It may cause an increase in blood pressure and should not be used by people who are on a number of other medications, such as antidepressants. Drinking tea (especially green tea, white tea, and pu-erh tea) has also been suggested as a weight loss aid.
Short of this sort of hard reset of the microbiome, preliminary research has shown that adding even a single bacterial species to a person’s gut can alter her metabolism. The relationship between microbes and weight gain has long been overlooked in humans, but people have known about similar effects in animals for decades. After World War II, antibiotics became affordable and abundant for the first time.