Green Tea Helps Burn Fat

EGCG Extracted from Green Tea

Its proper use is to amuse the idle, and relax the studious, and dilute the full meals of those who cannot use exercise, and will not use abstinence. 
- Samuel Johnson

Johnson was talking about tea. He was passionate about tea (but not exercise or abstinence) and described himself as a "hardened and shameless tea drinker" - a trait confirmed in James Boswell's celebrated biography of the great man. Little did Johnson know that tea did more than just "dilute the full meals" of which he was so fond. It probably helped burn off some of the fat those meals tended to leave behind.

That conclusion can be drawn from new research indicating that tea - green tea in particular - appears to have value for weight reduction.1 In a study conducted by scientists at the Universities of Geneva and Fribourg in Switzerland, it was found that green tea has a significant thermogenic (fat-burning) effect. This is almost too good to be true, because green tea is already one of the most potent items in nature's arsenal of healthful foods. Surely its cup runneth over!

We will have a look at this ancient and wondrous beverage - and an amazing chemical compound it contains - but first, let's see what those Swiss researchers did.

THE WEIGHT-LOSS STUDY 
After careful screening, ten healthy young men, aged 24-26, were recruited for the study. They ranged from lean to mildly obese (8-30% body fat),* and fat constituted 35-40% of their usual daily energy intake - in other words, a typical Western diet. On a rotating, randomized, double-blind basis at intervals of about one week, the men were given three supplement treatments for one day each. Each treatment consisted of: (1) a powdered green tea extract (in an amount roughly equivalent to four cups of the beverage per day), or (2) an amount of caffeine (which is known to be thermogenic) equal to that found naturally in the green tea extract, or (3) a placebo.

*Average body fat in healthy young men is about 20%, and in healthy young women, 27%. As we age and lose muscle mass, these figures increase to about 30% and 40%, respectively.

During the entire 56-week duration of the study, the men were restricted to a standard weight-maintenance diet consisting of about 13% of energy intake as protein, 40% as fat, and 47% as carbohydrate. For each of the three one-day treatments, the men were confined for 24 hours to a respiratory chamber (the size of a small room) designed to allow precise measurement of their energy expenditure. They took the supplements in three equal doses, with breakfast, lunch, and dinner.

GREEN TEA BURNS FAT 
Compared with placebo, the green tea extract produced a significant increase in total energy expenditure: about 4%. That may not sound like much, but a small effect continued day after day for an extended period would add up. Also, this 4% increase corresponds to a large increase in the thermogenic component of total energy expenditure: about 35-43%. The authors concluded that ". . . oral administration of the green tea extract stimulated thermogenesis [fat-burning] and fat oxidation and thus has the potential to influence body weight and body composition . . . ."Their discovery - the first demonstration of this effect of green tea in a human trial - built upon their own previous laboratory work that led to the same conclusion.2

In the new study, the caffeine alone produced no significant increase in total energy expenditure compared with placebo, presumably because the amount given (150 mg per day) was below its threshold for stimulating thermogenesis. It may well be, however, that the green tea effect was partly due to its caffeine content, through a synergistic interaction between the caffeine and . . . what? Clearly, there must be some other agent in green tea that is primarily responsible for its effect. Far from being a mystery substance, however, this agent is already well known to medical scientists from a different arena entirely: cancer research.

GREEN TEA FIGHTS CANCER 
Green tea holds a place of high honor among nutritional supplements for its role in helping to prevent certain cancers in humans. Well-controlled clinical trials have shown that green tea can prevent cancers of the pancreas, colon, small intestine, stomach, breast, and lung.3 No other supplement can make such a claim.

Although there are many exotic chemical compounds in green tea, one towers above the rest and is considered by some scientists to be among the most promising anticancer compounds ever discovered. It is epigallocatechin gallate(EGCG), and it belongs to a class of chemicals called catechins. These are members of a larger class called polyphenols, which are themselves members of a still larger class called flavonoids. You've heard of flavonoids - they're colorful plant pigments, found in many fruits, vegetables, and herbs, that are noted for their powerful antioxidant properties and a host of documented benefits against cancer, heart disease, vision disorders, allergies, viral infections, and more.

GREEN TEA IS AN ANTIOXIDANT POWERHOUSE
Of all the catechins in green tea, EGCG is by far the most pharmacologically active and, by a stroke of luck, also the most prevalent, accounting for at least half the total polyphenol content. In the Swiss weight-loss study, the dose of green tea extract used was 375 mg of polyphenols per day, of which 270 mg (72%) was EGCG.

EGCG is an antioxidant to be reckoned with. According to researchers at the University of Kansas, the antioxidant power of this compound is about 100 times greater than that of vitamin C and 25 times greater than that of vitamin E in protecting DNA from the kind of free radical damage that is thought to increase the risk of cancer.4

In addition, it appears that EGCG is able to signal cancer cells to stop reproducing by stimulating a natural process of programmed cell death called apoptosis. But it does no harm to healthy cells. Furthermore, EGCG apparently inhibits the production of an enzyme called urokinase, which cancer cells need in order to grow. In animals, blocking urokinase causes tumors to shrink and sometimes sends cancer into complete remission. This may be EGCG's single most valuable function.

