This is actually one of the reasons I do what is now called "Intermittent Fasting". I found in my teens that I was much, much more focused and alert on an empt

This is actually one of the reasons I do what is now called "Intermittent Fasting". I found in my teens that I was much, much more focused and alert on an empty stomach. I've always assumed it had to do my insulin response to meals as low-carb diets had a similar effect but not eating during the day was just easier.