Green tea consumption is reportedly associated with various health-promoting properties. For example, it has been shown to promote fat oxidation in humans at rest and to prevent obesity and improve insulin sensitivity in mice.

In a study performed at Birmingham (UK) University, it was shown that average fat oxidation rates were 17% higher after ingestion of Green Tea Extract than after ingestion of a placebo. Similarly the contribution of fat oxidation to total energy expenditure was also significantly higher by a similar percentage following ingestion of Green Tea Extract. This implies that ingestion of Green Tea Extract can not only increase fat oxidation during moderately intensive exercise but also improve insulin sensitivity and glucose tolerance in healthy young men.

Generally, 2.5 grams of tea per 170 ml of water, or about one teaspoon of green tea per cup, should be used. With very high quality teas like gyokuro, more than this amount of leaf is used, and the leaf is steeped multiple times for short durations.

Green tea brewing time and temperature varies with individual teas. The hottest brewing temperatures are 80°C to 90°C water and the longest steeping times 2 to 3 minutes. The coolest brewing temperatures are 60°C to 70°C and the shortest times about 30 seconds. In general, lower quality green teas are steeped hotter and longer, while higher quality teas are steeped cooler and shorter. Steeping green tea too hot or too long will result in a bitter, astringent brew from low quality leaves. High quality green teas can be and usually are steeped multiple times; 2 or 3 steepings is typical. The brewing technique also plays a very important role in preventing the tea developing an overcooked taste. Preferably, the vessel in which the tea is steeped should also be warmed beforehand so that the tea does not immediately cool down.