The Truth About Green Tea for Weight Loss: Does It Work?

Green tea is touted as a fat burning supplement. The question is: does it really help with weight loss—or are these claims just some companies' attempts to capitalize on the obesity epidemic plaguing America today? 

As a trainer, your clients expect you to provide an answer to this question based on proven research. We’ll get to that in a minute. But first, let's talk about why green tea is an easy sell. It has to do with its many health benefits.

Health Benefits of Drinking Green Tea

Penn Medicine shares that green tea can help improve heart health (1). It does this by reducing “bad” cholesterol levels and lowering blood pressure. Penn adds that green tea also appears to have a positive impact on several types of cancer. 

Studies have also connected green tea with better blood sugar control (2). This health benefit is provided by lowering fasting blood glucose levels. If these levels get too high, diabetes can develop. 

Green tea can even help boost mental health. According to research, it works by improving mental clarity while also inducing relaxation (3). It also has positive effects on attention and memory.

Part of what makes green tea so powerful from a health standpoint is its catechins. Tea catechins are flavonoids that are potent antioxidants. When talking about green tea catechin specifically, one study found that they make up 80-90% of the flavonoids in this drink (4).

How Does Green Tea Help You Lose Weight?

Another claimed health benefit of green tea is that it promotes weight loss. It is said to work, in part, by the catechins increasing metabolism. This aids in fat loss. Since green tea also has caffeine, another metabolism booster, it may help enhance this effect. Due to this, many label green tea as a fat burner. 

According to an article published in the journal Nutrients, some suggest that green tea catechins increase fat oxidation (5). This is the process whereby fatty acids are broken down. Others contend that green tea helps people lose weight by increasing hormones that tell fat cells to break the fat down. 

What’s the truth? Is green tea a fat burning ingredient or is it all hype? The only way to know is to look at the research. Here’s what it has found.

What Science Says About Green Tea and Weight

A 2017 review looked at the effects of green tea on both body weight and body fat (6). In all, analyzed the results of 15 different studies. Researchers noted that consuming green tea with 100-460 mg of a catechin called epigallocatechin gallato (EGCG) for 12 weeks or more was associated with a greater reduction of body fat and body weight. However, caffeine was also deemed important for these effects, in the amount of 80-300 mg per day.

A 2020 study found similar results (7). This research involved overweight middle-aged men who were split into three groups. One group did endurance training and took a green tea supplement, one group, did training and took a placebo, and the third group took a placebo only (no endurance training. Subjects who took a green tea extract supplement with training had greater improvements in their body weight, body mass index, and body fat percentage than individuals in the other two groups. They also had greater improvements in their visceral fat, which is another word for belly fat.

A 2021 clinical trial combined 146 mg of EGCG with 178 mg of a citrus polyphenol called α-glucosyl hesperidin (8). Researchers noted that this combination prevented weight gain and lowered body mass index better than a placebo. 

Based on studies such as these, it appears that green tea may offer a weight loss benefit. It may even assist with weight maintenance by preventing weight gain. That said, green tea is not suitable for everyone.

Who Should NOT Use Green Tea

A review on the toxicological effects of green tea warns that just because this substance is natural doesn’t mean that it is safe (9). For instance, there is limited research on green tea’s safety during pregnancy and lactation. At least one past study suggests that catechins can reduce the bioavailability of folate. Folate is important for preventing birth defects (10). 

The National Center for Complementary and Integrative Health (NCCIH) adds that, while rare, some people have experienced liver issues after taking green tea products (11). Therefore, individuals with compromised liver function or liver disease should talk with their healthcare provider before consuming this ingredient.

Additionally, consuming high doses of green tea may also reduce the effectiveness of beta-blockers. These medicines are used to treat high blood pressure and heart-related issues. It might even impact the effects of other prescription medications. So, individuals taking any type of prescription drug should also talk with their health provider to determine if green tea is safe to consume.

Green Tea vs. Green Tea Extract

The terms “green tea” and “green tea extract” are often used interchangeably. This is understandable since they both come from the Camellia sinensis plant. (Coincidentally, this is also the plant from which we get black tea, oolong tea, and several others.) Yet, they aren’t the same thing.

Green tea refers to tea that is made using the Camellia sinensis plant’s unoxidized leaves. These leaves are removed from the plant, cooked quickly by either pan frying or steaming them, then dried. This helps preserve the tea while preventing oxidation. 

Green tea extract is a concentrated form of green tea. Oftentimes, it is created using the waste products that are left over after making the tea. Depending on how the green tea extract is manufactured, some of the catechin content may be lost. Some of the tea’s antioxidant properties may have been reduced as well.

