Because when I'm tired, I just can't get hungry...
People use the same excuse for not exercising. Its a handy plausible excuse, but the truth is that they just don't want to exercise.
If you can think of a hundred reasons "why you aren't in the mood to do something" then I can assure you of one thing, you have no real desire to do that thing.
You have never been to tired to eat?
I guess you have never been truly tired.
I am often too tired to eat, and I love food.
Some years ago they took a poll about the priorities between men and women. For men, sex was the number one priority in life. For women, sex was down the list behind cleaning the refrigerator. I’m only slightly exaggerating. Sex was about no. 37 on the priority list for women.