The role of caffeine: 1, can stimulate the excitability of the sympathetic nerve, and the sympathetic nerve can make breathing, heartbeat to get a good increase, which can play a role in improving mental state, in relieving fatigue, refreshing the efficacy and role will be relatively obvious. So in some people feel sleepy, no spirit, appropriate to drink a little coffee can play a good role in regulating nerves and refreshment. 2, can promote the body’s metabolism, especially to make the catabolism more enhanced, in this case if appropriate to drink a little coffee, can improve the catabolism, and thus can avoid excessive energy accumulation in the body, for the prevention and control of obesity also has a certain Effectiveness and role.