Listening to your body

is bullshit.
Unless you are constantly crushing boundaries and breaking through plateaus in every single workout you don't have enough experience to say your body knows best.

Waking up sore and creaky is not a reason to stay out of the gym, to the contrary it's a very good reason to get in more often and lift heavy.  (Or get more sleep - but thats another post)
Not eating meat or protein every time you fuel yourself isn't keeping you in shape or the scale in an acceptable range - it's destroying your chances of a PR on lifting anything heavy or completing anything fast (READ - Doing real work).  And it's not letting you retain the strength you could have from a serious strength train.

Your body is conditioned to want the things you have always given it.  Bread, Red bull, cotton candy, cheesecake, mountain dew, doughnuts, gatorade, orange mocha frappachino, skittles, coffee mate creamer....the list is endless.  Your body wants it because it is ADDICTED to it (It = Sugar).  And your brain doesn't have the capacity to be addicted to something and at the same time know that it's addicted to it.

The fact is the only REAL experts on what your body can and can not withstand are people who meet a loose set of requirements.
They, for the most part, fulfill the following:
They have competed in or have experience with and practice and train major lifts.  ie Clean and Jerk, Snatch, Deadlift, Squats.
They have competed in or have experience with and practice and train gymnastic fundamentals.  Pullups, pushups, planches, levers, muscle-ups, parallettes, handstand walking and holds.
They have competed in or have experience in track and/or field events.
They have some sort of Professional certification with regards to Health and Fitness, and continually update their knowledge base.
They have seen lots and lots of athletes perform, have critiqued them physically and mentally, and helped them progress over time through properly scaled and focused training sessions.
They don't need to look up information regarding training questions in a book or youtube video.
They are constantly getting better.

If they have that skill set, and have spent quality time watching you train daily, then they would be the ones to look to for advice on when to go harder and when to back off.  Not your brain.  NOT YOUR BRAIN.

When you look up at your coach and they scream at you to keep going, it's in your best interest.  Whatever your brain says that isn't in line with that, injury aside, is wrong.
When you hear a coach tell you to eat more.  Do it.
Most strength coaches don't waste time or energy -  and they would be doing both if what they said didn't actually matter.

Let your coach help you go further than the deep end.  Go jump in the ocean.