Green Tea Extract for Weight Loss: Almost No Effect Outside Japan, and High Doses Can Raise Liver Enzymes
Green tea extract (EGCG) is a staple of fat-burner products. A Cochrane review found trials outside Japan produced no meaningful weight loss, and a year-long trial found high-dose capsules raised liver enzymes in some women. Here is what the trials found, who paid for them, and who should be careful.
By Kymata Health Editorial Published Last checked
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What this article covers
1 evidence profileKey takeaways
From 5 sources- In a Cochrane review, 6 trials run outside Japan (532 overweight or obese adults, 12 to 13 weeks) found an average weight difference of just −0.04 kg versus control1.
- Trials in Japan reported −0.2 to −3.5 kg, but they were too different to pool, and the reviewers judged the overall effect too small to be clinically important1.
- In a 12-month trial of 1,021 postmenopausal women, high-dose extract (about 843 mg EGCG a day) raised the liver enzyme ALT by 5.4 U/L more than placebo, and 5.1% developed moderate or worse liver-test abnormalities2.
- Pooled trials of green tea drinks or extracts found small falls in total cholesterol (7.2 mg/dL) and LDL cholesterol (2.2 mg/dL)3.
- Green tea can lower blood levels of nadolol, atorvastatin and raloxifene, and USP-standard labels say not to take the extract on an empty stomach or with a liver problem45.
The evidence, graded
Pulled from the trial tables in our evidence profiles. Grades follow our evidence-grading policy.
Graded findings
3 rows- ∅No effectBody weight in overweight or obese adultsNo effect Weight change versus control was −0.04 kg (95% CI −0.5 to 0.4); Japanese trials (1,030 adults) showed −0.2 to −3.5 kg but could not be pooled.Green tea extract (EGCG) · Systematic review · n=532 · 2012 · PMID 23235664
- BGrade BLiver enzyme elevation (harm)Worsened ALT rose 5.4 U/L on extract versus a 0.5 U/L fall on placebo; 5.1% of women on extract developed moderate or worse liver-test abnormalities (odds ratio 7.0), which resolved on stopping and recurred on rechallenge.Green tea extract (EGCG) · RCT · n=1,021 · 2017 · PMID 28765194
- BGrade BTotal and LDL cholesterolImproved Total cholesterol fell 7.2 mg/dL and LDL 2.2 mg/dL versus control; HDL did not change.Green tea extract (EGCG) · Meta-analysis · n=1,136 · 2011 · PMID 21715508
Why green tea extract is sold for weight loss
Green tea contains catechins, mainly EGCG, plus caffeine, and both are thought to raise energy use a little, which is the basis of weight-loss claims1. Extracts concentrate the catechins into capsules, and some weight-loss products mix green tea with other ingredients5.
NCCIH, part of the US National Institutes of Health, reports no safety concerns for green tea drunk as a beverage by adults; the liver questions below are about concentrated extracts5.
What the weight-loss trials found
The 2012 Cochrane review included randomised trials lasting at least 12 weeks in overweight or obese adults1. Because results differed so much, the reviewers split them by country1.
Six trials outside Japan (532 people) found a mean weight difference of −0.04 kg (95% CI −0.5 to 0.4), a body-mass-index difference of −0.2, and a waist difference of −0.2 cm, none of them significant1. Eight trials in Japan (1,030 people) reported weight losses of 0.2 to 3.5 kg in favour of green tea, but could not be pooled1. Two trials of keeping weight off after a diet found no significant effect1.
The reviewers concluded that green tea preparations produce a small, non-significant weight loss that is unlikely to be clinically important; they declared no known conflicts of interest1.
For other supplements sold for weight loss, see our explainers on yerba mate and L-carnitine, and for caffeine limits, how much caffeine is too much.
The liver question
The best test of liver safety comes from the Minnesota Green Tea Trial, which gave 1,075 postmenopausal women decaffeinated green tea extract capsules or placebo for 12 months to study breast cancer risk markers2. The extract supplied about 1,315 mg of catechins a day, including 843 mg of EGCG, roughly the EGCG in five cups of brewed green tea2.
Among 1,021 women with normal liver tests at the start, ALT rose by 5.4 U/L and AST by 3.8 U/L more on extract than placebo2. 26 women on extract (5.1%) developed moderate or worse liver-test abnormalities, an odds ratio of 7.0 (95% CI 2.4 to 20.3)2. ALT returned to normal when the extract was stopped and rose again when it was restarted, which strongly implicates the extract2.
The trial was funded by the US National Cancer Institute, and the capsules were made and provided by Corban Laboratories/Eniva Nutraceutics2.
