Read an Excerpt
Sip Your Fat Away
*EGCG (Green Tea Extract)
We humans drink more tea than any other liquid, except for plain old H2O. And Bill Gottlieb does his part to keep tea number two.
Every morning before work, he makes himself a big pot of green tea (we’ll talk in a minute about the differences among the three main types of tea—black, green, and oolong), and whether the variety he chooses is gunpowder, dragon well or sencha, his daily ritual is always the same.
He fills a kettle with water and puts it on the stove to boil…spoons tea leaves into a mesh tea ball …places the tea ball in a ceramic teapot…fills the pot when the water boils …puts the pot on a tray…and carries the tray to his office, where he blissfully sips away while reading the morning paper.
And here are a few more tea-dious details about Gottlieb: he’s fifty–three, five foot ten, and weighs 154 pounds—the same weight as when he graduated from high school.
Does drinking green tea every day for so many years have something to do with the fact that he’s not suffering from middle–aged spread? A bunch of scientists in Taiwan might think so.
TEA DRINKERS ARE 20 PERCENT TRIMMER
This was the startling news published in the September 2003 issue of Obesity Research by Dr. Chih–Hsing Wu and a team of Taiwanese scientists at the National Cheng Kung University Hospital. They had studied more than one thousand men and women, with an average age of forty–eight, querying them about numerous “lifestyle characteristics.”
Did they smoke? Drink alcohol? Coffee? What were their favorite foods and how often did they eat them? How much did they exercise? How much money did they make? And…how much tea did they drink a day, and for how many years had they been doing so?
But the researchers didn’t only investigate habits. They also looked into hips. Specifically, they measured each person’s percentage of body fat, and their waist–to–hip ratio, or WTHR. (WTHR is your waist measurement in inches, divided by your hip measurement. It not only shows the size of your belly, but also indicates how healthy you are: people who have a higher WTHR, storing more fat in their tummies, are at a greater risk for heart disease than people who store more fat in their hips and thighs.) The results from the Taiwanese study were remarkable.
Of those studied, 43 percent had been “habitual” tea drinkers for ten years or more, drinking about 15 ounces of tea a day.
The habitual tea drinkers had, on average, 19.6 percent less body fat than people who didn't drink tea regularly.
They also had slimmer waists, with a 2.1 percent lower WTHR.
No other lifestyle factor—whether or not they were smokers, snackers, sedentary or high–salaried—correlated with a lower percentage of body fat. Tea was the likely ticket to leanness.
And only a few of those trimmer tea drinkers were regularly drinking Earl Grey, English Breakfast, or another variety of black tea. Eighteen of the habitual tea drinkers drank black tea. Four hundred fifty–five drank green or oolong. What's so special about those two varieties? To find out, let’s take a quick trip to a tea plantation.
GREEN TEA: LEAVING THE GOODNESS IN THE LEAVES
Black, green, and oolong tea all start the same way: as leaves on Camellia sinensis, an evergreen shrub that can grow to the height of a tree but is cultivated as a bush on tea plantations. A few times a year, the buds and the tender, young leaves at the top of the bush are picked and then dried on racks. But those dried tea leaves aren't ready for the teapot.
The next step is fermentation, as enzymes begin to break down other natural chemicals in the leaf. In black tea, fermentation is allowed to do its thing, producing a darkly colored, robustly flavored tea. But in green tea, fermentation is brought to a halt by heating: after drying, the leaves are lightly steamed or gently pan-fried in huge woks. Oolong tea is midway between black and green: a degree of fermentation is allowed to occur before the leaves are heated.
This seemingly slight difference in processing creates an enormous difference in the chemical composition—and the potential impact on your health—of green tea as compared to black. That’s because the natural chemicals preserved in green tea leaves are a group of polyphenols containing flavonoids called catechins.
Let's define that trio of terms.
Polyphenols: Super-Protective Plant Chemicals
Polyphenols are polypopular—they get a lot of press. When you read about the health-giving power of the red in wine, the dark in chocolate, or the green in tea, you're reading about polyphenols. Plants produce polyphenols not because they want human beings to be healthier, but for their own protection: polyphenols are antioxidants, shielding plants from environmental harm.
