Green tea has many health benefits and more and more studies are showing that consumption of green tea or its extracts may assist with weight loss. Green tea has been shown to promote weight loss in animal studies. There have been few studies in humans investigating green tea’s effect on weight loss, but results suggest that green tea might promote weight loss in humans, too.
Green tea is produced from the plant Camellia sinensis, and next to water, green tea is the second most consumed drink in the world. Some of green tea’s health benefits have been known for centuries. Green tea contains powerful antioxidants called polyphenols and flavanols, which help fight inflammation and cancer. The polyphenols in green tea are called catechins, and the most powerful catechin in green tea is called epigallocatechin gallate or EGCG.
Some studies performed in both animals and human support the claims that consumption of green tea may aid in weight control.
Green Tea Weight Loss
Green tea appears to improve body composition through several mechanisms. It inhibits fat cell growth, decreases body fat, and inhibits absorption of fats. EGCG appears to play a role in these mechanisms. EGCG also appears to regulate the genes involved in insulin and glucose metabolism. Green tea is thought to lower blood levels of insulin and glucose, which contributes to weight gain, but a study in humans in Nutrition Journal published in 2010 showed no glucose or insulin lowering effect of green tea, but green tea did provide increased satiety and fullness.
Boosting Metabolism with Green Tea
Green tea stimulates metabolism, which leads to weight loss. It does this by virtue of the fact that green tea contains caffeine, which acts synergistically with EGCG. EGCG inhibits catechol-O-methyltransferase. Catechol-O-methyltransferase breaks down norepinephrine. Norepinephrine increases metabolism. By inhibiting catechol-O-transferase norepinephrine is not broken down with green tea consumption, thus increasing the metabolic rate. See “Natural Metabolism Boosters“.
Green Tea: Cutting the Fat Out
Green tea slows down and limits absorption of fats from the meals and increases the amount of fat that is excreted in feces by regulating enzymes related to fat absorption.
Green Tea and Energy
Energy capacity increased substantially in laboratory mice fed green tea extracts. Mice fed green tea extract ran 30% longer than the controlled mice. In a human study, men given EGCG and caffeine increased their energy expenditure over 24 hours by 4% and burned 79 additional calories per day than those not supplemented with EGCG and caffeine. Another study in humans revealed that men supplemented with green tea extract for 3 months experienced a 4.6% decrease in body weight and a 4.5% decrease in waist size.
How Much Green Tea to Consume?
Most studies showing health benefits of green tea involved drinking three to six cups of tea a day. Taking a green tea extract of 500 mg/day is equivalent to consuming 5 or 6 cups of green tea per day. Since drinking that amount of tea is not customary for Americans, taking an extract may be the most convenient way to obtain the potential health benefits of green tea. Green tea extracts of 500 mg/day or less appear to be safe.
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