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Less than zero?

That buzz might be the sound of calories burning, studies suggest. But green tea extract's real-world effects are unproved.

November 27, 2006|Shari Roan | Times Staff Writer

THE shoppers looked skeptical.

"This is the first drink that can actually help you lose weight," sales representative Anthony Monforte said confidently, handing out tiny samples of a new soft drink, Celsius, at a Vitamin Shoppe in Aliso Viejo.

Leslie Bedford and Marsha McDonogh, office workers who had stopped by on their lunch break, took cautious sips. "Hmmm. It does taste like RC Cola," McDonogh said, agreeing with Monforte's description. Sold on the taste -- and especially the promise -- she plunked down $6.99 for a four-pack.

"If it really works, that's great," Bedford said. "Everyone in our office wants to lose weight one way or another."

Beverage makers are counting on it. Stung by falling sales and criticism that sugar-sweetened soft drinks raise the risk of obesity, they're reaching into scientists' laboratories to come up with healthier products -- vitamin waters, sports drinks, fortified juices and now so-called negative-calorie drinks. The drinks, most notably Celsius and Coca-Cola's and Nestle's Enviga, promise to boost metabolism and burn calories.

The key ingredients are green tea and caffeine. Celsius' manufacturer says its particular combination will increase metabolism enough to burn up to 77 calories per 12-ounce bottle; Coke states that three 12-ounce cans of Enviga will burn 60 to 100 calories. Snapple has also introduced green tea beverages, with labels that claim they boost metabolism.

"Consumers are looking for some functional benefit," says John Sicher, editor and publisher of Beverage Digest, an industry trade publication. "They are saying they want their calories to do something for them."

The effects of the green tea drinks go beyond those of caffeine-laden zero-calorie sodas, the manufacturers of Celsius and Enviga say. An antioxidant found in green tea -- epigallocatechin gallate, or EGCG -- significantly increases metabolism, they say. This, in turn, boosts the body's ability to burn fat.

Raising metabolism is more complicated than simply ingesting a chemical that speeds up the heart rate, which often makes users jittery. Though scientists still aren't sure just how EGCG works, some suggest it triggers greater production of a neurotransmitter called norepinephrine, elevating metabolism. Caffeine also raises the metabolic rate, and early research suggests combining EGCG with caffeine is the key to a measurable increase.

The concept is intriguing -- but far from proven, pharmacology experts point out.

"The data are still emerging," says Roger Clemens, a spokesman for the Institute of Food Technologists and an adjunct professor of pharmacy at USC. "They are not convincing."

Jeffrey Blumberg, a senior scientist in pharmacology at Tufts University is similarly skeptical. "In really carefully controlled studies, you can actually find an increase in metabolic rate," he says. "But if the effects are modest, it might be hard to see them in the real world."

Other studies have shown that the antioxidant does have potential to help prevent some types of cancer, they acknowledge, but the effects on metabolism shouldn't be counted on at this point.

Put to the test

The makers of both Enviga and Celsius say they have research to support their weight-loss claims.

In a study of Celsius, which contains five to 10 calories a bottle depending on the flavor, 20 people were divided into two groups with one group consuming 12 ounces of Celsius and the other group consuming 12 ounces of Diet Coke. The volunteers' metabolic rate was measured before and after consumption. The study showed an average increase of 12% in metabolic rate over a three-hour period among those drinking Celsius compared with a 4% to 6% rise in the Diet Coke drinkers.

Depending on the person's own metabolism (which varies by fitness level, weight, gender and age among other factors), a 12% increase could result in burning up to 77 calories a bottle, says Elite FX, the manufacturer of Celsius, which funded the study. The research was conducted at Ohio Research Group of Exercise Science and Sports Nutrition and was presented last year at a meeting of the International Society of Sports Nutrition.

A study of Enviga, which contains five calories per can, showed that drinking three 12-ounce cans a day increased calories burned by 60 to 100 per day. The study, performed at the University of Lausanne, has not been published.

"The data show the green tea extract appears to enable this gentle boost in the metabolic rate," says Rhona Applebaum, chief scientist of Coca-Cola. "The second mechanism is caffeine. The two together -- what we have found and what other studies have found -- produces this synergy that allows for this gentle boost in rate."

Enviga was launched in October in the northeast United States and will become available nationwide in January. Sweetened with aspartame, it comes in three flavors -- green tea, berry and peach -- and sells for about $1.29 to $1.49 a can.

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