Eating at a severe deficit- lose fat or muscle?

abbylg1983
abbylg1983 Posts: 177 Member
in Health and Weight Loss
OK, I am not doing this, this question is for informational purposes only. Let's say I decided to eat at a serious deficit- like 800 calories per day while working out. Some would say while I'd burn fat, I'd also burn lean muscle mass which is bad. Some say I would burn through all my fat (like down to <10%) before burning off muscle.

I did read an experiment involving military where the men (all average sized, with body fat percentages in the low teens) supposedly went down to 5% before losing any muscle, but could find no quantitative data supporting that- the study just said that's what happened. I just can't imagine that would be true.

If losing your fat is as easy as starving yourself for a short period of time, wouldn't we all be skinny? I thought part of the problem with starving yourself (and don't get me wrong- I mean this from purely a fat loss point of view, not from a general health and wellness point) was you would lose muscle along with fat.

Replies

  • mmapags
    mmapags Posts: 8,934 Member
    You would burn and lose both fat and muscle in that large a deficit. Probably in roughly equal amounts. Those who have suggested that you would lose fat until nearly depleted then muscle do not understand the physiology of it. There is another thead here posted yesterday by a freind of mine who lost about 50 pounds WHILE STRENGTH TRAINING and he lost fat to muscle in a little more than a 2/1 ratio. You body in extreme deficit does not prioritize fat over muscle. It takes what it needs and if it can't get enought amino acids from you the protein in your diet, it takes it from your muscle tissue.
  • Sidesteal
    Sidesteal Posts: 5,510 Member
    OK, I am not doing this, this question is for informational purposes only. Let's say I decided to eat at a serious deficit- like 800 calories per day while working out. Some would say while I'd burn fat, I'd also burn lean muscle mass which is bad. Some say I would burn through all my fat (like down to <10%) before burning off muscle.

    I did read an experiment involving military where the men (all average sized, with body fat percentages in the low teens) supposedly went down to 5% before losing any muscle, but could find no quantitative data supporting that- the study just said that's what happened. I just can't imagine that would be true.

    It's possible that you, or someone else, is misunderstanding the data. I would be absolutely baffled if the result was "no loss in lean mass". Consider that, even if someone goes from 20% bodyfat to 5% bodyfat, they could lose a ton of lean mass in this process because each measurement is taking a snapshot of fat vs lean mass. If they both decrease, but fat decreases at a much greater rate, you could reduce bodyfat % even though you are losing lean mass.


    In regards to your original question, I believe there is data supporting the notion that as your deficit increases, the likelihood of lean mass losses are increased and consequently your protein requirements may also increase.

    I would speculate that, in general, smaller deficits retain LBM more successfully, all other variables equal. Obese people and people new to training who are recently introducing resistance training will retain it at a much better rate.
  • abbylg1983
    abbylg1983 Posts: 177 Member
    OK, I am not doing this, this question is for informational purposes only. Let's say I decided to eat at a serious deficit- like 800 calories per day while working out. Some would say while I'd burn fat, I'd also burn lean muscle mass which is bad. Some say I would burn through all my fat (like down to <10%) before burning off muscle.

    I did read an experiment involving military where the men (all average sized, with body fat percentages in the low teens) supposedly went down to 5% before losing any muscle, but could find no quantitative data supporting that- the study just said that's what happened. I just can't imagine that would be true.

    It's possible that you, or someone else, is misunderstanding the data. I would be absolutely baffled if the result was "no loss in lean mass". Consider that, even if someone goes from 20% bodyfat to 5% bodyfat, they could lose a ton of lean mass in this process because each measurement is taking a snapshot of fat vs lean mass. If they both decrease, but fat decreases at a much greater rate, you could reduce bodyfat % even though you are losing lean mass.


    In regards to your original question, I believe there is data supporting the notion that as your deficit increases, the likelihood of lean mass losses are increased and consequently your protein requirements may also increase.

    Hard to say, because the study I read offered no data or information on how they measured body fat and muscle loss. There was just a conclusion stating the soldiers only started to lose lean muscle after 8 weeks, or as the body neared essential fat.

    If you know where I could find the other data about lean muscle loss I'd love to read it.
  • mmapags
    mmapags Posts: 8,934 Member
    Try searching terms like "maintainig lean mass in deficit" at www.bodycomposition.com.
  • Sarauk2sf
    Sarauk2sf Posts: 28,072 Member
    The 'study' you are referring to is actually a podcast and does not cite sources. The only related actual study that I have been able to find it this one (it has one of the same authors noted in the blog/podcast):

    http://www.ajcn.org/content/83/5/1068.full

    What the study actually shows is that you will lose only muscle mass at a really low body fat %. It does not actually show that you will lose no muscle mass above that. That being said, the sample size of this study was very small and there were some other issues with the testing procedures. Also, I cannot find where the 5% is mentioned in this study.

    I have asked a few times on threads for people to provide the actual study that is referred to in the podcast/blog (as there are some differences to the study so the above may not be the correct one) but no luck so far. If anyone does know where to find it, it would be great to have a look as this keeps getting quoted as the source for not worrying about muscle loss.


