How Much Green Tea Should You Drink to Lose Weight?

Green tea can aid in weight-loss efforts by reducing appetite and boosting metabolism, according to an article published in the “Journal for Nurse Practitioners" in 2010. Studies have not established an exact daily dose of green tea that will best support weight loss, but you can drink at least 2 to 3 cups a day while staying under the upper limits of recommended caffeine intake. But remember, although green tea can be a helpful aid, the tea alone does not cause weight loss -- only creating a calorie deficit can do that.

Caffeine Intake

The caffeine found in green tea is partly responsible for its weight-loss effects. Caffeine is not without side effects, and too much can cause toxicity. A “Journal for Nurse Practitioners" article warned of the potential for people to abuse supplements that contain caffeine and other stimulants. Green tea contains about 25 milligrams of caffeine per 8 ounces. The upper limit of caffeine intake for healthy adults to avoid harmful effects is 300 to 400 milligrams daily. This limit may be different if you have a health condition, so it's important to speak with your doctor. Pregnant women should have no more than 200 milligrams of caffeine daily.

Avoiding Caffeine Toxicity

To stay within the upper limit of caffeine intake, do not exceed 12 to 16 8-ounce cups of green tea daily. Keep in mind that the strength at which tea is brewed affects its caffeine content. Using one tea bag counts as one cup of tea. If you desire stronger tea, count each tea bag used as an additional cup toward the upper limit.

Sufficient Doses of Polyphenols

The University of Maryland Medical Center recommends drinking 2 to 3 cups of green tea daily to get a sufficient dose of its health-promoting active ingredients. This includes 240 to 320 milligrams of polyphenols. These plant compounds are antioxidants, which means they protect cells from damage. They also may also increase your metabolism. A review and meta-analysis of studies on green tea's effects on weight loss, published in "Nutrición Hospitalaria" in 2014, concluded green tea does reduce fat mass slightly. You can't rely on green tea alone to lose weight, but it can aid in your overall efforts.

Side Effects and Precautions

Side effects of caffeine include increased heart rate, insomnia, nausea and vomiting, frequent urination, tremors, anxiety and depression. Consult with your doctor before drinking green tea if you have a medical condition. If you suffer from heart, kidney or liver problems, high blood pressure, diabetes, anemia, glaucoma, osteoporosis or anxiety, avoid drinking green tea. Green tea also interacts with certain medicines, so talk with your doctor before drinking it if you're taking any medications. Birth control pills, blood thinners and others are known to interact with green tea.