% body fat, muscle mass and the rest. What's the science?

richardholt2011
richardholt2011 Posts: 118 Member
in Health and Weight Loss
So my new scales tell me that my body fat is 37% and my muscle mass is 31% which implies 31kg and 27kg respectfully. That leaves another 32% or 27kg unidentified - which I assume is my brain (not much there), skin, intestines, and all the half-digested pork pies etc etc contained in the latter.

So here is my question. If i lose (for example) 1 kg a week, and manage to avoid losing muscle through a mix of cardio and lifting weights, does that mean that I'm losing 1 kg of fat, or will some of it come out of the 'other' category? My instinct tells me that, with the possible exception of the afore-mentioned pork pies, the other category shouldnt decline - i certainly dont want my brain to shrink! it's struggling as it is.

Does anybody know? OK my interest is kind of academic - i know that the big issue is my behaviour and to stop stuffing my face - but it's something that I'm curious about.

Replies

  • mattashbrock
    mattashbrock Posts: 38
    The other is a combination of a ton of different things, organs, smooth muscle, bones etc. The device you are using most likely uses a bioimpedance method where it sends an electric pulse through your body and measures the time it takes to get back to the other electrode. Muscle/fat/bone/water all conduct electricity differently so by measuring this it can give a rough estimate of body composition. While this method can give an estimation of body composition there are many factors (mostly your current hydration state) that can affect the measurement. Trying to convert the percentage into actual pounds should not be something i would rely on. Use the body composition as a comparison tool over time to track changes and that you are moving in the correct direction. When you loose weight you typically are losing water, fat and muscle. Yes you can minimize muscle loss by strength training and by eating only a minimal deficit loss, however in most cases you will be losing both fat and SOME muscle.
  • richardholt2011
    richardholt2011 Posts: 118 Member
    Thanks mattashbrock but with respect like everybody else you have sidestepped the issue (none of the so-called academic research i have looked at answers the question either) - you say that 'in most cases you will be losing both fat and SOME muscle' but my question is will i be losing some of THE REST or not? my sense is that if it is organs and bones then they are not likely to shrink as a result if dieting. I hope not! But maybe i am wrong
  • LadyPakal
    LadyPakal Posts: 256 Member
    There will be some other losses - blood volume for example will decrease with your size, body water content will also decrease with your size (even if the overall %age increases). Content of your digestive system will also vary. Unless you suffer from osteoporosis, your bone mass should not change over time. Brain - well that depends on whether you have CJD...
  • SteveJWatson
    SteveJWatson Posts: 1,225 Member
    Your viscera are unlikely to change in either size or mass unless you have some kind of disease.
  • mattashbrock
    mattashbrock Posts: 38
    You also have visceral fat which surrounds your organs. This is especially common in men giving us a 'beer belly'. Some of the bio impedance scales/devices take this into account and some only are measuring subcutaneous fat. So sme of the "other" could be visceral fat.
  • patmoomur
    patmoomur Posts: 31 Member
    I have no idea, but I enjoyed reading your blurb. To me you would have to eat more protein while working out to avoid the muscle loss. Does that make sense? Who knows? I just glad to see the fat come off and will work more and more on the muscle and stamina when I can tolerate the exercise. Joint pain being the worst I have to deal with. But whatever, maybe your question will get an academic answer soon.
  • CoderGal
    CoderGal Posts: 6,800 Member
    better chance of fat lost - do it with resistance training

    Generally, when you lose weight, you lose muscle, fat, and water.

    Also, bia scales are not the most accurate. As for what the readings can be, many of them try to read LBM (lean body mass, as in anything but fat), fat, bone density, body water, etc.
  • BarackMeLikeAHurricane
    BarackMeLikeAHurricane Posts: 3,400 Member
    You lose some of the "other stuff" along with fat. Even if you manage to preserve every single little muscle fiber while losing weight, your body will still lose things like connective tissue. If you lose weight, there's less stress on your joints so the extra connective tissues are no longer needed and broken down.
  • DrMAvDPhD
    DrMAvDPhD Posts: 2,097 Member
    Most of the other stuff is water
  • richardholt2011
    richardholt2011 Posts: 118 Member
    Oooh some of these answers make me feel quite queasy! Not sure I should ever have started this! Bottom line seems to be that a bit of the 'other stuff' goes, but probably not a huge amount. Nothing I can do about it of course even if I wanted to, but interesting to know, yuckiness aside.
  • Vailara
    Vailara Posts: 2,468 Member
    I don't know, but it makes sense to me that a little bit of what you lose could be the other stuff. Surely a 40stone person is going to have more fluid on them than a 10stone person? And even bone can become lighter. I have no idea how much that would account for - maybe it's negligible. It's an interesting question!

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