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 consisted of a very-low-energy diet intervention (VLED; 2·1MJ/d) of 4 weeks followed by a weight-maintenance period of 13 weeks in which the subjects received green tea or placebo.

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.

Subsequently, within the low or high habitual caffeine consumption groups, subjects were further stratified according to the characteristics mentioned above and randomized to a prospective green tea-caffeine mixture treatment group and a placebo group for the weight maintenance phase (Table 1 ). During this weight maintenance phase, the subjects received a green tea-caffeine mixture [45 mg epigallocatechin gallate + 25 mg caffeine + 380 mg placebo (vegetable oil)/capsule; 6 capsules/d; 2 capsules before each meal] or placebo [450 mg placebo (vegetable oil)/capsule; 6 capsules/d; 2 capsules before each meal]. The dosage of epigallocatechin gallate was the same as used by Dulloo et al.(19 ); the dosage of caffeine was lower to avoid a dosage >1000 mg/d, because of the habitually high caffeine consumption of 100 to 1000 mg/d in The Netherlands (23 ). Table 1. . Baseline characteristics of the subjects (n = 76) divided over habitual high and low caffeine intake groups and prospective treatment groups (green tea vs. placebo) Green tea (n = 38) Placebo (n = 38) Low caffeine (n = 19) High caffeine (n = 19) Low caffeine (n = 19) High caffeine (n = 19) BM (kg) 85.1 ± 9.5 85.0 ± 8.5 85.1 ± 9.6 85.0 ± 8.3 Height (m) 1.70 ± 0.12 1.70 ± 0.11 1.70 ± 0.10 1.70 ± 0.12 BMI (kg/m2 ) 29.6 ± 2.6 29.5 ± 2.4 29.6 ± 2.7 29.5 ± 2.2 Waist (cm) 94.2 ± 7.7 94.0 ± 7.1 94.0 ± 7.3 94.0 ± 7.0 FFM (kg) 53.4 ± 9.1 53.3 ± 9.2 53.4 ± 9.2 53.3 ± 9.0 FM (kg) 31.7 ± 6.9 31.7 ± 5.8 31.7 ± 7.0 31.7 ± 5.6 Percent body fat 37.3 ± 5.4 37.3 ± 4.7 37.3 ± 5.1 37.7 ± 4.9 F1 7.0 ± 2.7 7.5 ± 3.1 7.0 ± 2.8 7.4 ± 3.3 F2 5.7 ± 2.1 6.0 ± 2.2 5.6 ± 2.4 6.1 ± 2.3 F3 4.9 ± 3.0 4.9 ± 3.1 4.9 ± 3.1 4.9 ± 3.2 HP 16.1 ± 3.7 16.3 ± 3.2 16.2 ± 3.6 16.2 ± 3.1 Hunger (mm VAS) 38.2 ± 24.0 32.5 ± 26.2 37.6 ± 25.0 32.7 ± 25.2 Satiety (mm VAS) 25.9 ± 20.2 35.3 ± 21.8* 26.9 ± 21.4 36.3 ± 22.9* REE (MJ/d) 6.9 ± 0.9 7.0 ± 1.0 6.9 ± 1.0 7.1 ± 1.1 RQ 0.84 ± 0.03 0.83 ± 0.04 0.84 ± 0.02 0.83 ± 0.03 PAL 1.6 ± 0.1 1.6 ± 0.1 1.6 ± 0.1 1.6 ± 0.1 TEE (MJ/d) 11.0 ± 1.3 11.4 ± 1.5 11.0 ± 1.2 11.4 ± 1.6 Glucose (mM/L) 5.5 ± 0.8 5.6 ± 0.5 5.6 ± 0.7 5.7 ± 0.6 Insulin (mUnits/mL) 10.4 ± 4.3 10.5 ± 3.6 10.5 ± 5.3 10.6 ± 4.6 BHB (mM/L) 250.0 ± 78.6 264.4 ± 103.7 256.0 ± 84.7 266.4 ± 93.2 Glycerol (mM/L) 96.4 ± 34.0 99.2 ± 38.6 97.4 ± 35.0 98.2 ± 39.7 FFA (mM/L) 324.1 ± 131.0 322.9 ± 122.5 323.7 ± 132.0 322.1 ± 120.8 Triglycerides (mM/L) 1286.9 ± 633.2 1262.9 ± 626.1 1363.9 ± 605.9 1313.9 ± 600.9 Leptin (ng/L) 26.3 ± 8.6 19.0 ± 7.9* 26.0 ± 6.8 18.8 ± 6.9* Values are mean ± SD. The blood parameters glucose, insulin, triacylglycerol, and leptin decreased during weight loss, whereas glycerol, FFA, and β-hydroxybutyrate increased, without differences in changes between prospective treatment groups (Table 2 ). Weight Maintenance During the weight maintenance period, the percentage of body weight regained was significantly smaller in the low caffeine intake group that received the green tea-caffeine mixture (−11.1 ± 24.3%), and, in fact, the group continued to lose weight, compared with the low caffeine group receiving placebo (40.8 ± 28.9%; time × treatment interaction; p < 0.01). This was also the case when the low-caffeine intake group that received the green tea-caffeine mixture was compared with the high caffeine group receiving the green tea-caffeine mixture, who regained 24.4 ± 18.7% of the body weight lost (time × treatment interaction; p < 0.01). This also implied a smaller increase in body mass, BMI, waist circumference, and FM over time in the low caffeine intake group that received the green tea-caffeine mixture.

