VoltraDoes green tea help you lose weight? What studies show, caffeine per cup, and green tea pills
Barely. In a Cochrane review of trials lasting 12 to 13 weeks, overweight adults taking green tea preparations outside Japan lost 0.04 kg more than those on a control, a difference the authors judged "not likely to be clinically important" [1].
A cup of plain green tea has about 2 kcal (calculated) and 13 to 29 mg of caffeine, depending on whose figure you use [4][5]: less than a cup of black tea. The risk is in pills: 800 mg or more of EGCG a day from supplements raised liver enzymes in trials [3].
Does green tea help you lose weight?
The best summary is a 2012 Cochrane review of 15 weight-loss trials and 3 weight-maintenance trials, with 1,945 people who finished them, each lasting 12 to 13 weeks [1]:
- Outside Japan, six trials with 532 people: green tea groups lost 0.04 kg more than control groups. The true difference could lie anywhere from 0.5 kg more to 0.4 kg less (95% confidence interval) [1].
- Waist: in five of those trials, 0.2 cm smaller, a difference that wasn't statistically significant [1].
- In Japan, eight trials found 0.2 to 3.5 kg more weight loss with green tea, but they differed too much to be combined [1].
- Keeping weight off after a diet: green tea had no significant effect [1].
The review describes green tea weight-loss preparations as extracts with more catechins and caffeine than tea brewed from a tea bag [1]. The US National Center for Complementary and Integrative Health (NCCIH) says green tea's catechins and caffeine "may have a modest effect on body weight", and that this varies with the product and with how active you are [2].
So over a month, the difference studies can measure is close to nothing: 0.04 kg over about three months. Weight comes off with a calorie deficit; see how many calories you need a day.
Caffeine and calories in a cup
| Drink | Serving | Caffeine | Per 100 ml |
|---|---|---|---|
| Green tea, SFDA [5] | Cup, 250 ml | 13 mg | 5 mg |
| Green tea, USDA [4] | Cup, 245 g | 29 mg | 12 mg (per 100 g) |
| Arabic coffee [5] | Finjan, 50 ml | 27 mg | 53 mg |
| Black tea [5] | Cup, 250 ml | 54 mg | 22 mg |
| Black coffee [5] | Cup, 250 ml | 145 mg | 58 mg |
The Saudi Food and Drug Authority's (SFDA) caffeine guide says its values come from SFDA lab analyses or the makers' own information [5]; rounded. USDA gives 12 mg per 100 g of brewed green tea; the cup is calculated with USDA's 245 g cup [4].
The two figures for green tea differ more than twofold. That's not surprising: the European Food Safety Authority (EFSA) notes that what ends up in a cup of green tea depends on how it's made, from the amount of tea and water to the water's temperature and the brewing time [3]. Either way, a cup of green tea has less caffeine than a cup of black tea, and about as much as a finjan of Arabic coffee or less [4][5]. Our Arabic coffee guide has more on gahwa.
Plain green tea has about 1 kcal per 100 g, so about 2 kcal a cup (calculated) [4]. The calories are in what you add: a teaspoon of sugar (4.2 g) is about 16 kcal and a tablespoon of honey (21 g) about 64 (calculated) [7][8]. For comparison, a 250 ml cup of karak made with evaporated milk and sugar is about 130 kcal (calculated) [6]; see our karak guide.
Green tea pills and extracts
Most of the safety problems are with extract pills. EFSA reviewed green tea catechins in 2018 [3]:
- Drinking green tea gives adults in Europe 90 to 300 mg a day of EGCG, its main catechin, on average; supplements give 5 to 1,000 mg a day [3].
- In trials, 800 mg or more of EGCG a day taken as a supplement raised liver enzymes (transaminases), a sign of liver injury [3].
- EFSA couldn't name a dose of green tea extract it considers safe, and liver injury was reported with one product at 375 mg of EGCG a day [3].
- Green tea made the traditional way is in general considered safe. Rare cases of liver injury after drinking it were most probably individual reactions [3].
NCCIH lists nausea, constipation, stomach discomfort and raised blood pressure as side effects of extract supplements [2]. Liver injury is uncommon and mostly linked to extract tablets or capsules; people with a particular gene variant, carried by 5 to 15% of Americans, appear more susceptible [2]. Some weight-loss products also mix green tea with other ingredients [2], so check the label for the EGCG per day.
Does green tea raise blood pressure?
As a drink, NCCIH says no safety concerns have been reported in adults, though green tea does contain caffeine [2]. Raised blood pressure is listed among the side effects of extract supplements [2].
If you take medicines: green tea in high amounts lowers blood levels of nadolol, a beta-blocker for blood pressure and heart problems, and green tea extract lowers levels of atorvastatin, a cholesterol drug [2]. For people with heart and artery disease, the SFDA's caffeine limit is 200 mg a day [5], about 6 cups of green tea on USDA's figure (calculated), counting caffeine from other drinks too.
