Green tea supplementation can improve obesity indices, with more significant reductions in body weight and waist circumference when dosed at 500 mg/day for 12 weeks.

The effect of green tea supplementation on obesity: A systematic review and dose–response meta‐analysis of randomized controlled trials

Daily intake of green tea catechins may improve working memory in middle-aged and older adults with cognitive decline.

Effect of Daily Intake of Green Tea Catechins on Cognitive Function in Middle-Aged and Older Subjects: A Randomized, Placebo-Controlled Study

Drinking four cups of green tea per day significantly reduced weight and systolic blood pressure in patients with type 2 diabetes.

The effects of green tea consumption on metabolic and anthropometric indices in patients with Type 2 diabetes

Oral green tea extract (GTE) at a dose of 1.0 g/m(2) tid (equivalent to 7 to 8 Japanese cups) can be taken safely for at least 6 months in adult cancer patients with caffeine-related side effects.

Phase I trial of oral green tea extract in adult patients with solid tumors.

Daily consumption of high doses of green tea extract supplements is safe for healthy men, with only a slight reduction in the total:HDL cholesterol ratio.

Daily consumption of an aqueous green tea extract supplement does not impair liver function or alter cardiovascular disease risk biomarkers in healthy men.

Green tea supplementation significantly reduces body weight, BMI, and waist circumference in overweight and obese women, with doses 1000mg/day and duration 8 weeks recommended.

The effect of green tea supplementation on the anthropometric outcomes in overweight and obese women: a time and dose-response meta-analysis of randomized controlled trials.

High-dose green tea extract significantly reduces weight, waist circumference, and cholesterol levels in women with central obesity without side effects or adverse effects.

Therapeutic effect of high-dose green tea extract on weight reduction: A randomized, double-blind, placebo-controlled clinical trial.

Daily supplementation with 379 mg of green tea extract reduces blood pressure, insulin resistance, inflammation, and oxidative stress, and improves lipid profile in obese, hypertensive patients.

Green tea extract reduces blood pressure, inflammatory biomarkers, and oxidative stress and improves parameters associated with insulin resistance in obese, hypertensive patients.

Green tea catechins are generally considered safe, but excessive intake of EGCG in food supplements may cause a significant increase in serum transaminases.

Scientific opinion on the safety of green tea catechins

Green tea consumption in Korea increases daily intake of phenolics, flavonoids, and antioxidants, contributing to overall health benefits.

Estimated daily intake of phenolics and antioxidants from green tea consumption in the Korean diet

Green tea and green tea extract consumption is safe for adults, with hepatotoxicity as the critical effect, and a safe intake level of 338 mg EGCG/day for solid bolus doses and 704 mg EGCG/day for beverage form.

The safety of green tea and green tea extract consumption in adults – Results of a systematic review

Daily supplementary intake of 500 mg green tea polyphenols did not show clear effects on blood glucose level, Hb A1c level, insulin resistance, or inflammation markers.

Randomized controlled trial for an effect of green tea consumption on insulin resistance and inflammation markers.

Green tea catechins may reduce body weight and fat through increased energy expenditure, fat oxidation, and modifications in appetite, with caffeine acting synergistically.

Antiobesity effects of green tea catechins: a mechanistic review.

Green tea supplementation improves total antioxidant capacity and reduces malondialdehyde levels in adults, with dose-dependent effects.

Effect of Green Tea Supplementation on Antioxidant Status in Adults: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Regular green tea supplementation for more than a week before exercise increases antioxidant status and reduces exercise-induced oxidative stress, while acute green tea ingestion does not show significant effects.

Regular, but not acute, green tea supplementation increases total antioxidant status and reduces exercise-induced oxidative stress: a systematic review.

Taking green tea combined with -glucosyl hesperidin prevents weight gain and reduces BMI, with a more pronounced antiobesity effect in people aged  50 years.

The combined effect of green tea and α-glucosyl hesperidin in preventing obesity: a randomized placebo-controlled clinical trial

Drinking three to four cups of tea per day can reduce body weight and alleviate metabolic syndrome, with green tea being more effective than black tea.

Mechanisms of body weight reduction and metabolic syndrome alleviation by tea.

Green tea-based beverages and extracts are considered safe for human consumption, with a tolerable upper intake level of 300mg EGCG/person/day for food supplements.

Safety assessment of green tea based beverages and dried green tea extracts as nutritional supplements.

Green tea catechins may have a protective effect on weight gain in overweight and obese men, but their effect on blood pressure and metabolic function remains unclear.

Health effects of green tea catechins in overweight and obese men: a randomised controlled cross-over trial

Increasing green tea intake (5 cups/day) may have a preventive effect against liver cancer, with a downward trend most obvious when consumption increases up to about 4 cups/day.

Green Tea Consumption and the Risk of Liver Cancer: A Meta-Analysis

These studies suggest that daily green tea intake ranging from 379 mg to 1000 mg of green tea extract or drinking up to 4 cups of green tea can provide health benefits such as weight reduction, improved memory, and better cardiovascular health, but excessive intake may cause liver enzyme elevation.