Table 1.

Studies on the effects of green tea catechins (GTC) supplementation on resting metabolic rate.

First Author, Year	Study Design	Compound	Treatment and Daily Dose	Placebo or Other Treatments	Subjects	Duration	Parallel Prescriptions	Main Outcomes/Results	Method	Dietary Information
Chronic intake
Quinhoneiro, 2018	Longitudinal prospective interventional Study.	Decaffeinated green tea extract capsules (Solaray®).	2 capsules daily for a total of 1009 mg of green tea leaf extract, with 450 mg of epigallocatechin gallate (EGCG), 85.7 mg of epicatechin gallate (ECG), and 5.9 mg of caffeine per day.	/	21 women with severe obesity (grade III).	8 weeks	Not to change the dietary pattern or the level of physical activity. Fast and no physical exercise or caffeine-rich beverages (coffee, black tea, or energy drink) 24 h before the assessment.	Compared to baseline values, resting metabolic rate (RMR) and substrate oxidation did not change significantly after 8 weeks of supplementation with green tea.	Indirect calorimetry QUARK-RMR device (COSMED, Rome, Italy). The QUARK-RMR device was automatically calibrated with known gas concentrations before all the assessments.	Usual diet. Macronutrient composition not specified.
Mielgo-Ayuso, 2014	Randomized, double-blind, and parallel Design.	TEAVIGOTM DSM Nutritional Products.	EGCG (300 mg EGCG/day) comprising >97% of pure EGCG.	Placebo: 300 mg of lactose/day.	83 obese premenopausal women.	12 weeks.	Not to consume any other beverage containing catechins or caffeine during the intervention program. 12-week energy-restricted diet.	There were no significant interaction effects between time and treatment group (EGCG or control) on energy and substrate metabolism outcomes.	Indirect calorimetry (Vmax; SensorMedics).	55% carbohydrates, 30% lipids, and 15% proteins.
Cardoso, 2012	Double-blinded and placebo-controlled.	Sanavita Industry.	Group 1: 20 g of green tea (with 40 mg of caffeine), daily diluted in 200 ml of ice water. Group 3: green tea plus resistance training.	Group 2: 20 g of placebo. Group 4: placebo plus resistance training.	36 overweight or obese women.	8 weeks.	A base diet started 4 weeks prior to the green tea protocol was continued for all the duration of the treatment.	The RMR decreased significantly in groups 1 and 2 but increased significantly in groups 3 and 4 (p < 0.05). In group 1, the RMR for body mass showed no change, while in group 2, there was a measurable but not significant decline. In groups 3 and 4, the RMR for body mass increased significantly, and it was highest in group 3.	Indirect calorimetry with a pneumotachograph connected to a gas analyzer (Aerosport VO2000; Medical Graphics Corporation).	Usual diet. Macronutrient composition not specified.
Auvichayapat, 2008	Randomized controlled trial.	Herbal One®.	3 capsules daily. Each capsules contained 250 mg of green tea leaf extract, 0.24 mg of gallic acid, 4.09 mg of catechin, 28.86 mg of caffeine, 33.58 mg of EGCG, and 9.28 mg of epicatechin gallate.	Placebo: cellulose capsule.	60 obese subjects (42 females and 18 males).	12 weeks.	Thai diet (65% carbohydrates, 15% protein, and 20% fat).	Green tea increased energy expenditure by the 8th week of the study; specifically, the RMR was 372 kJ/day higher than at baseline. The increase in RMR was approximately one-third of moderate exercise. The reduction in respiratory quotient (RQ) during treatment with the green tea extract suggests that fat oxidation was higher.	The bag technique of indirect calorimetry.	Thai diet containing 65% carbohydrates, 15% protein, and 20% fat.
Acute intake
Lonac, 2011	Within-subjects and repeated-measures design.	TEAVIGOTM DSM Nutritional Products	135 mg of EGCG/capsule 3 times daily, for a total of 405 mg of EGCG/day. 3 capsules/day with each meal. The final capsule was consumed 2 h before metabolic testing.	135 mg of organic cornmeal/capsule, 3 times daily.	16 healthy adults (9 males and 7 females)	2 days of test. separated by a minimum of 7 days.	Test at 12-h fast, 2-h abstention from water, and 24-h abstention from exercise.	Short-term consumption did not increase RMR or the thermic effect of feeding.	Custom-built, ventilated-hood, indirect calorimetry system (Nighthawk Design, Boulder, CO).	At completion of test, liquid mixed meal (57% carbohydrate, 28% fat, and 15% protein).
Belza, 2009	Crossover, randomized, placebo-controlled, and double-blind study.	Alpine Health Products.	Group 1: tablets of 500 mg of green tea extract (where of 125 mg of catechins).	Group 2: 400 mg of tyrosine. Group 3: 50 mg of caffeine. Group 4: placebo, microcrystalline cellulose.	12 healthy, normal weight men.	4 h measurement following ingestion.	Ad libitum energy intake. Each treatment was separated by a >3-day washout.	Caffeine induced a thermogenic response of 6% above baseline value (72 ± 25 kJ per 4 h) compared to placebo (p < 0.0001). The thermogenic responses to GTE and tyrosine were not significantly different from placebo. Tyrosine tended to increase 4-h respiratory quotient by 1% compared to placebo (0.01 ± 0.005, p < 0.05).	Indirect calorimetry using a ventilated hood system.	At completion of the respiratory measurements, the subjects were given an ad libitum brunch 4 h after the intake of one of the treatment compounds. The ad libitum meal was a 1329 g pasta salad brunch (610 kJ 100 g−1, protein: 15 energy (E)%, carbohydrates: 55 E% and fat: 30%).
Roberts, 2005	Double-blind, placebo controlled, and crossover study.	Not specified.	The supplement contained water-soluble extracts, including 600 mg of black tea extract providing 60% polyphenols and 20% caffeine, 422 mg of guarana extract providing 36% caffeine, 100 mg of ginger extract providing 5% gingerols, 5 mg of dill weed extract, 150 mg of rutin (quercetin-3-O-glucose- rhamnose), and 50 mg of vitamin C. Each capsule contained 725 mg for a total of 1450 mg in two capsules.		16 healthy subjects (7 males and 9 females).		Subjects had no caffeine for 48 h, no exercise for 24 h, and no food for 12 h before each visit.	The area under curve (AUC) for metabolic rate increased significantly after the herbal supplement by 77.19 ± 120.10 kcal/24 h (p < 0.02) compared to placebo (1 kcal is equivalent to 4.184 kJ) (Figure 1). The rise in metabolic rate peaked at one hour, with no statistical significance between active and placebo arms at two hours.	Indirect calorimetry using a ventilated hood system (DeltaTrac II metabolic monitor; Datex Inc.; Helsinki, Finland).	Usual diet. Macronutrient composition not specified.

Abbreviations: RMR, resting metabolic rate; GTE, green tea extract.