When the body is ill, it can heal itself or it can fail.
Mostly, the body fails, and much of this failure, in the first half of life, is due mostly to poor stewardship by the owner and by doctors. Late in life, the odds are firmly against healing, regardless of good stewardship, if that is even possible with all of the idiotic medical advice we are given (and are gullible enough to believe).
Doctors can help or hurt healing – mostly, doctors hurt the process of healing by weakening the body, often interfering with nature, with processes that have been selected for by the relentless pressures of a merciless nature.
Evolution does not hit the bull’s eye, but it does not miss the target. The facts of physiology must always be front and center in any biological model development.
Doctors are wrong to treat the body as a right idiot, opposing what the body is trying to do to help us to survive. Even when the body throws the cachectic response, it is a Hail Mary; the alternative is quick death – give the body enough of everything that it is looking for (hint: 30 or so grams of glutamine a day helps, and even more vitamin C; make a list of what the body is looking for, including non-essential nutrients that it is not making enough of- and give it enough of those things, by infusion if necessary) and the problem of slow death by cachexia may go away.
In healing the body, surgeons mostly help, while other doctors mostly hurt.