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Green Tea: The Dieting Girl’s New Best Friend?

Sarah Clinton

March 4, 2009

Obesity is not a new phenomenon, by any means. However, it is only within the past few decades that obesity has grown to the current epidemic proportions in the American population, especially. To counteract this, a plethora of diet aids, workout gimmicks, and fad “healthy lifestyle” programs have popped up in our magazines, television ads, and internet news. Here, I investigate the safety and effectiveness of one of those “magic fat burners,” specifically green tea and its relation to weight loss.

Obesity Risks and Statistics

                An obese person is defined as a person having a Body Mass Index (which is calculated by relating weight to height) of 30 or higher. Currently, 34% of American adults are considered obese, and approximately 6% of these are considered “morbidly obese” ( Unfortunately, there is a myriad of health problems that are associated with obesity, including hypertension, osteoarthritis, high cholesterol, Type II Diabetes, heart disease, stroke, gallbladder disease, sleep apnea, and several types of cancer (

                Most obese people have not been so their entire life. On the contrary, most of them gained the weight gradually through years of making poor choices in relation to diet and exercise. The average American gains between one and two pounds a year; after fifteen or twenty years, a healthy person could easily become dangerously overweight ( Since America is a very fast-paced society, it does not often leave room for the working adult to eat a healthy, nutritious meal. As a result, fast food is a very popular, very fattening choice for dinner. To compound this problem, we live in the “Super-size me” era, where portion control is nearly unheard of. When this is added to the daily stress adults encounter at the workplace and at home, which prompts emotional eating, we are left with a prime recipe for disaster.

Green Tea Claims

                Especially for the past few years, green tea has been cited as a safe, effective method that people can use to shed unwanted pounds. Advocates of green tea use extol its high concentration of antioxidants called polyphenols, which help to annihilate cancer-causing free radicals and may help to reduce LDL (or “bad”) cholesterol. The catechins found in green tea have been shown to increase thermogenesis, which is the process of heat production in mammals, resulting in fat loss. Caffeine is also contained in green tea, and has been linked to increased metabolism and additional weight loss. When metabolism is increased, the body burns more calories even when at rest. In fact, in a study reported in the American Journal of Clinical Nutrition, participants in the study had an extra 4% energy expenditure in a twenty-four hour period after drinking green tea. And, much to the joy of thyroid patients, green tea safely produces an increased metabolism without overstimulating the adrenal glands (

Research and Studies

                A placebo controlled double-blind human clinical trial headed by the Professor Emeritus Department of Nutritional Sciences from the University of Toronto sought to determine whether the consumption of green tea extract for a twelve-week period would result in a significant loss of body weight. The thirty-four human subjects, all of which were over the age of thirty and had a BMI of 25 or greater, were randomly assigned to either the placebo group or the group set to consume the green tea supplements. Of the placebo group, sixty percent gained weight or had no change in body weight. However, in the set of adults who took the supplements, seventy percent either lost weight or saw no change in body weight (

                Scientists at the University of Chicago’s Tang Center for Herbal Medicine Research tested the effects of epigallocatechin gallate (EGCG), a major chemical component of green tea, on the body weight of rats. Rats that were injected with EGCG, which is derived from green tea leaves, lost their appetites and consumed up to sixty percent less food than normally after seven days of injections. This caused them to lose an astonishing twenty-one percent of original body weight. However, EGCG was largely ineffective when administered orally, even after fourteen days. Long-term ingestion may mimic the effects that injection produced, but humans should not expect to lose as much weight as the rats that received the EGCG injections. To even come close, people would have to guzzle green tea down almost constantly. This is not advisable, since consumption of green tea in large doses caused a decrease in insulin and testosterone in the rats; this effect has not been studied in humans (

                In findings published in the American Journal of Clinical Nutrition, Dulloo, Duret, Rohrer, Girardier, Mensi, Fathi, Chantre, and Vandermander (1999) investigated whether green tea extract could reduce energy expenditure and fat oxidation over a twenty-four hour period, as a result of its caffeine content and catechin polyphenols. The subjects of study were ten healthy men, who were randomly assigned to ingest either green tea extract, caffeine, or a placebo, at breakfast, lunch, and dinner. Relative to subjects taking the placebo, participants who consumed the green tea extract experienced a four percent increase in energy expenditure. Participants consuming caffeine in levels relative to the amount of green tea consumption in the other group experienced no increase in energy expenditure. Researchers concluded that green tea does indeed have thermogenic properties and promotes the oxidation of fat beyond a level that can simply be explained by the presence of caffeine.

Is it worth it?

                In every study that I found that was conducted on green tea, the final conclusion has been that green tea does indeed have a profound effect on weight and fat loss. It has been found to have thermogenic properties, and is proven to increase the resting metabolic rate. Long-term effects of regularly drinking green tea include lowered cholesterol, a lower body weight and BMI, as well as a lowered risk for various types of cancers. As of yet, there have been no discovered adverse effects to incorporating green tea into a person’s lifestyle. To use, it is suggested that a person drink three to five cups of green tea a day, perhaps morning, noon, and night.



Discussion of Sources

                The vast majority of the articles I used to compile this report are from universities, hospitals, and medical journals. The purpose of these institutions publishing findings such as this is to educate the public and enhance the health of the people. Therefore, it is safe to say that the information presented is highly accurate and reliable. The studies conducted were done so in a professional manner, and were validated and approved before being published to journals such as the American Journal of Clinical Nutrition, which is highly respected and very prestigious. Each of the experiments ended with extremely similar results, resulting in an iron-clad consensus that the claims made by green tea enthusiasts are indeed valid.

Should YOU use green tea to lose weight?

                In conclusion, after careful assessment of the sources and shrewd examination of the results, it is my personal opinion that green tea is safe to use either as an accessory to a weight loss plan or even just to add to a normal dietary routine. As always, if a person has a special medical need, he or she should speak with a doctor to assess whether or not this weight loss method is appropriate.


However, barring any extraordinary cases, I believe that the general population could greatly benefit from adding green tea to its daily food intake. Green tea is inexpensive and takes next to no time to prepare, and even less to consume as a supplement. This is a good fit for people that have time constraints and those that have no desire to exercise. Even more than firing up metabolism, green tea provides plenty of antioxidants, which should promote greater health for anybody and everybody. So, if you are one of those people who is tired of being constantly bombarded and tempted by gimmicky workout infomercials, add green tea to your diet. It is safe, easily obtained, and most importantly, effective.





Literature Cited


Andrews, K., Rao, V. (2005) New Research Offers Weight Loss Solution: Green Tea and CLA


Collins, Karen. (2007) Avoiding Adult Weight Gain. American Institute for Cancer Research


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. The American Journal of Clinical Nutrition.


Erlich, S., Hawkins, E. (2008) Green Tea. University of Maryland Medical Center.


Liao, S. (2000) Green tea derivative causes loss of appetite, weight loss in rats. The University of Chicago Medical Center


Roy, H.J., Lundy, S. (2007) Green Tea Metabolic Influences. Pennington Nutrition Series, Article 9.


Shomon, M. (2003) Green Tea Extract Increases Metabolism, May Aid in Weight Loss.



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