Green tea, derived from the Camellia sinensis plant, has long been esteemed in traditional Chinese medicine and is gaining recognition in the West for its potential health benefits. Manufacturers make green tea by steaming the leaves of the Camellia sinensis plant. It does not undergo the same fermentation process as other types of tea, such as oolong or black tea, so it retains more antioxidants and nutrients from the plant leaves. Among these potential benefits is its purported ability to aid in weight loss. This article delves into the evidence surrounding green tea and weight loss, exploring its mechanisms, optimal consumption methods, and overall impact.
What is Green Tea?
While it has recently gained popularity in the West, green tea has long been part of traditional Chinese medicine to help with numerous conditions, from headaches to healing wounds. Green tea is a beverage celebrated for its anti-inflammatory, antioxidative, and anticancer effects. Green tea is a popular beverage loaded with antioxidants and various plant compounds.
Unlike oolong or black tea, green tea leaves are steamed, preventing fermentation and preserving their antioxidant and nutrient content. Green tea has been used for thousands of years for its possible medicinal benefits, such as boosting digestion and alertness.
The Science Behind Green Tea and Weight Loss
Green tea contains bioactive substances that may help boost your metabolism and break down fat cells. Green tea is rich in nutrients and antioxidants that may offer some health benefits. However, weight loss research has focused on green tea extracts or supplements, not the beverage. Some people even claim that green tea may help promote weight loss and fat burning.
Tea leaves contain beneficial plant compounds that could help prevent chronic conditions like diabetes and obesity by fighting inflammation and oxidative stress and lowering cholesterol and insulin levels. In particular, green tea contains catechins and caffeine. These may help promote weight loss by increasing the number of calories you burn daily (energy expenditure) and boosting fat oxidation, metabolism, and thermogenesis.
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- Catechins: These are a type of flavonoid, which is a type of plant compound called polyphenols. Tea is especially rich in four catechins: epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), and epigallocatechin gallate (EGCG). Of these four, EGCG is the most abundant, and it is thought to contribute most to the many health benefits of tea, according to a review.
- Caffeine: Green tea’s properties, including caffeine and various polyphenols, may offer beneficial effects on weight, waist circumference, and body mass index (BMI) in some people.
Some research suggests that EGCG may help reduce markers associated with obesity, such as:
- total body weight
- body fat percentage
- waist-to-hip ratio
- waist circumference
- body mass index (BMI)
However, it’s important to note that not all studies support the weight loss effects of EGCG, caffeine, and green tea.
Fat is stored in cells as triglycerides. Ultimately, green tea may help your fat cells break down more fat, which is released into your bloodstream for use as energy by cells like muscle cells. To burn body fat, your body must first break these down into fatty acids and glycerol to move it into your bloodstream. This process is known as fat lipolysis. When you exercise, hormones like epinephrine and glucagon are secreted to help facilitate fat oxidation and the release of fatty acids. These fats are then used as energy and, effectively, burned. This is known as fat oxidation.
Some research suggests that catechins in green tea, especially EGCG, could aid fat oxidation and lipolysis by boosting the effects of some fat-burning hormones like catecholamine.
EGCG may also help inhibit an enzyme that breaks down the hormone norepinephrine. When this enzyme is inhibited, the amount of norepinephrine increases, promoting fat breakdown.
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Caffeine may also help boost fat metabolism, especially when consumed at rest instead of during exercise.
Mixed Research Findings
However, research on the effects of green tea on weight loss is mixed. A 2023 meta-analysis highlights mixed results on the tea’s effectiveness for weight loss. However, the researchers concluded that green tea supplementation had no impact on lipid markers like cholesterol and triglyceride levels.
For instance, a 2023 review concluded that green tea extract supplementation had no significant effects on the two appetite-regulating hormones, leptin and ghrelin. However, the authors did find that green tea extract helped reduce body fat percentage, BMI, and malondialdehyde, a marker of oxidative stress.
When it comes to actual pounds lost, the effects of green tea are relatively modest. However, some human and animal studies have found that green tea extracts and catechins may contribute to losing visceral fat, which surrounds your organs. High amounts of visceral fat are associated with chronic conditions like obesity, type 2 diabetes, and heart disease.
It is important to note that any benefits of green tea for weight loss are likely to be very small. This tea’s effects may be lower than those of other weight loss methods, such as exercise and portion management.
