Every substance you take into your body has a very specific effect. Any beverage containing caffeine is a stimulant and will increase energy and motion as well as stress and anxiety in the body and the mind. For some people this can be a good thing but most people that have symptoms of adrenal fatigue already have bodies that are very highly stressed, drinking caffeine makes them feel better initially but just makes matters worse. This is just one example of how if we don't understand the effect of a substance on our body, how we can make bad decisions about what to put inside of us. It takes a lot of experimentation and research until you understand what is the best approach for you personally.