    ETA: to clarify a little so it is not confuse anything shown the study provided by Acg's below - the study above was conducted with no resistance training, lots of exercise and low protein levels (i.e. situations conducive to losing LBM).
  • Acg67
    Acg67 Posts: 12,142 Member
    Effects of Resistance vs. Aerobic Training Combined With an 800 Calorie Liquid Diet on Lean Body Mass and Resting Metabolic Rate

    http://www.jacn.org/content/18/2/115.full
  • toriaenator
    toriaenator Posts: 423 Member
    unfortunately i did that haha. ate 800 or less and burned off about 700 a day. let me tell you that the muscle rapidly went away. first you shrink into a smaller version of your still fat self (skinny fat) then fat comes off but its stubborn.

    BAD IDEA GUYS. took me months and months of strength training and upped cals to regain my muscle.
  • ArroganceInStep
    ArroganceInStep Posts: 6,239 Member
    Effects of Resistance vs. Aerobic Training Combined With an 800 Calorie Liquid Diet on Lean Body Mass and Resting Metabolic Rate

    http://www.jacn.org/content/18/2/115.full

    Doesn't that imply that a VLCD with sufficient resistance training will avoid all LBW loss? Maybe I'm misreading, and I don't think it's a good idea, but:
    No decrease in LBW was observed in R+D.
  • Acg67
    Acg67 Posts: 12,142 Member
    Effects of Resistance vs. Aerobic Training Combined With an 800 Calorie Liquid Diet on Lean Body Mass and Resting Metabolic Rate

    http://www.jacn.org/content/18/2/115.full

    Doesn't that imply that a VLCD with sufficient resistance training will avoid all LBW loss? Maybe I'm misreading, and I don't think it's a good idea, but:
    No decrease in LBW was observed in R+D.

    Small sample size and subjects were both overweight and sedentary which could have skewed results. Also the accuracy of hydrostatic weighing varies, so that has to be taken into consideration as well
  • xarge
    xarge Posts: 484 Member
    Doesn't that imply that a VLCD with sufficient resistance training will avoid all LBW loss? Maybe I'm misreading, and I don't think it's a good idea, but:
    No decrease in LBW was observed in R+D.

    On baseline BF% 46.2 ±6.8.
  • abbylg1983
    abbylg1983 Posts: 177 Member
    Effects of Resistance vs. Aerobic Training Combined With an 800 Calorie Liquid Diet on Lean Body Mass and Resting Metabolic Rate

    http://www.jacn.org/content/18/2/115.full

    Doesn't that imply that a VLCD with sufficient resistance training will avoid all LBW loss? Maybe I'm misreading, and I don't think it's a good idea, but:
    No decrease in LBW was observed in R+D.

    That's what I got out of the study. That you would lose more weight just doing the anaeorbic workouts but some of that would be lean muscle mass (although what percentage of fat to muscle I don't know) but resistance training while severely cutting calories would prevent lean muscle mass loss. I am no expert but I would think even with resistance training your lean mass would suffer on that high of a deficit.
  • Sarauk2sf
    Sarauk2sf Posts: 28,072 Member
    Effects of Resistance vs. Aerobic Training Combined With an 800 Calorie Liquid Diet on Lean Body Mass and Resting Metabolic Rate

    http://www.jacn.org/content/18/2/115.full

    Doesn't that imply that a VLCD with sufficient resistance training will avoid all LBW loss? Maybe I'm misreading, and I don't think it's a good idea, but:
    No decrease in LBW was observed in R+D.

    That's what I got out of the study. That you would lose more weight just doing the anaeorbic workouts but some of that would be lean muscle mass (although what percentage of fat to muscle I don't know) but resistance training while severely cutting calories would prevent lean muscle mass loss. I am no expert but I would think even with resistance training your lean mass would suffer on that high of a deficit.

    The individuals in the study had a high bofy fat %. I do not think that it changes the fact that the study shows definate benefits to maintaining LBM by resistance training - but the loss of no LBM at all is really only indicated for the sample population:

    If you look at the stats of the test subjects, the average BF% was 44.5% (no resistance training) and 46.2% (resistance training) with a SD of 7 for both.
  • xarge
    xarge Posts: 484 Member
    The individuals in the study had a high bofy fat %. I do not think that it changes the fact that the study shows definate benefits to maintaining LBM by resistance training - but the loss of no LBM at all is really only indicated for the sample population:

    If you look at the stats of the test subjects, the average BF% was 44.5% (no resistance training) and 46.2% (resistance training) with a SD of 7 for both.


    ^To add to this, on table 2 of that study, you can see that there is still LBM loss in R+D but significantly lower compared to C+D. On the other hand despite the higher LBM loss, BF% loss is greater in C+D.
  • ArroganceInStep
    ArroganceInStep Posts: 6,239 Member
    Ahh, thanks for the clarification. I managed to miss that. Makes sense then.

Categories