Drinking about three cups or so of coffee may help rev up your metabolism to burn a few more calories, but it’s important to keep in mind that we build up a tolerance to caffeine. That means that it may help reduce fat at first, but gradually your body will become less sensitive to it, and taking larger and larger quantities can put you in danger of feeling jittery and anxious. It can raise your blood pressure, especially if it’s already high. Plus, you can experience withdrawal symptoms like headaches, irritability, and difficulty focusing if you stop using it.