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. Introduction The prevalence of overweight and obesity is increasing worldwide, both in developing and developed countries [1]. Obesity is associated with an increased risk of chronic diseases, such as type 2 diabetes and cardiovascular disease, including hypertension [1]. In Asia, overweight is defined as body mass index (BMI) of 23–24.9kg/m2 ; obesity grade I is 25–29.9kg/m2 and obesity grade II is > 30kg/m2 [2]. Currently, the effective treatment of obesity includes a reduced-energy intake, increased physical activity and exercise, behavior modification, pharmacotherapy, and surgery [1]. The maximal success rate of these treatments; however, is only 21%, and the most popular method for weight loss is pharmacotherapy [3]. Green tea is a herbal that contains two major active ingredients: 1) catechin polyphenol, which inhibits the action of catechol-o -methyl-transferase (COMT), resulting in a prolonged action of catecholamines and 2) caffeine, which inhibits the phosphodiesterase-induced degradation of intracellular cyclic AMP (cAMP) leading to an increase in norepinephrine release [4]; the net result, therefore, is an elevated cellular concentration of cAMP, a critical intracellular mediator for the action of catecholamines on thermogenesis [4], [5], [6], [7], [8]. Furthermore, catecholamines in the brain may play a major role in satiety [18], [26]. Both catechin polyphenols and caffeine may be effective promoters of thermogenesis and fat oxidation, resulting in the reduction of body weight in Caucasians, Chinese, and Japanese [4], [5], [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], [25]. Lipolytic activities between ethnic groups are different from non-esterified fatty acids [27], [28]. Also, the components of native foods, in warm climates contain much more fat (35–40%) than in tropical areas (15–30%) [29], [30]. Thus, the result of green tea function in Caucasians, Chinese, and Japanese may not be the same as in Thais or in inhabitants of tropical areas.

We searched for randomized controlled trials (RCTs) that evaluated women with PCOS who received green tea compared with placebo in electronic databases: MEDLINE via PubMed, EMBASE via Elsevier, Cochrane Library , LILACS via BVS, and Web of Science using the terms: “polycystic ovary syndrome,” “green tea,” “Camellia sinensis,” “epigallocatechin gallate.” The outcomes listed in the study protocol were body weight, fasting insulin, body mass index , body fat percentage, daily caloric intake , waist circumference, hip circumference , and waist/hip ratio. We found a significantly lower body weight (kg) for green tea group (mean difference, -2.80; 95% confidence interval, -5.25 to -0.35; P = .03; I ² = 0%; 4 studies, 169 participants, very low-quality evidence). Green tea has potential positive effects for the reduction of weight, and future studies will be needed to confirm the estimated effect size; we reasonably expect this to be an option of adjuvant treatment in PCOS clinical management.

The Third National Health and Nutrition Examination Survey, 1988–1994. Diabetes Care 1998; 21 : 475–476. Article Google Scholar Tuomilehto J, Hu G, Bidel S, Lindstrom J, Jousilahti P . Coffee consumption and risk of type 2 diabetes mellitus among middle-aged Finnish men and women. J Intern Med 2004; 255 : 89–95. Article CAS Google Scholar van Dam RM, Feskens EJ . Coffee consumption and risk of type 2 diabetes mellitus.

Abstract The effect of ingestion of green tea (GT) extract along with a low-energy diet (LED) on health-related blood parameters, and the relationships among changes in metabolic parameters and phases of weight loss were assessed. The LED-period consisted of a phase 1 of 4 weeks (days 4–32) followed by a phase 2 of 8 weeks (days 32–87). Body composition and fasting blood samples were determined on days 4, 32 and 87.

Am J Physiol Regul Integr Comp Physiol 2007; 292 : R77–R85. Article CAS PubMed Google Scholar Dulloo AG, Duret C, Rohrer D, Girardier L, Mensi N, Fathi M et al . Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr 1999; 70 : 1040–1045. Article CAS PubMed Google Scholar Berube-Parent S, Pelletier C, Dore J, Tremblay A . 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.

Meta‐analysis of six studies conducted outside Japan showed a mean difference (MD) in weight loss of ‐0.04 kg (95% CI ‐0.5 to 0.4; P = 0.88; I2 = 18%; 532 participants). The eight studies conducted in Japan were not similar enough to allow pooling of results and MD in weight loss ranged from ‐0.2 kg to ‐3.5 kg (1030 participants) in favour of green tea preparations. Meta‐analysis of five studies conducted outside Japan and measuring waist circumference reported a MD of ‐0.2 cm (95% CI ‐1.4 to 0.9; P = 0.70; I2 = 58%; 404 participants). Differences among the eight studies conducted in Japan did not allow pooling of results and showed effects on waist circumference ranging from a gain of 1 cm to a loss of 3.3 cm (1030 participants). Meta‐analysis for three weight loss studies, conducted outside Japan, with waist‐to‐hip ratio data (144 participants) yielded no significant change (MD 0; 95% CI ‐0.02 to 0.01). Analysis of two studies conducted to determine if green tea could help to maintain weight after a period of weight loss (184 participants) showed a change in weight loss of 0.6 to ‐1.6 kg, a change in BMI from 0.2 to ‐0.5 kg/m2 and a change in waist circumference from 0.3 to ‐1.7 cm.