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How Green Tea Affects Weight Loss
A 2023 review suggests that the polyphenols in tea may contribute to its benefits for weight loss. The review also highlights research suggesting that caffeine in green tea may benefit weight loss when people consume more than 300 mg daily.
Research in animals and test tubes also suggests that green tea catechins may affect weight markers by reducing:
- total blood cholesterol
- low-density lipoprotein
- triglycerides
However, the review authors highlight that green tea’s beneficial components may only be effective when a person consumes large amounts over a consistent period.
Impact on Metabolism and Fat Burning
Your body is constantly burning calories and using energy, even when you’re sleeping or sitting down. According to a 2021 review, some studies found that green tea extract may help boost resting metabolic rate (RMR), which could help you burn more calories at rest by increasing your total energy expenditure.
That said, the authors note that not all studies found positive results. More research is needed to understand how green tea may affect RMR.
Many commercial weight loss and fat-burning supplements have green tea listed as an ingredient. However, it’s important to note that the research on green tea’s fat-burning effects during exercise is mixed. For instance, a small 2018 study found that drinking Matcha green tea before exercise helped boost exercise-induced fatty oxidation. A 2024 review also found that taking green tea supplements and engaging in regular exercise may help with weight management.
Lastly, a 2017 review found that some studies reported benefits from ECGC on energy expenditure and fat oxidation when paired with an exercise regimen. However, the authors also found that some other studies reported no significant effects from ECGC when paired with exercise.
More research is needed to fully understand the fat-burning effects of green tea when paired with exercise or at rest.
Appetite Regulation and Calorie Intake
Some people suggest that drinking green tea may help you consume fewer calories, which may contribute to maintaining a calorie deficit and, therefore, losing weight. However, studies show conflicting results on the effects of green tea on appetite.
A 2022 study of 21 people also found that drinking green tea before breakfast helped increase energy expenditure.
However, participants who drank green tea reported increased feelings of hunger. This suggests green tea’s effects on energy expenditure may not be related to increasing feelings of fullness or reducing your caloric intake.
Dosage and Consumption Methods
The dose of green tea supplementation researchers use for weight loss varies across studies.
For example, the 2023 meta-analysis suggests that 1,000 mg or less of green tea daily over 8 weeks or less may offer weight loss benefits.
However, the 2020 review suggests that results were more significant when people consumed less than 500 mg daily for 12 weeks.
Types of Green Tea
Green tea comes in several varieties, but for weight loss, there are unlikely to be significant differences between them. Plain, minimally processed green teas are likely to retain the richest nutritional content.
Integrating Green Tea Into Your Routine
If people want to introduce green tea to their routine, they can speak with a healthcare professional about the most suitable dose.
Safety and Potential Risks
According to the NCCIH, green tea is safe in doses of up to 8 cups daily.
This limit is smaller in people who are pregnant or breastfeeding. The NCCIH recommends consuming no more than 6 cups, or around 300 mg of caffeine, daily.
In rare cases, green tea can cause liver problems, but this may be more likely when consuming green tea extract in pill form. Green tea may also interact with certain medications. For example, the NCCIH states that high doses of this tea can reduce blood levels, which can affect the beta-blocker nadolol (Corgard).
People need to consult a healthcare professional before drinking large amounts of green tea to ensure they are consuming a safe dose. Doctors may advise avoiding green tea if it is likely to interact with any current medications.
Additional Weight Loss Strategies
- making a specific plan with realistic goals
- exercising regularly
- getting plenty of sleep
- managing stress
- aiming for slow, steady weight loss
- eating a balanced diet with all the necessary nutrients
- keeping a food diary
- seeking support from friends, family, or support groups
Tea as a Low-Calorie Alternative
If your beverages are typically high-calorie, swapping in tea may lead to weight loss. For example, trading a sugar-laden mocha for a zero-calorie tea at the coffee shop can easily save you a few hundred calories, notes Sarah Koszyk, RDN, the San Francisco-based author of 365 Snacks for Every Day of the Year.
The Role of Catechins in Weight Loss
Research suggests that tea may also play a direct role in weight loss. “Teas contain catechins, which can increase metabolism by stimulating the body to break fats down more quickly and burn more calories,” Koszyk says.
Limitations in Research
Robust Research on Tea and Weight Loss Is Lacking That said, many studies look at the effects of tea in capsule or tablet form, which may provide study participants with a more concentrated dose of plant compounds like EGCG than a typical bag of tea would. Other studies don’t use humans, and if they do, the population sizes are on the smaller side. These are major limitations, so more large studies in humans using brewed tea are needed before scientists understand and can better determine any potential weight loss benefits for people.
