Green tea extract
Green tea extract is a concentrated supplement made from Camellia sinensis leaves and standardized to varying amounts of catechins, often epigallocatechin gallate (EGCG). It may also contain caffeine. An extract is not equivalent to drinking brewed green tea because concentration, composition, and exposure can differ substantially.
The product is often sold as a fat burner. Catechins with caffeine can modestly affect energy expenditure and fat oxidation, but those short-term mechanisms do not guarantee meaningful fat loss. The NIH Office of Dietary Supplements evidence review concludes that any effect on body weight is small and unlikely to be clinically important; trials of catechins without caffeine have often found no effect. A calorie deficit and a diet that can be maintained remain the central drivers of fat loss.
Green tea extract is also marketed for antioxidant support, reduced inflammation, less muscle soreness, and faster recovery. Changes in an oxidative-stress marker do not establish that a person regains strength sooner or adapts better to training. The human evidence is too sparse and inconsistent to regard the extract as an established treatment for delayed-onset muscle soreness or as a reliable recovery supplement.
Concentrated extracts have a different safety profile from ordinary tea. They can cause nausea, abdominal discomfort, or constipation; when caffeine is present, stimulant effects including a temporary increase in blood pressure are also possible. More importantly, green tea extracts have been linked to uncommon but potentially serious liver injury; concern appears greater with concentrated products taken under fasting conditions. The European Food Safety Authority safety assessment found evidence of liver-enzyme increases at high supplemental EGCG exposure but could not define a generally safe supplemental amount.
People with liver disease or regular medication use, and those who are pregnant, should obtain professional advice before using an extract. A label should state catechin or EGCG content and caffeine rather than merely "green tea," and independent quality testing can help with identity and contamination. It cannot convert a small, uncertain fat-loss or recovery effect into a dependable one.