This is a truth that revolutionized my life. "Humans only have the ability to make a certain number of good decisions per day." When you are tired, your cognitive brain doesn't function as well, and you start to make bad decisions. By that point you've exhausted your mental capacity for that day. That's why a lot of binge eating happens late at night, that's why when you get home after a hard day you order takeout for dinner. So the solution is, not to resign yourself and just make bad decisions, but to limit the number of decisions you have to make each day by setting systems and habits in place.
Hopefully, now that you're aware that you are literally burning up brain cells deliberating, you may spend less time and energy on things that could be put on autopilot. Try implementing routines that create habits, so you automatically make good decisions, and never run out of brain power!