Why coffee on an empty stomach?

Coffee is our commonly used beverage, coffee contains caffeine, can excite the brain nerve, enhance the metabolic rate of the body, so that the metabolic rate of the body enhanced. It contains a small amount of fat, vitamins, can speed up the heart rate, blood pressure, promote blood circulation, enhance myocardial contractility, and increase intestinal motility. Weight loss process should be controlled mouth, open legs, eat less high protein, high calories, high fat food, increase a certain amount of exercise. Persist to make the body muscle tissue gradually increased, really improve the basic metabolic rate, to achieve the effect of weight loss.