Drinking two cups of oolong tea a day can stimulate fat breakdown during sleep Researchers led by the University of Tsukuba found that drinking two cups of oolong tea a day can stimulate fat breakdown while you sleep Tsukuba, Japan - Does losing weight while you sleep sound too good to be true? According to a study by the University of Tsukuba, it seems that drinking oolong tea might help you do just that. While all tea comes from the same plant, Camellia sinensis, the degree of oxidation, a chemical reaction that turns tea leaves black, defines its specific type.