to 300 mg/d . Energy expenditure was measured on days 4 and 32 . Reductions in weight ( 4.19 ( sd 2.0 ) kg PLAC , 4.21 ( sd 2.7 ) kg GT ) , BMI , waist : hip ratio , fat mass and fat-free mass were not statistically different between treatments . REE as a function of fat-free mass and fat mass was significantly reduced over 32 d in the PLAC group ( P<0.05 ) but not in the GT group . Dietary restraint increased over time ( P<0.001 ) in both groups , whereas disinhibition and general hunger decreased ( P<0.05 ) . The GT group became more hungry over time and less thirsty , and showed increased prospect i ve food consumption compared with PLAC ( P<0.05 ) . Taken together , the ingestion of GT along with a LED had no additional benefit for any measures of body weight or body composition . Although the decrease in REE as a function of fat-free mass and fat mass was not significant with GT treatment , whereas it was with PLAC treatment , no significant effect of treatment over time was seen , suggesting that a robust limitation of REE reduction during a LED was not achieved by GT It has been reported that green tea has a thermogenic effect , due to its caffeine content and probably also to the catechin , epigallocatechin-3-gallate ( EGCG ) . The main aim of the present study was to compare the effect of a mixture of green tea and Guarana extracts containing a fixed dose of caffeine and variable doses of EGCG on 24 h energy expenditure and fat oxidation .  Fourteen subjects took part to this r and omized , placebo-controlled , double-blind , cross-over study . Each subject was tested five times in a metabolic chamber to measure 24 h energy expenditure , substrate oxidation and blood pressure . During each stay , the subjects ingested a capsule of placebo or capsules containing 200 mg caffeine and a variable dose of EGCG ( 90 , 200 , 300 or 400 mg ) three times daily , 30 min before st and ardized meals . Twenty-four hour energy expenditure increased significantly by about 750 kJ with all EGCG-caffeine mixtures compared with placebo . No effect of the EGCG-caffeine mixture was observed for lipid oxidation . Systolic and diastolic blood pressure increased by about 7 and 5 mmHg , respectively , with the EGCG-caffeine mixtures compared with placebo . This increase was significant only for 24 h diastolic blood pressure . The main finding of the study was the increase in 24 h energy expenditure with the EGCG-caffeine mixtures . However , this increase was similar with all doses of EGCG in the mixtures 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
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
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 .