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Study Casts Doubt on Enviga Calorie-Burning Claims

Many People May Expend Less Energy, Not More

February 12, 2007

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Coca-Cola and Nestle have claimed that an unpublished Swiss study shows that their new green-tea-flavored soda Enviga burns more calories than it provides, resulting in what sounds like a dieter's Holy Grail: "negative calories."

Given the size of the study (just 31 young, lean subjects), its duration (only 72 hours), and the funding of the study (Nestle itself!), the Center for Science in the Public Interest (CSPI) was skeptical enough to file suit in federal court against the companies earlier this month.

But the full study, published today in the journal Obesity, shows that there's even less foundation for the weight-loss properties than Enviga's makers imply in their marketing materials.

In the study, 31 young men and women ate strict calorie-controlled diets and drank the equivalent of three cans of Enviga each day for three days. Participants spent the third day in a special chamber that measured how many calories they burned.

Most expended slightly more calories after drinking Enviga, but Coca-Cola and Nestle didn’t disclose publicly that the drink's ingredients had the opposite effect in a significant number of the study participants.

Six of the 31 participants actually burned up to 10 percent fewer calories after three days of consuming the ingredients in Enviga.

"If you follow Coke's and Nestle's logic, then about one in five consumers will eventually get fatter from drinking Enviga every day," said CSPI senior nutritionist David Schardt. "They've been withholding this information from their customers."

The long-term impact of Enviga isn't clear, either. Outside the carefully controlled environment of the laboratory, some people might eat more food or engage in less physical activity and thus negate the benefit of any extra calories expended, according to Schardt.

The scientists who conducted Coca-Cola's and Nestle's research seem to agree that the companies' claims are premature. In the study published today they concluded that "more long-term studies would be necessary" to confirm the benefit of a drink like Enviga for weight control. Coke and Nestle evidently couldn't wait for that, according to CSPI.

Coca-Cola spokespeople have maintained that Enviga isn't marketed as a weight-loss product, while simultaneously claiming that Enviga is "much smarter than fads, quick-fixes, and crash diets," and that it keeps "those extra calories from building up." One Coke official seemed to suggest that Enviga can actually replace some physical activity.

"I can choose to walk up the stairs or I can choose to have a can of Enviga," Helen Falco, Coke's director of nutrition and health policy, told USA Today.

No Foundation

The editors of Obesity today issued a press release that pointedly states that the Enviga study should not serve as a foundation for weight-control claims.

"Increasing metabolism is not the same as causing weight loss or prevention of weight gain," said Eric Ravussin, professor at the Pennington Biomedical Research Center and president of the Obesity Society. "Increases in metabolic rate may be easily offset by increased energy consumption or decreases in energy expenditure. Far more extensive studies are needed before any claim for efficacy in human weight management can or should be made on the basis of this study."

Enviga consists of carbonated water, calcium, concentrated green tea extract, unspecified "natural flavors," caffeine, phosphoric acid, and the artificial sweeteners aspartame and acesulfame potassium. The company says its green tea extracts are high in an antioxidant called epigallocatechin gallate, or EGCG.

In addition to being the target of a CSPI lawsuit, Enviga is the subject of an investigation launched by the office of Connecticut Attorney General Richard Blumenthal. He has demanded any studies that the companies have that relate to its weight-loss claims, which he said might just be "voodoo nutrition."

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