It depends on how depleted the body becomes and especially after all fat stores are gone. The body then feasts on muscle. Almost any weight loss below 10% is a candidate for muscle catabolism. As that is happening or even before, the fat layers within muscles goes away. This is what gives some bulk to muscle.

Our body has many layers of muscle and they must glide. During treatment a combination of inactivity and the body fighting the toxicity of treatment creates calcium deposts between the muscle layers and once they don't glide well, a couple of things happens. We experience pain but the body gets erratic in managing blood flow as well. This is from two perspectives.

First, the autonomic nervous system takes a hit from radiation in most of us. Second, oxidative stress is increased because of the trauma and the resulting nitric oxide cycle that constantly attacks the interior of the blood vessels. The combination of these two events reduces the efficiency of the body's ability to dilate and restrict blood vessels that then causes more buildup of calcium.

The neurological aspect of this is either caused by cellular level scar tissue in the nerve myelin or it is caused by damage to the anterior horn of the cervical spine, where lower motor neurons are stored, or the cranial nuclei of the brainstem. We are born with millions or as high as a billion lower motor neurons. Some muscles have single motor neurons, others have multiple. Lower motor neurons innervate muscle fibers for voluntary muscle movement, in simple terms.

Another important use of lower motor neurons are maintaining muscle tone through an autosynaptic process. A signal is sent to the muscle and returned to the brain to excite the muscle so we don't fall into a ball of mush. Whether it is a delay, inefficiency of the closed loop system of afferent/efferent nerve ending fibers in the neck or caused by muslces dimishing and a resultant vasoconstriction because smaller muscles need less blood, the end result is the same. Muscle fiber will not regain the same bulk and it will be more difficult to maintain the bulk. We get used to an old workout routine and don't get the same result.

Some folks like to take creatine before workouts and what that does is cause water buildup that can tax the battered lymphatic system and kidneys. If you want to hit the weights, remember all the things you used to do to lose weight and do the opposite. For example, don't walk for the first hour after eating, don't do aerobics or cardio at the end of a workout, use cardio to counter fats and avoid a low-fat fiet because the nerves need the fat.

It's all quite simple, as you can see. It only took a few hundred hours to understand how it all ties together.