Thermogenic drinks are marketed to consumers as a means to increase metabolic rate, or the number of calories burned. A large number of products are available with a wide variety of different formulations, but few have been clinically tested to determine efficacy. Common ingredients are caffeine and green tea extract which have been shown in prior studies to raise metabolism, but the magnitude of caloric burn associated their use remains unclear. Researchers at the University of Oklahoma put one product to the test. They had healthy subjects consume a very low calorie thermogenic product consisting of a green tea extract, caffeine and an assortment of other nutrients or a non-caffeinated placebo and measured metabolic effects for 3 hours after ingestion. The most significant finding was that thermogenic supplement raised metabolism by 106 kcal over the 3 hour period compared to placebo. This was associated with a greater increase in fatty acid in the blood providing an indication of enhanced fat breakdown in adipose tissue. The authors conclude that although this was only an acute study, the findings suggest that the thermogenic drink may be effective to promote fat loss independent of diet or exercise.

Dalbo VJ, Roberts MD, Stout JR, Kerksick CM. Acute effects of ingesting a commercial thermogenic drink on changes in energy expenditure and markers of lipolysis. J Int Soc Sports Nutr. 2008 Feb 20;5:6.