Drinking coffee may have a small effect on weight loss due to its potential to increase metabolism and reduce appetite, but it is unlikely to have a significant impact on weight loss on its own. However, abruptly stopping or significantly reducing caffeine intake can cause withdrawal symptoms such as headaches, fatigue, and irritability. These symptoms typically last for a few days to a week and gradually improve as the body adjusts to the change. So, if someone is trying to stop drinking coffee, they may experience headaches as a withdrawal symptom, but it is not directly related to weight loss.