A flavonoid is a type of polyphenol. There are five thousand of them, like the quercitin in kale, the anthocyanins in blueberries, and the genistein in soy.
Catechins (pronounced CAT-uh-kins) are a type of flavonoid found in high levels in green tea. (Green tea consists of 30 to 42 percent catechins, while black tea has 3 to 10 percent, with oolong in between.) Catechins aren’t your everyday antioxidant: they’re more powerful than antioxidant vitamins like A, C, and E in stopping the “free radical” damage to cells that can trigger chronic disease and speed aging. But that’s not all catechins do.
In study after study in cell cultures, animals, and humans, they have been shown to help prevent, slow, or kill cancer cells—colon, breast, prostate, lung, skin, and others.
They can lower cholesterol, perhaps helping prevent heart disease. Ditto for high blood pressure.
They can lower blood sugar, perhaps helping prevent diabetes.
They can strengthen the immune system, helping to defuse viruses.
They can reduce inflammation, a harmful process linked to a host of diseases, from Alzheimer's to ulcers.
And—most important for this book—they can help burn calories and defuse fat making.
Scientists have isolated several catechins in green tea. But it's epigallocatechin gallate, or EGCG—the most abundant catechin in green tea—that we fat fighters are particularly interested in. An extract of green tea that contains high levels of EGCG may help you lose weight. And keep it off.
EXTRACT = EX-FAT
Let's move our green tea party from Taiwan to Switzerland. There, in 1999, Dr. Abdul Dulloo and his team of researchers at the University of Fribourg conducted an experiment on ten healthy men, publishing their results in the American Journal of Clinical Nutrition.
On three occasions, the men stayed for twenty-four hours in a “respiratory chamber”—an airtight room with all the comforts of a hotel (bed, armchair, table, TV, VCR, telephone, sink, and toilet). But this “hotel room” was inside a laboratory, where equipment measured differences between the air pumped into the respiratory chamber and the air pumped out, allowing researchers to calculate the exact amount of calories and fat the men burned while living in the chamber. During each of the three twenty-four-hour periods the men spent in the respiratory chamber, they took a particular set of pills with their breakfast, lunch, and dinner: (1) 50 milligrams (mg) of caffeine, (2) a combination of 90 mg of EGCG and 50 mg of caffeine, the amount of EGCG and caffeine in a cup of green tea, or (3) a placebo. The results?
The men burned a lot more calories when they took the EGCG/caffeine combo, compared to either the caffeine pill or the placebo—an average of 78 more calories over the twenty–four hours they spent in the chamber. The men also burned about 20 percent more fat on the EGCG/caffeine combo. How did the green tea extract incinerate extra calories and fat?
Dr. Dulloo theorizes that EGCG blocks the action of an enzyme that breaks down noradrenaline (NA), a hormone manufactured by the adrenal gland. NA functions as a neurotransmitter in the brain, stimulating the sympathetic nervous system, which controls heart rate, muscle tension, and the release of energy from fat. So when you take EGCG, the body’s dominoes may fall like this:
EGCG keeps more NA in your brain…that extra NA triggers your metabolism to stay more active, thereby burning more calories…and the boost in NA also triggers extra fat burning.
Caffeine lends this process a helping hand, says Dr. Dulloo, blocking other enzymes that affect NA.
To add more evidence to their theory, Dr. Dulloo and his team measured the men’s urinary levels of NA during each of the twenty–four hours they were in the respiratory chamber. And, sure enough, when the men took EGCG/caffeine supplements, their NA levels were higher than when they took either caffeine alone or the placebo.
Dr. Dulloo’s conclusion: a green tea extract consisting of EGCG and caffeine has the potential to help people lose weight and fat. And he has another important opinion.
It’s theorized that people who eat extra fat but don’t burn extra fat (through increased exercise or some other means) develop a disordered appetite, craving and overeating fatty and other high–calorie foods. By burning fat, says Dr. Dulloo, a green tea extract may also help control the appetite of a person who typically eats a high–fat, high–calorie diet.
How Much ECGC Is Best?
The scientists in Switzerland aren't the only ones to have found that green tea extracts can burn extra calories and fat. A similar study was conducted by Dr. Sonia Berube–Parent and her team of researchers at Laval University in Canada and published in the British Journal of Nutrition in 2005.