The anticancer effects of green tea have been most evident in those parts of the world where it is consumed regularly and in relatively large quantities (typically about five to ten cups per day). For example, epidemiological studies show that in Asian countries, the incidence of prostate cancer is low compared to the West, and green tea consumption is believed to be the reason for the difference.5 Indeed, laboratory studies on the biological effects of green tea have proved that EGCG induces cell death in human prostate cancer cells.6

 

 Epigallocatechin gallate (EGCG), the principal 
source of green tea's thermogenic and other benefits.

 

GREEN TEA FIGHTS HEART DISEASE TOO
Green tea is also known for its protective role against heart disease.7 In studies conducted on rodents, it helps to reduce the levels of lipids (fatty substances), such as cholesterol, in the blood - specifically, the levels of low-density lipoprotein, or LDL (the "bad" cholesterol).8 It also inhibits the oxidation of LDL, thereby reducing LDL's tendency to form the artery-clogging plaques that are implicated in heart attacks. At the same time, it helps to boost the levels of HDL (the "good" cholesterol). And it lowers blood glucose and triglyceride levels, which might indicate an ability to reverse the effects of insulin resistance, a common problem of aging.

WHY MUST IT BE GREEN TEA? 
Green tea (Camellia sinensis) is not a special variety of tea, it's just tea made from very young, downy leaves, which are steamed when fresh-cut, and then rolled and dried to make the commercial tea product. The more common black tea, which is more popular because it is less astringent, is made from the same young green leaves, but they are fermented before being rolled and dried. Oolong tea is an intermediate type that is partially fermented.

Thermogenesis
Thermogenesis is the generation of heat, especially by physiological processes. In our bodies, thermogenesis occurs primarily by a series of chemical reactions in which carbon dioxide and water molecules are produced from fat molecules. The reactions liberate thermal energy - heat - some of which is dissipated to the outside world, along with the carbon dioxide and water. This loss occurs mainly via our lungs, skin, and excretory systems.

Heat can be quantified using a variety of physical units of measure, one of which is the calorie (that's all a calorie is - a unit of measure). Thermogenesis is how calories are "burned."

In the fermenting process, which is oxidative in nature, much of the value of green tea is lost, because enzymes convert many of the polyphenols in the tea leaves to less active compounds. This greatly diminishes the tea's medicinal value. Oxidation is not a problem in green tea because the steaming process inactivates the enzymes responsible for the oxidation. The antioxidant power of green tea is six times greater than that of black tea.3

CAFFEINE AND EPHEDRINE: THE DYNAMIC DUO
Tea derives its astringency from tannins (which are also found in red wines) and its stimulant properties from its caffeine content. As we have seen, caffeine is a thermogenic agent. It is especially effective when combined with the time-honored supplement ephedrine (a natural stimulant and thermogenic agent extracted from the herb ephedra) because of a synergistic effect between these two compounds.9 Caffeine and ephedrine work not only to stimulate thermogenesis but also to suppress appetite. A key benefit of this dynamic duo's action is that it promotes the loss of fat but not of lean muscle. 

There are also thermogenic 
supplements to help boost 
energy expenditure, and they are 
more likely to have long-lasting 
benefits than any diet.

The addition of green tea's amazing polyphenol EGCG to this already potent combination promises to make it even better. And that's good news, because . . .

WE'RE TOO FAT! 
Obesity is epidemic in the United States, despite a culture that seems to worship the idea, at least, of physical fitness. But just look at any typical crowd of Americans, and you'll see tons of fat. We're not the only country with fat people, of course, but we are the champs. Many visitors from other countries can scarcely believe their eyes when they see all that fat - even in our schoolyards, which is really alarming, because those hapless kids are being set up for a life of serious medical problems.

For practical purposes, obesity can be defined in at least three ways:

  1. Being more than 20% above the normal, desirable weight for one's height.
  2. Having more than 25% body fat (for men) or more than 30% (for women).
  3. Having a body mass index (BMI) of 30 or more. BMI is calculated by dividing your weight in kilograms by the square of your height in meters. In English units, divide your weight in pounds by the square of your height in inches, then multiply the result by 703.

Another window on the problem is our waist/hip ratio (WHR), which indicates where we're carrying our excess fat. Too much around the middle is a definite risk factor for disease or disability. Measure your waist, measure your hips at the widest point, and then divide the waist by the hips. For men, a WHR of 1.0 or greater is the red zone; for women, it's 0.8 or greater.

