New evidence is emerging that green tea can even help dieters. In November, 1999, an American nutrition magazine published the results of a study at the University of Geneva in Switzerland. Researchers found that men who were given a combination of caffeine and green tea extract resulted in significant increase in energy expenditure (a measure of metabolism), burning more calories than those given only caffeine or a placebo.
Japanese researches also examined the effect of green tea on metabolism. They concluded that green tea increased metabolism by 4% for 120 minutes. There is also research indicating that drinking green tea lowers total cholesterol levels, as well as improving the ratio of good (HDL) cholesterol to bad (LDL) cholesterol.
The researchers indicated that their findings have substantial implications for weight control. A 4% overall increase in 24-hour energy expenditure was attributed to the green tea extract, however, the research found that the extra expenditure took place during the daytime. This led them to conclude that, since thermogenesis (the body's own rate of burning calories) contributes 8-10% of daily energy expenditure in a typical cubject, that this 4% overall increase in energy expenditure due to the green tea actually translated to a 35-43% increase in daytime thermogenesis.