Table 2.

Studies on the effects of GTC supplementation on total energy expenditure.

First Author, Year	Study Design	Compound	Treatment and Daily Dose	Placebo or Other Treatments	Subjects	Duration	Parallel Prescription	Main Outcomes/Results	Method	Dietary Information
Chronic intake
Mahler, 2015	Randomized, double-blind, placebo-controlled, and crossover study.	TeaCare; Limmer Nutraceuticals BV.	600 mg of EGCG/day. EGCG (2 capsules × 150 mg) were taken twice daily. Metabolism was measured at rest (protocol 1) and during exercise (protocol 2).	Placebo: starch.	18 subjects with multiple sclerosis (8 males and 10 females).	12 and 4 week washout periods.	Not specified. Metabolic evaluations after a 12-h overnight fast and intake of 300 mg of EGCG in the morning.	PROTOCOL 1: Fasting energy expenditure (EE) did not differ between placebo and EGCG. PROTOCOL 2: Total increase in EE was lower in men (p = 0.01) and women (non-significant) receiving EGCG compared with placebo.	Canopy calorimeter (Deltatrac II; Datex Ohmeda).	50%, 35%, and 15% of energy from carbohydrates, fats, and proteins.
Brown, 2009	Double-blind, randomized, and parallel design study.	TEAVIGO™; DSM), comprising >97% pure EGCG.	800 mg of EGCG/day 2 capsules/day daily with food, one 400 mg capsule in the morning and another in the evening.	Placebo: 800 mg of lactose/day.	88 overweight or obese men.	8 weeks.	To avoid exercise and alcohol consumption for the 24 h before each measurement. Test at fast from 21.00 h on the day before. To avoid, during the intervention phase, the consumption of green tea and the dietary supplements known to affect glucose and lipid metabolism.	No significant change in total estimated energy.	not specified	Macronutrient composition not specified.
Hill, 2007	Intervention trial.	TEAVIGO.	2 capsules/day containing 150 mg of EGCG (total EGCG intake 300 mg/day)	Placebo: lactose	38 overweight or obese postmenopausal women.	12 weeks.	To maintain the normal diet and physical activity patterns (in addition to completing the required exercise sessions) during the study.	Energy intake and background energy expenditure remained constant throughout the intervention for both treatment groups.	Not specified.	Usual diet. Macronutrient composition not specified.
Chantre, 2002	Open study.	EXOLISE®.	2 times/day (i.e., 2 capsules in morning and 2 capsules at midday) a green tea extract AR25®; ingestion of 4 capsules containing AR25 provided a daily total of 375 mg of catechins, of which 270 mg were epigallocatechin gallate.		70 overweight and obese subjects (7 males and 63 females).	12 weeks.	Not specified.	Administration of green tea extract stimulated thermogenesis and fat oxidation and this extract has the potential to influence body weight and body composition via changes in both energy expenditure and substrate utilization.	Not specified.	Not specified.
Acute Intake
Thielecke, 2010	Randomized, placebo controlled, and double-blind crossover trial.	TEAVIGO, a highly purified extract from green tea leaves (Camilla sinensis) containing minimum 94% EGCG and maximum 0.1% caffeine.	- Low EGCG (300 mg). - High EGCG (600 mg).	Placebo: lactose.	10 overweight or obese men.	3 days.	During the study, no caffeine and catechin-containing drinks and food were allowed.	In all the four groups, EE did not change significantly over the following 240 min before the intake of the test meal and showed an almost identical postprandial time course vs placebo.	Calorimetry, oxygen consumption (VO2, mL/min). and carbon dioxide production (VCO2, mL/min) were measured by a ventilated hood system (Deltatrac II, GE Healthcare, Freiburg, Germany). Fasting and postprandial EE.	The meal provided 5 kcal/kg body weight with 50, 35 and 15% of energy from carbohydrates, lipids and proteins, respectively.
Gregersen, 2009	Cross-over, double-blinded, and placebo-controlled design.	Unilever Colworth.	Group 1: caffeine plus a catechin mixture (600 mg) enriched in either EGCG, epigallocatechin, or a mix of catechins.	Group 2: placebo. Group 3: caffeine alone (150 mg).	15 healthy men.	1 day.	To refrain from exercise and eliminate consumption of foods or beverages containing caffeine (coffee, tea, cola, etc.) and catechins (chocolate, red wine, apples and pears) for 24 h before each chamber stay.	The multivariate ANOVA showed no significant overall treatment effect on EE.	Ventilated hood system.	Standardized meals. Macronutrient composition not specified.
Boschmann, 2007	Randomized double blind, placebo-controlled, and cross-over pilot study.	TEAVIGO™ containing at a minimum 94% EGCG and at a maximum 0.1% caffeine.	Two capsules of 150 mg of EGCG daily for 2 days prior to testing.	Not specified.	6 overweight men.	2 days.	Not specified.	After intake of the meal, EE changed in the same way with both treatments, i.e., a strong initial increase followed by a slow decrease towards the end of the measurement.	Indirect calorimetry with a canopy device.	Test meal containing 5 kcal/kg body weight with 50%, 35%, and 15% energy from carbohydrates, lipids, and proteins, respectively.
Dullo, 1999	Randomized controlled trial.	Capsules containing the green tea extract AR25 provided daily a total of 150 mg of caffeine and 375 mg of catechins, of which 270 mg were epigallocatechin gallate.	1) A green tea extract containing 50 mg of caffeine and 90 mg of epigallocatechin gallate, 2 capsules 3 times/day.	2) 50 mg of caffeine. 3) A placebo that consisted of cellulose as inert filler.	10 healthy men.	3 separate occasions.	Not specified.	Relative to placebo, treatment with the green tea extract resulted 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).	Indirect calorimetry during the stay in the respiratory chamber.	13% of energy as protein, <40% as fat, and <47% as carbohydrates.

Abbreviations: EGCG, epigallocatechin gallate; VO2, oxygen consumption; VCO2, carbon dioxide production; ANOVA, analysis of variance; EE, energy expenditure; RQ, respiratory quotient.