This effect on prana(Life-force) is easily understood by most of us in the western world.

Broadly speaking surical issues are legion, involve hundreds of thousands of cases & fall into 3 areas:

1. Pre-Surgical
2. Surgical
3. Post-Surgical

Presurgical issues revolve around:
Wrong identity, wrong/inappropriate/wrong-dosage medication, Xray-Radiation side effects, physical therapy side-effects, side-effects of pre-surgical medications, etc

Surgical errors revolve around:
Puncture/Laceration/Transfusion errors, surgical medications/anaesthesia side-effects, Clots & embolism formations, Surgical Shock, blood loss shock, etc

Post surgical issues revolve around:
Post surgical infections, Catheterisation infections, Wrong Medications, medication side-effects, Foreign body's left internally from operating theatre, Clot formations, post surgical shock, blood loss shock, delayed wound healing, etc

Of course from many of these issues the body will recover however things like shock, infections & radiation issues can seriously weaken the life-force(Prana) of the cells. Indeed these may even kill, suceeding in taking the very life force itself away from your cells.
And so it is these latter 3 issues which can leave longterm deficits in the level of Prana in the cells therefore inhibiting the life force, therefore adding to the incapacity for a strong Prana to keep a healthy muscle-to-fat ratio AFTER surgical procedures.

More soon.