Green Tea and Ginger
Both green tea and ginger have been shown to have health benefits when ingested on their own. Throughout history, green tea has been thought to aid in digestion, regulate body temperature, and control bleeding. Scientific studies support its ability to ease nausea and vomiting linked to pregnancy, surgery, cancer therapy, and motion sickness. Ginger is also proven to lower inflammation and pain. So, it’s not surprising to think that ginger and green tea would have health benefits when had together.
Some studies show that green tea and ginger may help with weight loss. In one study, weight loss capsules containing green tea, ginger, and capsaicin (the spicy component of chili peppers) were much more effective in promoting weight loss than a placebo.
But more research is needed to know how much the capsaicin contributed to those results.
Other Potential Health Benefits of Green Tea
Many health benefit claims have been made about green tea for centuries. Traditionally, in China and India, green tea was a medicine for controlling bleeding, aiding digestion, and regulating body temperature. In modern times, research has been able to show some of its health benefits more solidly than others.
- Heart health: One large study in Japan followed 40,000 adult participants over 11 years and showed that daily consumption of green tea was linked to a low risk of death from cardiovascular diseases. The minimum daily consumption needed to see this benefit was five cups per day.
- Diabetes: Green tea can help regulate your blood sugar levels. It lowers your fasting blood sugar and HbA1c when you have type 2 diabetes.
- Stroke prevention: Another large Japanese study, this one following more than 82,000 participants over 13 years, showed that higher consumption rates of green tea were associated with a reduced risk of stroke.
- Genital wart treatment: The FDA has approved a topical green tea extract treatment to treat breakouts of genital warts.
- Benefits for your skin: Studies show green tea may have anti-inflammatory and anticancer benefits that may help you have healthier skin.
- Cancer prevention: Some studies suggest higher green tea intake can lower the odds of getting breast cancer or having a recurrence.
- Easing painful periods: Green tea with or without ginger is sometimes used to ease painful periods.
- Prostate cancer: Some research points to a lower risk of prostate cancer in men who drink more green tea, but results have been mixed.
- Healthy aging: There’s some evidence that drinking green tea over time may help with healthy aging.
- Cognitive decline: Green tea has also been tied to lower risk of cognitive decline.
Potential Risks and Side Effects
There isn't much evidence that drinking green tea and ginger could be harmful. But too much ginger can cause diarrhea, heartburn, and even an irregular heartbeat. While it would be pretty hard to overdose on ginger by drinking ginger and green tea, it’s much easier to do so by taking diet pills that promote their green tea and ginger content.
Always check with your doctor before taking supplements, and follow dosing instructions carefully. Drinking eight cups per day or less of green tea is considered safe for most adults. But there are risks posed by drinking green tea in high concentrations, especially as an extract.
In rare cases, green tea extract may cause liver problems. While the research is limited, you should avoid green tea extract if you have liver problems.
Stop taking green tea extract and contact your doctor if you have abdominal pain, dark urine, or jaundice.
What Not to Take with Green Tea
Green tea, whether caffeinated or decaf, can reduce iron absorption. So, it’s best to take iron supplements separately. Green tea may interact with some medications, including those used to treat high blood pressure, heart problems, and osteoporosis. Ask your doctor what’s safe.
Incorporating Green Tea into Your Diet
Is it good to drink green tea on an empty stomach? Yes, it’s fine for most people. But there’s no proof you’ll get more health benefits this way. There are plenty of beverages that claim they can help you sip away the pounds, from protein shakes to bone broth to lemon water. But the humble little drink that may be the all-time champion when it comes to weight loss is a cup of green tea.
Here’s a recipe for green tea:
- 3 cups filtered water
- 4 green tea bags
- 1 tablespoon ginger root, peeled and thinly sliced
- 2 tablespoons fresh lemon juice, plus 4 slices for garnish
- 2 tablespoons honey
Then follow these directions:
- Bring water to just below boiling point. Remove from heat.
- Place tea bags in a pitcher, and add ginger slices. Pour hot water over the tea bags. Let them steep for 8-10 minutes. Remove the tea bags. Stir in lemon juice and honey.
- Serve warm or iced.
There’s no evidence that, health-wise, it matters when you drink green tea. That’s a matter of your personal preference.