It can fasten metabolism because it stimulates sympathetic nervous system, in order to make a comment on this topic we need to understand how it works.
Caffeine and adenosine are similar in structure; when you consume caffeine it binds directly to adenosine receptors, it is a neurotransmitter that slows down celluar movement. When adenosine is decreased dopamine and glutamate increases; as i said your body enters sympathetic fight and flight mode and your celluar movements fastens.
In order to combat increased caffeine consumption and binding to recept orsbrain creates even more adenosine receptors, which makes withdrawal like effects such as fatique, headaches, anxiety and more.
Only use it when necessary, see it as a tool which helps you with an important task when you are tired.
