Green Tea and Weight Loss

Long revered for its ability to increase blood flow, neutralize toxins, improve resistance to disease, and enhance urine flow, green tea has caught the attention of many consumers for its weight-reducing power. And for good reason—the science behind green tea is confirming what the Chinese have known for more than 4,000 years.
How It WorksIf there’s a single, primary mechanism behind green tea’s effect on weight loss, researchers haven’t yet agreed on it. For example, green tea appears to act on several tissues (fat, muscle, liver, intestines) and, as a result, can increase the rate at which we burn calories, preferentially increase fat oxidation, increase glucose uptake in muscle, and decrease glucose uptake in fat. In addition, scientists have shown that green tea slightly reduces fat and carbohydrate absorption by inhibiting gastric and pancreatic lipases as well as the activity of amylase and sucrase (different types of enzymes). Finally, molecular biologists are now uncovering evidence that green tea may also act on key genes to inhibit increases in fat cell size and number. From a scientific perspective, this myriad of potential mechanisms makes green tea all the more intriguing.
In the real world, green tea is usually consumed as a powdered extract or as a beverage. Studies have uncovered a unique interaction between caffeine and green tea’s other components that makes them an effective means of enhancing body composition. In a nutshell, caffeine inhibits an enzyme called phosphodiesterase, which normally breaks down molecules that enhance intracellular energy production. EGCG (the major component in green tea polyphenols) inhibits a different enzyme called COMT (catechol-O-methyl-transferase) that breaks down the “fight-or-flight” hormone noradrenalin, prolonging its thermogenic activity in the body. Thus when caffeine and EGCG are combined—bang!—both enzymes are inhibited and energy use is increased dramatically.