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Green Tea

Renee Hanemann

October 24, 2008


For the past few decades, the United States has been struck with a severe epidemic, affecting a large portion of the population.  The epidemic in question is the obesity epidemic, leading to a drastic increase in the number of cases chronic diseases caused by obesity in the United States.  This is especially apparent in the increase in obesity among American children.  In fact, children today are being diagnosed with type two diabetes mellitus, which was, in years past, strictly found in adults (Volpe 2006).

What is the purpose of learning about green tea?

Because of America’s ever-growing waistline, people are constantly trying to lose weight.  In a culture where a fast pace is ideal, people are used to getting results quickly.  This is reflected in America’s diet industry: numerous weight loss fads claiming to shed the most pounds in the shortest period of time. :::Desktop:images.jpegPaired with pictures of fit, beautiful people and testimonies of quick weight loss with little to no work, these fads have gained popularity.  One of the most popular fads is the use of supplements and diet pills (Volpe 2006).  These are often expensive and sometimes harmful.

One of the most common elements in weight loss plans is green tea.  Green tea extract is used in numerous diet pills and fat burning supplements, claiming to significantly boost metabolism and aid in weight management.  It is common knowledge that the most effective way to lose weight is a combination of proper diet and regular exercise, but is it possible that the use of green tea is a healthy substance to expedite the weight loss process? Or is it just another money-eating hoax of the diet industry?

How does green tea work on the metabolic process?

Although fairly new to American culture, green tea leaves have been consumed for half a million years in India and China (Bell and Goodrick, 2002). Green tea is produced from the leaves of the Camellia Sinensis, a plant found in Asia and Africa.  It is made by steaming the leaves of the plant, preserving the polyphenols and flavonoids, which retain much of the antioxidants of the drink (  In fact, these polyphenols are the core reason for green tea’s reputation for weight loss stimulation, as they boost the fat burning process by creating excess heat in the body through thermogenesis (Dulloo, et al., 1999). 

The polyphenols are subcategorized into six catechin compounds; the most active catechin in green tea is epigallocatechin gallate (EGCC) (Westerterp-Plantenga, Lejeune, and Kovacs, 2005).  The excess of EGCC in green tea is believed to enhance the production of norepinephrine, a hormone used by the sympathetic nervous system to release stored energy from fat (Dulloo, et al., 1999).  The caffeine in green tea also stimulates thermogenesis, but the thermogenic properties of green tea greatly outweigh that of caffeine (Westerterp-Plantenga, Lejeune, and Kovacs, 2005).  The flavonoids in green tea also restrict the enzyme catechol O-methyl-transferase (COMT), which is the enzyme that restricts norephinephrine (Bell and Goodrick, 2002).  Now, norephinephrine is able to act freely on the metabolism and fat oxidation.  Green tea’s composition of polyphenols and caffeine exercises a thermogenic result, aiding in fat oxidation and speeding up the metabolic process.

What claims are being made about the effect of green tea on metabolism?

Millions of people across the nation are constantly trying to lose weight, and many of them turn to supplements and pills to aid this process.  Since green tea has such an evident effect on metabolism, many of these supplements contain green tea extract, advertising its ability to burn fat quickly.  The Internet is littered with these advertisements, complete with pictures and testimonials praising the safe and natural way to lose weight, sans exercise.

One website advertises the Avatrim Green Tea pill with the bold headline, “The Painless, Risk-Free Way to Get the Sexy Body You Want for Good without Dieting or Exercising” (  :::Desktop:kubrickheader.jpgAccording to this website, this “miracle pill” simultaneously curbs the appetite while burning fat and stimulating energy.  There is also the added bonus of retaining muscle mass without lifting weights.  In one paragraph, it mentions liquid green tea, “probably you have tried drinking green tea on a regular basis but now you want something more effective” (  Personal testimonies claim that because of this pill, they not only feel healthier, but they are no longer hungry.  :::Desktop:free_trial.jpg

Another website advertises the Mega-T Green Tea Diet Pill.  They stress the fact that it has no dangerous side effects because it has no ephedrine and only a small amount of caffeine (  The Mega-T Green Tea Diet Pill advertisement seems more legitimate than the Avatrim one because the former goes into detail about how exactly it works, defining thermogenesis and giving a detailed explanation of the composition of green tea.  It also provides links to other websites for further reading on green tea.  Although this may seem like a plausible supplement, it is clear that the advertisement is a blatant exaggeration of the effects of the diet pill; scientific research states the benefits of green tea on health are apparent, but it has not been proven to burn copious amounts of fat.   :::Desktop:images-1.jpeg

When reviewing these products, it is essential to keep in mind that the claims that these websites make are not always reliable.  They usually have little to no evidence, and the testimonials are often fabricated.  More often than not, these products are merely a hoax to get people to spend money on a worthless and possibly dangerous product.

What evidence is offered in support of these claims? Who is offering it?

One specific scholarly article described a study in which ten healthy young men, ranging from lean to slightly overweight, were randomly given one of three meals, each containing either green tea extract, a caffeine capsule, or a placebo capsule (Dullo et. Al, 1999).  Then they spent twenty-four hours in a respiratory chamber where their energy expenditure and thermogenesis was measured.  The results were that the green tea raised metabolic rates and sped up the fat burning process, and the caffeine was just a confounding variable. 

The University of Chicago’s Tang Center for Herbal Medical Research on epigallocatechines did a study on mice that found that consumption of green tea reduced the blood glucose level, lipids, and cholesterol of the animals.  Furthermore, fat deposits under the skin are also reduced (  Although this seems like great news, it is important to keep in mind that the results may not be similar in humans.

Apart from the superficial claims of the diet industry, scientists have done experiments to produce concrete evidence that green tea does, in fact, stimulate metabolic rates and produce health benefits, if only slightly.

Is green tea effective in weight loss?      :::Desktop:images-3.jpeg

Half a million years of use has determined the legitimacy of the effect of green tea leaves on metabolism and health.  It has been scientifically proven that green tea contains certain polyphenols that stimulate specific hormones that affect fat burning.  However, in the diet-crazed society that we live in, industries are using green tea extracts as one of many ingredients of pills and supplements.  These supplements are often expensive and ineffective, and sometimes dangerous.  Green tea in itself, as a drink prepared from the leaves of the Camellia Sinensis plant, has undeniable effects on health and metabolism; however, when it is extracted and placed in a diet pill, one should be more wary of its results.  Also, while green tea has components that speed up metabolic rate and stimulate fat oxidation, it is not a sufficient means to lose a tremendous amount of weight.  A proper diet combined with regular exercise is needed in order to properly shed fat.

















Bell, S.J, & Goodrick, G.K. (2002). A functional food product for the management of

weight. Critical Reviews in Food Science and Nutrition, 42(2), 146-174.

Dulloo, A., Duret, C., Rohrer, D., Girardier, L., Mensi, N., Fathi, M., Chantre, P., &

Vandermander, J. (1999). Efficacy of a green tea extract rich in catechin

polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation

in humans. American Journal of Clinical Nutrition, 70(6), 1040-1045.

Volpe, S. L. (2006). Popular Weight Reduction Diets. Journal of Cardiovascular

Nursing, 21(1), 34-39.

Westerterp-Plantenga, M.S., Lejeune, M.P, & Kovacs, E.M. (2005). Body weight loss

and weight maintenance in relation to habitual caffeine intake and green tea supplementation. Obesity Research, 13, 1195-1204.



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