Compared to the placebo and caffeine, green tea extract consumption produced a significant 4% increase in 24-hour energy expenditure. If you consume 2,000 calories per day and don't gain or lose weight (you're in energy balance), an increase of 4% would translate roughly into an 80-calorie daily difference. Over a year, this could result in 89 pounds of weight loss.
Though I'd much rather sit back and sip tea that even think about math, lol, there seems to be an error here.
First of all, you must burn 3500 calories more than you consume to lose one pound of fat. 80 calories per day x 365 days per year = 29,200 calories. This does not equal 89 pounds of weight loss. It would actually be 8.34 pounds per year.
Another way to look at it is 80 calories per day x 30 days per month = 2400 calories, which is less than one pound burned.
It would be nice to be able to burn 89 pounds a year just by drinking green tea, but it's just not possible
Also, the study was based on significant amounts of green tea extract. The product was taken 3 times daily (with each meal), with each dosage containing 50mg caffeine and 90mg EECG, for a daily total of 150mg caffeine and 270mg EECG.
It might be more difficult to get that dosage from green tea alone. According to http://www.adagio.com/info/caffeine.html green tea only has 20mg caffeine per cup. According to the University of Maryland Medical Center, http://www.umm.edu/altmed/ConsHerbs/GreenTeach.html it would take 3 cups of green tea to get 240 to 300 mg of EECG. Maybe add a cup of coffee or a diet cola in there somewhere, lol.
If I'm wrong, please let me know. Math isn't exactly my sport of choice