When it comes to weight loss, diet and exercise remain the most effective methods. However, some dietary supplements can also lend a hand. Green tea is one of the safest, best researched, and most effective options.
Both caffeine and catechins (antioxidant polyphenol compounds including epigallocatechin gallate or EGCG) in green tea have thermogenic properties that increase energy (calorie) expenditure and burn fat. Studies suggest green tea can lead to modest weight reduction, making it an effective boost to diet and exercise efforts.
In a small study of healthy men, those taking green tea extract burned 17 percent more fat while cycling compared to those taking a placebo. In this study, green tea also improved insulin levels and insulin sensitivity.
Green tea’s catechins may also impact gut microbes in a way that favors weight loss. The catechins in green tea decrease the fat and protein absorption in the intestines, which reduces the calorie intake from the food you eat, and improves your body’s ability to use fat and protein as fuel. In one study, obese patients who took green tea extract while dieting lost three times more pounds and more significantly reduced their body mass index (BMI) compared to those who just dieted.
Caffeine may not be the most important player, though. While caffeine does help boost exercise performance by about 11 percent, the antioxidants in green tea have other perks. Studies show that EGCG aids weight loss in part by increasing the breakdown of fatty acids associated with obesity. In a study of 40 obese women, those who took a decaffeinated green tea blend after a three-month lifestyle intervention continued to lose weight and decrease fat mass while those who took a placebo gained weight. Also, black tea, which is higher in caffeine but lower in antioxidants, is not as effective as green tea.
To get the best weight-loss results, aim for three to four cups of green tea per day, delivering 600 to 900 milligrams (mg) of catechins. One cup of green tea usually contains 240 to 320 mg catechins and 45 mg of caffeine.
You can reap the most antioxidants from a cup of green tea by purchasing high-quality loose tea, using hotter water, and letting it steep longer (though if you let it steep too long, it gets bitter). I find that green tea gets fishy tasting if stored too long. Green tea should always have a fresh scent, flavor, and color—both dry and brewed. Store green tea in a tightly sealed container in a cool, dark, dry spot or—especially for long-term storage—the fridge.
Several cases of liver toxicity related to green tea weight-loss products have surfaced over the years. The risk appears to be greatest in multi-ingredient weight-loss products and may involve adulteration. When purchasing green tea supplements, opt for high-quality brands and take with food to reduce the risk. Drinking tea is quite safe; it is the second-most popular drink worldwide after water.
“Dietary Supplements for Weight Loss,” National Institutes of Health, https://ods.od.nih.gov
“Effects of Greenselect Phytosome on Weight Maintenance After Weight Loss in Obese Women: A Randomized Placebo-Controlled Study” by L. Gilardini et al., BMC Complement Altern Med, 2016
“Green Tea Extract Ingestion, Fat Oxidation, and Glucose Tolerance in Healthy Humans” by M.C. Venables et al., Am J Clin Nutr, 3/08
“Mechanisms of Body Weight Reduction and Metabolic Syndrome Alleviation by Tea” by C.S. Yang et al., Mol Nutr Food Res, 1/16
“A Minireview of Effects of Green Tea on Energy Expenditure” by D. Turkozu and N.A. Tek, Crit Rev Food Sci Nutr, 1/22/17
“Nutraceuticals for Body-Weight Management: The Role of Green Tea Catechins” by P.L. Janssens et al., Physiol Behav, 8/1/16
By Maria Noel Groves