HOW BAD IS IT? 
Very bad. Obesity is shaping up (so to speak) as a major medical crisis of the twenty-first century, according to many public health experts. We're getting fatter all the time, despite our knowledge of the consequences. There is overwhelming evidence that obesity - and, to a lesser extent, merely being overweight (BMI = 25-29) - is directly or indirectly responsible for our susceptibility to many serious diseases that degrade or ruin our lives while we are alive, and kill us before our time. These diseases include cancer, cardiovascular disease, diabetes, degenerative joint diseases, psychological disorders such as depression, and more. (Not to mention that most people see obesity as unattractive and unsexy - perhaps they subconsciously equate it with poor health.)

A Brief History of Tea
Tea has been grown in China since prehistoric times and is the most widely consumed beverage on earth, other than water. By the eighth century A.D., tea was a commercial product in China. Tea drinking had become popular, in part because a hot drink made with boiled water was found to be much safer than plain water, which might be contaminated and cause disease. Tea also came to be valued for its alleged medicinal properties.

It was as a medicine, in fact, that tea was introduced to Japan in 805 by a priest named Saicho, who had spent three years visiting Chinese Buddhist temples on orders from the emperor. Then in 1191, another priest, Aeisai, returned from a visit to China and introduced Japan to Zen Buddhism. He also brought a renewed dedication to tea and planted tea seeds widely. He published medicinal claims for tea in 1214.

The tea ceremony, or chanoyu - the ritual preparation, serving, and drinking of tea - was introduced in Japan in 1484 by the shogun Yoshimasa. Although his reign was otherwise disastrous, he was known for encouraging the arts, and the elegant tea ceremony has survived as a cherished part of Japanese culture. It is a celebration of good taste, in every sense, that honors this humble yet wondrous brew.

The first mention of tea in English appeared in 1597 in a translation of the journals of a Dutch navigator, who called the beverage chaa.

Put simply, obesity equals accelerated aging, needless suffering, and premature death - not in every case, of course, but statistically. (Hippocrates, the "father of medicine," was the first to put on record that fat people don't live as long as thin people.) If you're a nonsmoker and are obese, the number one thing you should do to preserve your health and prolong your life is lose weight. (If you're a smoker, losing weight is number two; you know what number one is.)

DIETS DON'T WORK 
Most diets, especially fad diets, are spectacularly unsuccessful in the long run, especially if they're not accompanied by plenty of exercise as a way of life (diet without exercise is useless). That does not mean that we shouldn't bother to watch what we eat. Of course we should! We should eat a healthy diet (which is not the same as being on a diet) and get plenty of exercise. There are only two ways to lose weight: reduce energy intake or increase energy expenditure.** The former means eating less (in terms of caloric value), which is tough. The latter means exercising more, which can be tough too. But . . . there are also thermogenic supplements to help boost energy expenditure, and they are more likely to have long-lasting benefits than any diet.10

** Actually, there is a third way: grow old. Your brain will gradually lose weight, whether you like it or not. Sorry!

References

  1. Dulloo AG, Duret C, Rohrer D, Girardier L, Mensi N, Fathi M, Chantre P, Vandermander J. Efficacy of a green tea extract rich in catechin polyphenols and caffeine in increasing 24-h energy expenditure and fat oxidation in humans. Am J Clin Nutr 1999;70:1040-5.
  2. Dulloo AG, Seydoux J, Girardier L, Chantre P, Vandermander J. Green tea and thermogenesis: interactions between catechin-polyphenols, caffeine, and sympathetic activity. Int J Obes Relat Metab Disord 2000 Feb;24(2):252-8.
  3. PDR for Herbal Medicines, 2nd ed. Medical Economics Co., Montvale, NJ, 2000, p 370.
  4. Kalyn W, ed. The Healing Power of Vitamins, Minerals, and Herbs. The Reader's Digest Association, Pleasantville, NY, 1999, p 311.
  5. Gupta S et al. Prostate cancer chemoprevention by green tea. Semin Urol Oncol 1999 May;17(2):70-6.
  6. Paschka AG, Butler R, Young CY-F. Induction of apoptosis in prostate cancer cell lines by the green tea component (-)-epigallocatechin-3-gallate. Cancer Lett 1998;130:1-7.
  7. Stensvold I, Tverdal A, Solvoll K, et al. Tea consumption. Relationship to cholesterol, blood pressure, and coronary and total mortality. Prev Med 1992;21:546-53.
  8. Vinson JA, Dabbagh YA. Effect of green and black tea supplementation on lipids, lipid oxidation, and fibrinogen in the hamster: mechanisms for the epidemiological benefits of tea drinking. FEBS Lett 1998;433:44-6.
  9. Toubro S, Astrup A, Breum L, Quaade F. Safety and efficacy of long-term treatment with ephedrine, caffeine, and an ephedrine/caffeine mixture. Int J Obes Relat Metab Disord 1993;17:S69-72.
  10. Toubro S, Astrup A. Randomized comparison of diets for maintaining obese subjects' weight after major weight loss: ad lib, low fat, high carbohydrate diet v. fixed energy intake. BMJ 1997;314:29-34.