The Canadian scientists wanted to answer two questions: Could they produce the same results as those from Switzerland—would an extract of EGCG/caffeine burn extra calories and fat? And if it did, what dose of EGCG/caffeine would work best?
To find out, the researchers studied fourteen healthy men, aged twenty to fifty, testing them on five separate days in a metabolic chamber (similar to a respiratory chamber). While in the chamber, the men took supplements three times a day that contained 200 mg of caffeine (from the herb guarana) and one of four different levels of EGCG: 90, 200, 300, or 400 mg. A few of the men took a placebo.
The answer to the first question was a qualified yes: the EGCG/caffeine extract increased calorie burning by an average of about 180 calories a day, compared to the placebo. But (unlike what happened in most of the other studies discussed in this chapter) it didn't boost fat burning. (Hey, one out of two ain't bad, especially when it's 180 calories a day—an amount of calories that could help you shed twenty-two extra pounds a year. Plus, many other studies have shown fat burning.)
The surprising answer to the question about dosage: 200, 300, and 400 mg doses did not burn any more calories than the 90 mg dose. Therefore, says Dr. Berube–Parent, it’s likely that 270 mg a day of EGCG is the “optimal concentration” to produce calorie burning.
She also points out that the EGCG/caffeine mixture didn't speed heart rate or significantly boost blood pressure levels—the cardiovascular symptoms experienced by some users of the now-banned ephedra, which also works by stimulating the sympathetic nervous system. (In fact, average blood pressure went up by only one point, from 122/74 to 123/75.)
Her final thoughts: An EGCG/caffeine mixture should be considered as a good addition to a weight-loss program, particularly one that includes nutritional smarts and regular exercise.
We couldn’t agree more.
French Women Do Lose Weight
The studies in the respiratory and metabolic chambers were conducted over several twenty-four-hour periods. But what would happen if someone took a green tea extract for weeks or even months?
To find out, scientists in France studied sixty-three overweight women and seven overweight men for three months, giving them a green tea extract. Their results, published in the journal Phytomedicine, were very positive.
After three months on the extract, the group’s average weight loss was 4.6 percent. And their waistlines shrunk by 4.5 percent.
Like the Canadian researchers, the French scientists note the people taking the supplement had no average increase in heart rate or blood pressure. A green tea extract, they conclude, might be a suitable natural supplement for people who are overweight, supporting their attempt to lose weight.
You won't hear us arguing with them.
Green Tea Extract and Exercise: Double Trouble for Fat
What happens when you take a green tea extract and you exercise? If you’re a mouse that’s been eating a high–fat diet, you lose a lot of weight. That was the finding of a team of Japanese scientists, reported in the journal Medicine and Science in Sports and Exercise in November 2005.
First, the researchers fed mice a high–fat diet. Next, they put the animals on one of three different regimens: exercise; green tea extract (GTE); or GTE and exercise.
The group of exercising mice lost 24 percent of that added weight.
The group of mice given GTE lost 47 percent of the weight they had gained.
But the group of mice that got GTE and exercised lost 89 percent of their extra pounds. (Okay, ounces.)
A similar study, reported in the October 25, 2005 issue of the International Journal of Obesity, produced the same results.
The researchers’ conclusion: “The intake of tea catechins, together with regular exercise, helps to reduce diet-induced obesity.”
It’s great to know that a supplement you’re taking to help you with weight loss may also boost the positive, pound-shedding effect of exercise.
Not Just Losing Weight but Keeping it Off
Another study shows that a green tea/caffeine extract may have an important role after you’ve lost weight—in helping keep the weight off. The experiment, conducted by Dr. Margriet S. Westerterp and her colleagues at Maastricht University in Holland, was published in the scientific journal Obesity Research. She studied seventy–six overweight men and women for four months. For the first month, they ate a very low–calorie diet, losing an average of 13 pounds. For the next three months, they ate a diet aimed at maintaining their weight loss. During that time, a group of the former dieters took an EGCG/caffeine supplement three times a day, before meals, for a total intake of 270 mg of EGCG and 150 mg of caffeine. Another group got a placebo. They were the unlucky group.