In a study reported on in the American Journal of Clinical Nutrition, it was found that green tea extract resulted in a significant increase in energy expenditure (a measure of metabolism), plus also had a significant effect on fat oxidation.
While some of the effects were originally theorized to be due to the caffeine content of green tea, the researchers discovered that the tea actually has properties that go beyond those that would be explained by the caffeine.
The same amount of caffeine as was in the green tea, administered alone, failed to change energy expenditure in other studies. This led reseachers to believe that there is some interaction going on with the active ingredients of green tea that promotes increased metabolism and fat oxidation.
The researchers indicated that their findings have substantial implications for weight control. A 4% overall increase in 24-hour energy expenditure was attributed to the green tea extract, however, the research found that the extra expenditure took place during the daytime. This led them to conclude that, since thermogenesis (the body's own rate of burning calories) contributes 8-10% of daily energy expenditure in a typical cubject, that this 4% overall increase in energy expenditure due to the green tea actually translated to a 35-43% increase in daytime thermogenesis.
Of critical importance to thyroid patients is the fact that none of the research subjects reported any side effects, and no significant differences in heart rates were noticed. In this respect, green tea extract is different from some of the prescription drugs for obesity, and herbal products like ephedra, which can raise heart rates and blood pressure, and are not recommended for many individuals, in particular, those with thyroid disease who may be particularly sensitive to stimulants.
If you were to incorporate green tea into your weight loss efforts, how is the best way to go about it?
One way would be to choose a reputable brand of organic green tea at a health food store or natural grocery, and start by taking a cup of tea every day. You can also take a green tea extract, in the form of a supplement.
Either way, says dietitian Lynn Moss, M.S., R.D., a continuing education specialist for Pharmavite, you should take the green tea with meals, to reproduce the study's conditions as much as possible.
Moss also feels that green tea may be a good choice for thyroid patients because, unlike caffeine, " green tea has the potential to accelerate metabolism -- which can help weight loss slightly -- without overstimulating your adrenal glands."
