Green tea, derived from the Camellia sinensis plant, has been a staple in traditional Chinese medicine for centuries. While gaining popularity in the West, it's touted for numerous health benefits, including weight loss. This article explores the evidence surrounding green tea tablets and their effectiveness in promoting weight loss, considering various research findings and expert opinions.
What is Green Tea and Green Tea Extract?
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.
Green tea extract is a concentrated form of the beneficial compounds found in green tea leaves. These compounds include caffeine and polyphenols, particularly catechins, with epigallocatechin-3-gallate (EGCG) being the most prominent. These antioxidants are believed to be responsible for many of green tea's purported health benefits. Green tea supplements are concentrated with high amounts of antioxidants that would be nearly impossible to reach by drinking normal amounts of tea, says Naumovski. Some product labels list the EGCG amount per capsule, others list total polyphenols-EGCG and its catechin cousins, and some also list L-theanine, a green tea amino acid linked to brain benefits.
How Green Tea May Affect Weight Loss
The potential weight loss benefits of green tea are attributed to its composition, primarily caffeine and catechins.
Caffeine: Caffeine stimulates thermogenesis, helping your body burn more calories throughout the day. It also boosts alertness and enhances energy production. Research suggests that caffeine in green tea may benefit weight loss when people consume more than 300 mg daily.
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Catechins (EGCG): 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 and body mass index (BMI). These compounds might help reduce absorption of fats and protein in your gastrointestinal tract. Green tea catechins may affect weight markers by reducing total blood cholesterol, low-density lipoprotein and triglycerides. 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.
Metabolism Boost: Green tea contains bioactive substances that may help boost your metabolism and break down fat cells. 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.
Scientific Evidence: Studies and Meta-Analyses
The scientific community presents mixed results regarding green tea's effectiveness for weight loss.
Positive Findings: A randomized, double-blind trial registered under ClinicalTrials.gov Identifier no. NCT02147041, observed significant weight loss, as well as decreases in BMI and waist circumference in the treatment group after 12 weeks of high-dose EGCG treatment. This study also demonstrated a consistent trend of decreased total cholesterol, reaching 5.33%, and decreased LDL plasma levels. A 2023 meta-analysis suggests that green tea supplementation significantly reduced weight, BMI, and waist circumference in women with overweight or obesity. A 2020 review found similar results but suggested that reductions in body weight were more significant at a dosage of less than 500 mg daily for 12 weeks.
Inconsistent Results: A 2022 review suggests that green tea may be effective at reducing total cholesterol, low-density lipoprotein, and triglycerides in animals on an obesity-inducing diet. However, the researchers did not find the same effects in human studies. A 2023 review concluded that green tea extract supplementation had no significant effects on the two appetite-regulating hormones, leptin and ghrelin.
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Modest Impact: Green tea extract supplements were linked with an average weight loss of 1.4 pounds in a study review published in the British Journal of Nutrition.
Dosage and Forms of Green Tea
The dose of green tea supplementation researchers use for weight loss varies across studies.
Dosage Recommendations: 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. A 2020 review found that consuming at least 500 milligrams (mg) of green tea extract daily for 12 weeks helped reduce body weight and BMI.
Forms 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.
Safety and Potential Side Effects
While green tea is generally considered safe, it's essential to be aware of potential side effects and interactions.
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General Safety: 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.
Potential Side Effects: 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). Excess caffeine can cause anxiety, tremors, irritability, headache, and sleeping problems. Herbal or dietary supplements are not regulated like medications. Rigid quality control standards are not required for dietary supplements. The purity and strength of these products can vary.
Interactions with Medications: Green Tea may interact with Aspirin and aspirin-like medications, Clozapine, Dipyridamole, Dyphylline, Furazolidone, Guarana, Iron, Isoniazid, Linezolid, Lithium, MAOIs like Carbex, Eldepryl, Marplan, Nardil, and Parnate, Medications for congestion, colds, Medications for weight loss, Medications that treat or prevent blood clots like cilostazol, clopidogrel, enoxaparin, ticlopidine, warfarin, Other herbal or dietary supplements like ephedra, garlic, ginkgo, Procarbazine, Stimulants like amphetamine, dextroamphetamine, methylphenidate, Theophylline, Yohimbine.
Lifestyle Integration for Optimal Results
Green tea's effects may be lower than those of other weight loss methods, such as exercise and portion management. Effective weight management often requires a multi-faceted approach.
Balanced Diet: Eating a balanced diet with all the necessary nutrients. Optimizing your diet also helps your heart. Adding in more soluble and insoluble fiber and addressing gut health can help with reducing cholesterol in the gut, which will help lower our LDL values a lot more than a than a green tea extract, or really, any supplement for that matter.
Regular Exercise: A 2024 review also found that taking green tea supplements and engaging in regular exercise may help with weight management.
Other Healthy Habits: Making a specific plan with realistic goals, getting plenty of sleep, managing stress, aiming for slow, steady weight loss, keeping a food diary, seeking support from friends, family, or support groups.
Expert Recommendations
Routhenstein recommends skipping green tea extract. Drink up to four cups of green tea per day instead. She likes Sencha by Rishi Tea and Botanicals. If you really want your tea in supplement form, talk to your doctor first, especially if you have diabetes, heart-health issues, or are overweight or over age 50, says Naumovski. Review your health history and medications. Green tea extract can make some drugs less effective.