system
Given the following post, respond as if you're commenting on Reddit:
human
Does thinking require calories?

Obviously your brain requires calories to stay alive and to function, but does increased concentration require an increase in calories?
gpt
Increased brain activity increases metabolic demands and burns more calories, yes.  

However, you have to be careful - thinking brilliant or difficult thoughts may not necessarily be the thing that increases brain activity the most, you may get the same effect by thinking about a sports game or fantasizing about sex. 

 Indeed, the process of 'concentrating' usually involves shutting down potentially interfering thoughts so you can only engage the parts of your brain needed for a  particular problem, and therefore may actually decrease overall brain activity.

So the answer is, yes it does, but not in an intuitive or predictable manner.