I'm losing LBM?!

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chantelp89
chantelp89 Posts: 590 Member
in Fitness and Exercise
Since I've been working out I've gone down on just about everything. This includes inches, lbs, BFW, BF%, AND LBM! What's up with that? If I'm losing fat, shouldn't my LBM be going up?

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  • erinsueburns
    erinsueburns Posts: 865 Member
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    Nope, on a deficit you will usually lose both fat and lean body mass because your body has to take the deficit out of somewhere. You can manipulate that percentage by weight training, but on a deficit you are still likely to lose some LBM, you just may lose a smaller percentage of LBM.
  • chantelp89
    chantelp89 Posts: 590 Member
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    Just this month, my LBM has gone from 100.8 to 97.6. I've lost 11 inches and 5lbs
  • kodom_123
    kodom_123 Posts: 117 Member
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    If you eat at a too big calorie deficit this will happen faster than if you eat at a small cut and weight lift..those two things will help combat the LBM loss but not stop it completely.
    That's why body builders will eat at a surplus during "bulk" cycles to build new muscle. It's very hard to build new LBM when you are cutting :)
    It's just how the body works...once you know how bodies deal with "dieting" it makes it easier to do your body right.
  • erinsueburns
    erinsueburns Posts: 865 Member
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    Just this month, my LBM has gone from 100.8 to 97.6. I've lost 11 inches and 5lbs

    For one thing, how are you measuring this stuff? Accuracy varies greatly. Also, how large is your deficit and are you eating back your exercise calories?
  • bcattoes
    bcattoes Posts: 17,299 Member
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    Just this month, my LBM has gone from 100.8 to 97.6. I've lost 11 inches and 5lbs

    But if your measurements are accurate and your BF% is also dropping then you are losing more fat than LBM. And that's a good thing.
  • heybales
    heybales Posts: 18,842 Member
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    3 things can stop muscle mass loss in face of a deficit.

    Reasonable deficit, eating enough protein, resistance training.

    Studies have shown each of those, on their own, can prevent loss of LBM, and that hopefully means muscle mass though they don't always measure that separately.

    But you can still lose LBM, which muscle is merely a part of.

    If you have less mass, you need less fluids - that's LBM.
    If you have less fat, that is a little less water, that's LBM.
    If you burned a little muscle mass off, you lost glucose storage which is always with water - that's LBM.
    Of course the muscle mass off - that's LBM too.

    But likely your 5% accuracy on that has ranges overlapping so until you have farther to go.

    Some things will encourage muscle mass loss too.
    Frequent intense cardio, especially for 60 or longer.
    Not eating enough protein for level of activity.
    Not eating enough carbs for level of activity.
    Not eating enough in general for level of activity.

    Sadly, lost LBM, not even muscle mass, is lowered metabolism. Some will happen as outlined above, it's the loss of muscle mass that is bad. Hard to build back as easy as it is to lose.
  • chantelp89
    chantelp89 Posts: 590 Member
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    Just this month, my LBM has gone from 100.8 to 97.6. I've lost 11 inches and 5lbs

    For one thing, how are you measuring this stuff? Accuracy varies greatly. Also, how large is your deficit and are you eating back your exercise calories?

    The formula I found from a post on here somewhere. Can't remember the site though. I generally stay around 1200 net calories.
  • cwolfman13
    cwolfman13 Posts: 41,871 Member
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    That is the dirty little secret of dieting, you lose lean body mass in the process, it's not all fat. You can't build LBM while in a deficit of calories, but you can maintain what you have with a good strength training program and adequate protein. You have to incorporate strength/resistance training though...cardio isn't going to cut it and in fact, too much cardio makes you catabolic anyway (i.e. burns your muscles).

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