Does green tea make you lose weight?

Very little, and it is disputed. One meta-analysis finds 1.31 kg of difference versus control, while the Cochrane review, with stricter criteria, finds 0.04 kg outside Japan, not statistically significant and not clinically important. What moves weight is the calorie deficit.

How much green tea extract is safe?

EFSA concludes that from 800 mg of EGCG a day taken as a food supplement there is clinical trial evidence of a significant rise in transaminases. Supplements on the market reach that figure, so it is worth reading the EGCG on the label and not just the milligrams of extract.

Is drinking green tea the same as taking capsules?

No. EFSA considers catechins from a traditionally prepared infusion generally safe at European intake levels, and directs the liver toxicity warning at concentrated extract in supplements. Concentrating changes the product.

Is the effect from the catechins or the caffeine?

It is not settled, but the meta-analysis saw that in people already taking more than 300 mg of caffeine a day the effect almost disappears, which suggests caffeine does much of the work. Caffeine has its own, much better evidence, and it is cheaper on its own.

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Green tea · Weak evidence

What green tea is for and what it does

The short answer. Green tea as an infusion is a drink. The extract in capsules is something else: it concentrates the catechins, mainly EGCG, and is sold for fat loss. There the evidence is weak and contradictory. One meta-analysis finds a little over a kilo of difference versus control; the Cochrane review, with stricter criteria, finds a loss so small it is neither significant nor clinically important. And there is a safety fact almost nobody mentions: above 800 mg of EGCG a day from supplements, rises in liver transaminases have been seen.

Reviews find no consistent effect. It is listed because it sells, not because it works. No figure on this page is attributed to a specific product: the effect belongs to the ingredient and every number carries its source next to it.

01 What it does and how much

Each row is a measured effect, with the figure the study gives and the source number. Where the evidence gives no figure, the column says so instead of making up a percentage.

Effects of green tea with their source
Effect	How much	Detail
Body weight (meta-analysis)	-1.31 kg	Eleven studies. The figure is the mean difference versus control, counting both weight loss and maintenance of lost weight. The meta-analysis itself describes it as a small effect. [1]
Body weight (Cochrane review)	-0.04 kg	In the six studies conducted outside Japan, practically zero and not significant. The review concludes the loss is small, not significant and unlikely to be clinically important. [2]
Maintenance of lost weight	no significant effect	This is where it is most often sold as useful, after a diet, and it is where the Cochrane review finds no effect. [2]
Effect of habitual caffeine intake	-0.27 vs -1.60 kg	In people consuming more than 300 mg of caffeine a day the effect almost disappears compared with low consumers, although the difference did not reach significance. It fits the suspicion that much of the effect comes from caffeine, not catechins. [1]
Liver damage threshold	800 mg EGCG/day	EFSA concludes there is evidence from clinical trials that doses of 800 mg of EGCG a day or more taken as a food supplement raise transaminases in a statistically significant way. Supplements on the market reach 1000 mg of EGCG a day. [3]

02 How to take it

Dose. Supplements on the market provide between 5 and 1000 mg of EGCG a day. The relevant safety limit is staying below 800 mg.
When. No time of day is backed for the weight effect. It is tolerated worse on an empty stomach.
How long before you notice it. The trials in the Cochrane review last 12 to 13 weeks.

Details that change the result

EFSA considers traditionally prepared infusions generally safe at the consumption levels usual in Europe. The warning is for concentrated extract in capsules.
Check the EGCG on the label, not the milligrams of extract: they are different figures and the one that matters for safety is EGCG.
Many green tea products have added caffeine. Then what you feel is the caffeine, which does have its own evidence.
Rare cases of liver damage have been described even with infusions, described as an idiosyncratic reaction. Rare, but real.

03 When it makes sense and when it does not

Worth it if

As an infusion, the format with the best safety profile and the one EFSA considers generally safe at usual intakes.
If you want to try the extract, making sure daily EGCG stays clearly below 800 mg.

Not worth it if

Expecting it to solve fat loss: the Cochrane review puts it at a figure with no clinical importance.
With any liver problem, or combining several products containing green tea extract without adding up total EGCG.
As a substitute for a calorie deficit, which is what actually moves weight.

04 Sources

Every figure above comes from here. They are position stands from scientific societies, meta-analyses and peer-reviewed reviews: if a claim cannot hang from one of these lines, it is not on the page. References are cited in their original form.

Hursel R, Viechtbauer W, Westerterp-Plantenga MS. The effects of green tea on weight loss and weight maintenance: a meta-analysis. Int J Obes. 2009;33(9):956-961. Once estudios: las catequinas redujeron el peso en 1,31 kg frente a control; el efecto fue de -0,27 kg con consumo habitual alto de cafeina y de -1,60 kg con consumo bajo. doi:10.1038/ijo.2009.135
Jurgens TM et al. Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database Syst Rev. 2012;12:CD008650. Seis estudios fuera de Japon: diferencia media de -0,04 kg (IC 95 % -0,5 a 0,4); la perdida es pequena, no significativa y poco probable que sea clinicamente importante, y no hubo efecto sobre el mantenimiento del peso. doi:10.1002/14651858.CD008650.pub2
EFSA ANS Panel. Scientific opinion on the safety of green tea catechins. EFSA Journal. 2018;16(4):5239. Hay evidencia de ensayos clinicos de que dosis iguales o superiores a 800 mg de EGCG al dia tomadas como complemento alimenticio inducen un aumento estadisticamente significativo de las transaminasas sericas; los complementos del mercado aportan entre 5 y 1000 mg de EGCG al dia. doi:10.2903/j.efsa.2018.5239

This is not medical advice. It is what some studies say about an ingredient, not a protocol for you. With an illness, medication or pregnancy involved, the decision belongs to a healthcare professional who knows you.

Questions about green tea

Answered with the data on this page

Does green tea make you lose weight?: Very little, and it is disputed. One meta-analysis finds 1.31 kg of difference versus control, while the Cochrane review, with stricter criteria, finds 0.04 kg outside Japan, not statistically significant and not clinically important. What moves weight is the calorie deficit.
How much green tea extract is safe?: EFSA concludes that from 800 mg of EGCG a day taken as a food supplement there is clinical trial evidence of a significant rise in transaminases. Supplements on the market reach that figure, so it is worth reading the EGCG on the label and not just the milligrams of extract.
Is drinking green tea the same as taking capsules?: No. EFSA considers catechins from a traditionally prepared infusion generally safe at European intake levels, and directs the liver toxicity warning at concentrated extract in supplements. Concentrating changes the product.
Is the effect from the catechins or the caffeine?: It is not settled, but the meta-analysis saw that in people already taking more than 300 mg of caffeine a day the effect almost disappears, which suggests caffeine does much of the work. Caffeine has its own, much better evidence, and it is cheaper on its own.

And now, which to buy

Prices, kept apart from the evidence

This page explains what green tea does and deliberately names no brand. The comparison is the other half: 19 products from 2 stores from €0.034 per capsule, sorted by price and by how verifiable their certification is.

See the green tea comparison

Other guides

What each supplement does, with its sources