A 2020 United States Pharmacopeia (USP) review found published case reports of liver injury at EGCG intakes from 140 mg to about 1,000 mg a day, with large differences between people4. It also found that taking concentrated doses while fasting raises EGCG levels in the blood, and USP now requires labels to say: take with food, do not use with a liver problem, and stop if signs such as dark urine, abdominal pain or yellow skin appear4. Some review panel members disclosed employment with supplement or ingredient makers, including green tea extract suppliers4.
A small effect on cholesterol
A 2011 meta-analysis of 14 randomised trials (1,136 adults) of green tea drinks or extracts found total cholesterol fell by 7.2 mg/dL and LDL by 2.2 mg/dL, with no change in HDL3. These are small changes, and its PubMed record lists no funder3. The green tea extract page grades each finding.
Who should be careful
Check with a doctor or pharmacist before taking green tea extract if any of these apply:
- Liver disease: USP-standard labels say not to use green tea extract with a liver problem4, and in the year-long trial 5.1% of healthy women developed liver-test abnormalities2.
- Taking nadolol (a beta-blocker): high intake of green tea lowered blood levels of this drug, which can reduce its effect5.
- Taking atorvastatin: green tea extract can reduce blood levels of this cholesterol drug5.
- Taking raloxifene for bone health: an NCCIH-funded study found green tea lowered raloxifene exposure5. Green tea may interact with other medicines too, so tell your pharmacist5.
- Taking the extract on an empty stomach: fasting doses raise EGCG levels, which is why USP labels say to take it with food4.
- Pregnancy, breastfeeding or caffeine sensitivity: green tea is a source of caffeine, and NCCIH lists raised blood pressure, nausea and stomach upset among extract side effects5.
Quick answers
Common questions
4 answersHow much EGCG is in green tea extract?
Is drinking green tea the same as taking the extract?
No. NCCIH reports no safety concerns for green tea as a drink for adults, while liver injury has been reported mainly with extract tablets or capsules5.
Does green tea extract burn belly fat?
Trials outside Japan found no significant change in waist size (−0.2 cm)1.
What are the signs of liver trouble from green tea extract?
USP labels list abdominal pain, dark urine and yellowing of the skin or eyes, and say to stop and see a health care practitioner if they appear4.
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Where to buy Green tea extract (EGCG)
Products from brands we partner with that contain Green tea extract (EGCG). Check the amount per serving against the doses studied, and the label for other ingredients.
Green tea extract (EGCG) products from partner brands
3 products Paid links · we earn a commission- HerbsProNOW Foods EGCg Green Tea Extract, 400 mg, 180 Vcaps
1 veg capsule: 400 mg green tea leaf extract (min. 80% catechins, 50% EGCg = 200 mg; up to 4 mg naturally occurring caffeine)
$18.97one-timeChecked Oct 14, 2026 - SupersmartEGCG5% off with the Supersmart newsletterGet 5% off with the newsletter (paid link, opens in new tab)
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- Offer terms from Supersmart’s site, checked Oct 16, 2026. Offers can change; the brand's checkout is final.
2 capsules: 455 mg EGCG (green tea extract standardized to 70% EGCG); 30 servings. This is about half the 843 mg/day that raised liver enzymes in a year-long trial but inside the 140–1,000 mg/day range seen in liver case reports; take with food and not with a liver condition.
$39.00one-time$33.15subscribeChecked Oct 11, 2026 - Renue by ScienceRenue by Science LIPO EGCG Green Tea, liposomal capsules (90)Subscribe & Save 10%
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- 10% off subscription orders on the products we list (prices on each card).
- Offer terms from Renue by Science’s site, checked Oct 15, 2026. Offers can change; the brand's checkout is final.
1 capsule: 150 mg green tea extract (Camellia sinensis), standardized to 90% total catechins and 70% EGCG; 90 servings
$44.95one-time$40.46subscribeChecked Oct 15, 2026
References
5 sources. Numbers in the text link here.
Sources cited in this article
5 sources- 1Green tea for weight loss and weight maintenance in overweight or obese adultsCochrane Database Syst Rev, 2012 · PMID 23235664
- 2Effect of Green Tea Supplements on Liver Enzyme Elevation: Results from a Randomized Intervention Study in the United StatesCancer Prev Res (Phila), 2017 · PMID 28765194
- 3Green tea intake lowers fasting serum total and LDL cholesterol in adults: a meta-analysis of 14 randomized controlled trialsAm J Clin Nutr, 2011 · PMID 21715508
- 4United States Pharmacopeia (USP) comprehensive review of the hepatotoxicity of green tea extractsToxicol Rep, 2020 · PMID 32140423
- 5Green Tea: Usefulness and SafetyNational Center for Complementary and Integrative Health (NIH), 2025
Green tea extract (EGCG) and other dietary supplements are not intended to diagnose, treat, cure or prevent any disease, and these statements have not been evaluated by the FDA. Talk to your clinician or pharmacist before starting a supplement, especially if you take prescription medicines. Product links on this page are paid partner links.