What a brilliant idea: A drink that increases your metabolism while clocking in at a svelte 5 calories per can providing a "Negative calorie" effect. At last, sitting around on your ass while drinking carbonated beverages can now actually reduce the size of that very ass! Well sadly, not quite.
A quick survey of the Enviga website reveals a number of things:
1) The Enviga website is so flash that something has to be up.
2) EGCG is the active ingredient in this drink, and is an antioxidant found naturally in green tea.
3) Enviga contains more EGCG than any other premixed beverage (Which presumably means that it contains less than regular green tea).
4) Of the 5 studies cited in its "Science Section", two show no effect on metabolism following the consumption of EGCG and the only study which shows results like the ones reported on the front page of the website is both unpublished and conducted by Nestle scientists. Nestle is, entirely unsurprisingly, Coca-Cola's partner in this venture.
5) In order to achieve the advertised effect, one must consume 3 cans of Eviga per day at a cost of around $1600 per year. Actually, that isn't mentioned, but I just worked it out and I hate to waste effort.
Things are starting to look less promising for the "lose weight while merely watching people exercise on TV" idea. In fact the claims made by Coca-Cola are considered to be so flagrantly overblown by the Centre for Science in the Public Interest that it has issued the makers with a warning that it will sue if the claims are not discontinued.
In the meantime, people looking to lose a little weight would probably be better advised to head down to the local supermarket and buy some green teabags. Or, better yet, I'm sure that $1600 would some way towards a membership at the local gym.