Scientific explanation required please.

roguex_1979
roguex_1979 Posts: 247 Member
in Fitness and Exercise
What is the process whereby muscle becomes fat?

I saw something on telly that basically said that if you don't keep up exercise and eating lean proteins, existing muscle mass can turn into fat.

I am not suggesting this is not the case, and it would certainly explain how bodybuilders can become so fat if they don't keep up their exercise regime. but what happens to the muscle itself? I thought fat was different from muscle mass.

Replies

  • nml2011
    nml2011 Posts: 156 Member
    Muscle does not turn into fat!

    Your example of body builders getting fat is that they stop lifting but don't reduce their calorie intake and so fat forms over their muscles.
  • RobynC79
    RobynC79 Posts: 331 Member
    Muscle and fat are two different cell types - one cannot turn into the other. The colloquial references to turning either fat to muscle or muscle to fat are definitely misleading - 'replacing volume' is more like what really happens.

    When you work out heavily, muscles (which are really composed of many cell types in addition to actual muscle cells - connective tissue, interstitial fluids, blood vessels, etc.) can get larger through either addition of new muscle fibres, or by enlargement of tissue volume without adding new cells.

    Fat deposits (also containing many things other than fat cells, of course), can get smaller or larger by emptying or filling of each individual fat cell with fat. When you 'lose fat', you empty those cells, but they don't die or go away, and they don't turn into anything else. (incidentally, that's why your fat spots will always be in the same place when/if you gain weight again - the fat cells are just sitting there, waiting to fill back up).

    When people cease exercising or eat excess calories, their fat volume will increase, and in the absence of continued strain and load on the muscles, they will decrease in size. So in the same space of your body, you will now have area that was previously occupied by muscle now being occupied by fat, but the cells themselves are not changed from one to other.

    Hope that helps..
  • IronSmasher
    IronSmasher Posts: 3,908 Member
    Like Robyn and the others say, one does not turn into another.



    Following your own observations of body builders:

    The term comes from where people stop training, the muscles they've forced their body to build are no longer required, and they are allowed to waste away.

    After a lifetime of eating over 3000kcal+, the majority of athletes or body builders have a hard time making the adjustment to their intake when they cease training. Especially if training is forced to a sudden stop through injury. The excess calories consumed that are not required now training has ceased, lead instead to an increase in body fat.

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