FORGET zero-calorie soft drinks. That's old school. How about a "negative-calorie" green tea?

Coca-Cola announced on Wednesday it was ready to introduce its new calorie-burning carbonated green tea, Enviga, in the US, a nation rebelling against waist-inflating sugary colas.

Coke and its tea-brewing partner, Nestle, maker of Nestea, will introduce Enviga in the New York City-New Jersey metro area and Philadelphia on November 6. It will launch nationally in February and in Latin America, Europe and Asia later next year.

Coke hopes to jump-start cold tea sales with the new drink, which promises to jump-start your metabolism, too. Coke and Nestle say three 12-ounce (340 gram) cans will burn 60-100 calories (.25 to .42 kilojoules) in healthy adults aged 18-35. Each drink contains 5 calories, hence the claim it is a negative-calorie drink.

Coke says it has the science to prove its claim.

It put test subjects in a metabolic chamber (the kind divers use to depressurise) and had them drink three Envigas and eat a set diet during a 24-hour period. The subjects burned an average of 106 calories more after drinking Enviga than after drinking plain green tea, said Dr Rhona Applebaum, Coke's chief scientist.

The study will be published before the drink is launched next month, she said.

Coke needs Enviga to work. The company trails Pepsi, Arizona and Snapple in the ready-to-drink tea market in the US. And Coke's share of the market declined during the period. That's a problem because cold tea was the fastest growing non-carbonated beverage category during the first half of 2006, according to Beverage Digest.

In recent years, beverage companies have raced to develop new drinks, such as flavoured bottled water, sports drinks and teas, to make up for declines in sales of sugary soft drinks.

While Pepsi has led Coke in several of the new categories, it has not announced any plan to offer a calorie-burning tea.

Enviga combines caffeine and the antioxidant EGCG (Epigallocatechin gallate), found naturally in green tea leaves, to speed up the metabolism. The green tea used for Enviga comes from a Nestle plantation in India that produces a leaf rich in EGCG, company officials said.

Consumers have become suspicious of weight-loss claims, and Dr Applebaum said Coke had not exaggerated its claims. "This is not a magic bullet," she said.

An assistant professor of nutrition at the University of Alabama, Marie-Pierre St-Onge, said the claims for Enviga were plausible. Studies had shown EGCG and caffeine in big doses could increase metabolism and burn more calories than water alone, she said.