As a person who did 21km run in fasted state (didn't eat for 36 hours before) and then swam in a 7 degrees pond with ice, I can definitely say: NO.

I tried for 8 hours straight to code just a little bit, but was unable to. I guess that is burnout, or, in general, understanding that I am not interested in all this computer stuff anymore after doing it for 15 years.