Perhaps not exactly what you are looking for, but Stephen King’s short story “Survivor Type” was written after he got fascinated by this train of thought. He consulted with a doctor friend to see how much he felt a shipwrecked surgeon could use of himself to survive on until rescue.

Hesitant to write anything down, King gained the assurance for the story after speaking with his neighbor, Ralph Drews, a retired doctor who confirmed that “a guy could subsist on himself for quite a while - like everything else which is material, the human body is just stored energy.”

I remember it being pretty good, and is supposedly one of King’s favorites. That’s the first thing that popped in my head after reading your question.