How many cups a day, and on an empty stomach?
There's no official cup limit for green tea. Two figures help:
- Liver. EFSA found no sign of raised liver enzymes in people drinking 5 or more cups of green tea a day, though it called the data sparse [3]. It puts typical green tea drinking at 3 to 10 cups a day; cup sizes vary between studies [3].
- Caffeine. The SFDA's limit for healthy adults is 400 mg a day [5], about 13 cups of green tea on USDA's figure (calculated). Coffee, black tea and energy drinks count toward the same total; see our caffeine guide.
On an empty stomach: we found no trial comparing green tea drunk before food with green tea after food for weight. For extract pills there is a difference: EFSA notes that green tea extract taken on an empty stomach, all at once, raises EGCG in the blood significantly more than when it's taken with food or in split doses [3].
How to log it in Voltra
- Plain green tea: about 2 kcal a cup, so there's little to log.
- With sugar, honey or milk: on the Eat tab, tap Describe and type it, for example "green tea, 250 ml, 2 teaspoons sugar". Check the grams, then tap Log.
- Bottled green tea: tap Barcode and scan the bottle. If it isn't in Open Food Facts, use Describe instead.
Frequently asked
Does green tea help you lose weight?
Barely. In a Cochrane review of 12- to 13-week trials, overweight adults taking green tea preparations outside Japan lost 0.04 kg more than those on a control. The authors judged that not likely to be clinically important.
How much weight can green tea take off in a month?
Almost none that trials could measure. Outside Japan, the difference after 12 to 13 weeks was 0.04 kg in total, and 0.2 cm off the waist.
Is green tea a fat-burning drink?
Not in a way the scale shows. Outside Japan, green tea preparations changed weight by 0.04 kg and waist size by 0.2 cm over 12 to 13 weeks, and neither difference was statistically significant.
Does green tea have caffeine, and how much?
Yes. About 29 mg in a 245 g cup on USDA's figure of 12 mg per 100 g (calculated), and 12.67 mg in a 250 ml cup in the Saudi Food and Drug Authority's guide. Either way, less than a 250 ml cup of black tea, which has 54 mg.
How many calories are in green tea?
About 2 kcal in a 245 g cup with nothing added (calculated from USDA). A teaspoon of sugar adds about 16 kcal and a tablespoon of honey about 64.
Does green tea raise blood pressure?
NCCIH reports no safety concerns for green tea as a drink in adults, but it contains caffeine. Raised blood pressure is a listed side effect of green tea extract supplements. In high amounts, green tea lowers blood levels of nadolol, a beta-blocker.
How many cups of green tea a day?
There's no official cup limit. EFSA found no sign of raised liver enzymes at 5 or more cups a day. For caffeine, the SFDA's 400 mg a day for adults is about 13 cups on USDA's figure (calculated), fewer if you also drink coffee or tea.
Is green tea better on an empty stomach?
We found no trial showing that for weight. For extract pills, EFSA notes that taking them on an empty stomach, all at once, raises EGCG in the blood significantly more than taking them with food.
Are green tea pills safe?
Not risk-free. EFSA found that 800 mg or more of EGCG a day from supplements raised liver enzymes in trials, and couldn't name a dose of extract it considers safe. NCCIH lists nausea and raised blood pressure, and rare liver injury, mostly from extract tablets or capsules.
Sources
- Jurgens TM, Whelan AM, Killian L, Doucette S, Kirk S, Foy E (2012). Green tea for weight loss and weight maintenance in overweight or obese adults. Cochrane Database Syst Rev 12:CD008650. Abstract and plain language summary. The authors declared no known conflicts of interest.
- National Center for Complementary and Integrative Health (2025). Green Tea: Usefulness and Safety. Last updated February 2025.
- EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) (2018). Scientific opinion on the safety of green tea catechins. EFSA Journal 16(4):5239. Read in full on PubMed Central (PMC7009618).
- USDA FoodData Central. Beverages, tea, green, brewed, regular (FDC 171917). 1 kcal and 12 mg of caffeine per 100 g. Weight: 1 cup 245 g.
- Saudi Food and Drug Authority, National Nutrition Committee (2021). الدليل الإرشادي لاستهلاك المنتجات المحتوية على الكافيين (guide to consuming products that contain caffeine). In Arabic. Printed p. 8 (limits) and annex 1 on p. 20 (caffeine per drink).
- Ministry of Health, Kingdom of Bahrain (2025). Bahrain Food Composition Tables, 1st edition. Item 2.1, karak tea: 50.5 kcal per 100 g.
- USDA FoodData Central. Sugars, granulated (FDC 169655). Weight: 1 teaspoon 4.2 g.
- USDA FoodData Central. Honey (FDC 169640). Weight: 1 tablespoon 21 g.
Sources checked on 6 October 2026.
Log your food and training with Voltra. Free to download; the yearly plan starts with a 7-day free trial. Works fully in English and Arabic.
