Enviga, Coca Cola and Nestlé's joint venture in the nascent weight-management beverage category, is being threatened with legal action by the better-nutrition lobby group, the Center for Science in the Public Interest (CSPI), over the carbonated, green tea-based drink's weight-loss claims.

Coke and Nestlé say the claims are based on studies that found consumption of three cans of Enviga per day could raise metabolism sufficiently to lead to a net calorie deficit of 60-100 calories in thin to normal-weight people. CSPI stated the claims were "based on inconsistent, short-term and industry-funded studies." Coke and Nestlé categorised CSPI's threat as a media stunt.

CSPI also questioned the way in which energy drinks and other functional foods were regulated, calling for stricter control by the US Food and Drug Administration.

"To ensure safety and effectiveness, companies should be required to notify the FDA before adding novel ingredients to foods for purported health benefits," said CSPI senior staff attorney Ilene Ringel Heller. Gary Roethenbaugh, research director of beverage-market analysts, Zenith International, told FF&N that weight-management drinks are building momentum in the US, especially among women, with products such as Jana Skinny Water and Celsius also gaining market share.

"Weight-management beverages do appeal to a mostly female audience, but they may also be attractive to anyone who does not want to take pills to control appetite, and would rather have a dietary supplement in a ready-to-drink beverage."