Another difference between the two is that only green tea contains caffeine. For people who are sensitive to caffeine, green tea extract may be a better option. If you buy a green tea supplement, it is likely made with an extract. 

If You Use Green Tea for Weight Loss

The NCCIH recommends limiting green tea consumption to no more than 8 cups per day. Remember that regular green tea does contain caffeine. And it may contain more caffeine than is listed on the label. The reason for this is that the product only has to provide the amount of added caffeine, according to the NCCIH, not the caffeine that it contains naturally. So, its caffeine count is likely higher than the label says.

You have a variety of green tea preparations, from which to choose. If you like to brew your own tea, you can purchase green tea leaf and steep it whenever you want a drink. If using a tea leaf seems like too much work, green tea is also available in tea bags. Just place the tea bag in a hot cup of water and you’re ready to go.

For many, this type of tea is an acquired taste, much like matcha. Matcha is actually a green tea, so this makes sense. In this case, green tea supplementation can make it easier to get more of this plant’s healthful nutrients without having to drink green tea. Although, if you do like both flavors, you can also purchase matcha green tea.

Keep in mind that green tea is not a magic weight loss beverage. You can’t just drink it while having a high calorie intake and expect to lose weight. Instead, think of it more as a complement to a healthy diet. 

To learn more about how to create a healthy diet, ISSA offers Nutrition Certification. This course talks about all the nutrients needed for optimal health. It also discusses how to create an eating plan that aids in weight loss. This can be beneficial for yourself, as well as another service you can offer your training clients.

References

1. The Hidden Health Benefits of Tea. Pennmedicine.org. (2022). Retrieved 24 August 2022, from https://www.pennmedicine.org/updates/blogs/health-and-wellness/2019/december/health-benefits-of-tea.

2. Xu, R., Bai, Y., Yang, K. et al. Effects of green tea consumption on glycemic control: a systematic review and meta-analysis of randomized controlled trials. Nutr Metab (Lond) 17, 56 (2020). https://doi.org/10.1186/s12986-020-00469-5

3. Dietz, C., & Dekker, M. (2017). Effect of Green Tea Phytochemicals on Mood and Cognition. Current pharmaceutical design, 23(19), 2876–2905. https://doi.org/10.2174/1381612823666170105151800

4. Reygaert W. C. (2018). Green Tea Catechins: Their Use in Treating and Preventing Infectious Diseases. BioMed research international, 2018, 9105261. https://doi.org/10.1155/2018/9105261

5. Gahreman, D., Wang, R., Boutcher, Y., & Boutcher, S. (2015). Green Tea, Intermittent Sprinting Exercise, and Fat Oxidation. Nutrients, 7(7), 5646–5663. https://doi.org/10.3390/nu7075245

6. Vázquez Cisneros LC, López-Uriarte P, López-Espinoza A, et al. Effects of green tea and its epigallocatechin (EGCG) content on body weight and fat mass in humans: a systematic review Nutricion Hospitalaria. 2017 Jun;34(3):731-737. DOI: 10.20960/nh.753. PMID: 28627214.

7. Bagheri, R., Rashidlamir, A., Ashtary-Larky, D. et al. Effects of green tea extract supplementation and endurance training on irisin, pro-inflammatory cytokines, and adiponectin concentrations in overweight middle-aged men. Eur J Appl Physiol 120, 915–923 (2020). https://doi.org/10.1007/s00421-020-04332-6

8. Yoshitomi, R., Yamamoto, M., Kumazoe, M. et al. The combined effect of green tea and α-glucosyl hesperidin in preventing obesity: a randomized placebo-controlled clinical trial. Sci Rep 11, 19067 (2021). https://doi.org/10.1038/s41598-021-98612-6

9. Bedrood, Z., Rameshrad, M., & Hosseinzadeh, H. (2018). Toxicological effects of Camellia sinensis (green tea): A review. Phytotherapy Research, 32(7), 1163-1180. https://doi.org/10.1002/ptr.6063

10. Yazdy, M. M., Tinker, S. C., Mitchell, A. A., Demmer, L. A., & Werler, M. M. (2012). Maternal tea consumption during early pregnancy and the risk of spina bifida. Birth defects research. Part A, Clinical and molecular teratology, 94(10), 756–761. https://doi.org/10.1002/bdra.23025

11. Green Tea. National Center for Complementary and Integrative Health. (2020). Retrieved 24 August 2022, from https://www.nccih.nih.gov/health/green-tea.