If I'm "losing muscle mass", are some of my muscle cells actually disappearing?

pa5tabear

I've been running a lot lately and losing weight. Mostly getting leaner, but recently I've started to worry about losing muscle mass. I used to lift weights a lot, but I haven't done that in a few months. If I keep up my current routine, will the muscle cells shrink? Will they be consumed or disappear, so that there are then fewer muscle cells?

mazinse

yes unfortunately, the converse is true with fat cells

pa5tabear

Are you saying that fat cells never go away? Are new ones formed when you get fatter?

Under what sort of conditions do muscle cells go away? And are they directly consumed by the body for energy? How would this happen?

If there are fat cells present, will the fat cells always be "utilized" for energy before the muslce cells?

bobze

That is incorrect.

Skeletal muscle exists as a syncytium. When you loose muscle mass from under-use of muscle or something like starvation, your body breaks down the myofibers (composed of protein). Muscle cells are relatively static throughout life and do little in the way of cell divisions.

Unless a very pathological process is happening your muscle cells shouldn't be dying off (necrosis).

More info if you are interested; muscle atrophy

bobze

Fat too for the most part is relatively static. In most people, the amount of fat cells you have starting adulthood is what you keep throughout most of your adult life. These fat cells grow by hypertrophy not hyperplasia under normal circumstances and for most people. There are exceptions to this in things like inherited problems leading to obesity. But for the average American, packing on the pounds means expanding the volume of the fat cells you already have.

Jim Pivonka

People who exercise a lot, while consuming little meat, and lose significant weight, are sometimes at risk of muscle loss due to deficiency in carnitine in the body. If you fit that description, seek qualified medical or nutritional advice.

pa5tabear

Is this true? I just scanned the wikipedia on carnitine and it looks like carnitine assists in metabolism of fats. Yes, if you're consuming little meat, then you won't be getting much carnitine. Does this mean muscles will be utilized for energy more than they would if carnitine were more bioavailable in the body?