Green Tea Extract (EGCG / Catechins)
A concentrated supplement containing green tea polyphenols, especially EGCG (epigallocatechin gallate). Marketed for weight loss and fat burning. The evidence shows only very modest effects — and high-dose extract supplements carry a rare but serious liver toxicity risk that brewed green tea does not.
Quick read · 3 min
- •Evidence: Weak — limited or inconsistent trial data
- •A Cochrane systematic review found a small, statistically significant weight loss of approximately 0.
- •Brewed green tea is safe for most people.
- •Prescription weight loss drugs produce 7–21% weight loss in trials. Most supplements in this category produce less than 2 kg.
Based on clinical trials · No rankings · Every claim linked to source
Last reviewed: March 2026
How it works
Catechins (especially EGCG) combined with caffeine may modestly increase thermogenesis (calorie burning) and fat oxidation, particularly during exercise. The weight loss effect appears to depend on the presence of caffeine — decaffeinated green tea shows little benefit. The thermogenic effect is mild.
What the evidence shows
A Cochrane systematic review found a small, statistically significant weight loss of approximately 0.95 kg vs. placebo. This is clinically insignificant for most people. The effect appears caffeine-dependent and is not demonstrated with decaffeinated preparations. Most effects are short-term and modest.
Safety
Brewed green tea is safe for most people. However, concentrated green tea extract supplements have been linked to rare but serious liver injury (hepatotoxicity). The FDA has issued a warning about this risk. High-dose concentrated extracts are not equivalent to drinking tea. Caffeine-related side effects apply at higher doses: insomnia, anxiety, and heart palpitations. Not recommended in pregnancy at high doses.
Community insights
These are personal experiences shared in public online communities — not medical advice.
“Brewed green tea is safe and pleasant. The concentrated extract supplements are a different product — the liver toxicity cases are real, even if rare.”
“If you want the thermogenic effect, the combination of caffeine + EGCG from drinking regular green tea is safer than high-dose extracts and roughly as effective.”
Common questions
After reading this page, most people compare this with other supplements, look at prescription options, or check what they can do today without a prescription.