Why not eat below BMR?

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Ploogy
Ploogy Posts: 115 Member
in Health and Weight Loss
I've wandered through these forums and I see the idea of not eating below one's BMR touted as gospel. The usual line is that BMR is the minimum caloric needs of a body in order to function (the "if you were in a coma" line is often used). However, there is never any accompanying explanation as to why this number has any correlation to one's entrance into the dreaded starvation mode. The very reason we carry fat on our bodies is as fuel reserves for when we are not providing our body with adequate energy. If so, can someone point me to any scientific evidence that someone's body, if eating below BMR, will decide to catabolize its own organs instead of using fat reserves? It's actually quite counterintuitive in my eyes, and I'd love to learn what is behind this mechanism, if it exists.

As a corollary, for those who believe in the BMR as a baseline, there seems to be a conflict between those who believe that you simply need to eat enough calories to meet your BMR (regardless of any activity expenditure) versus those who say that one needs to at the least NET calories equivalent to BMR. Why does this conflict exist, if in fact, it is apparently unclear that BMR should even be seen as some sort of threshold?

Thanks in advance for the help on this! I could use it!
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Replies

  • CristinaL1983
    CristinaL1983 Posts: 1,119 Member
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    Bump because I'm waiting with bated breath to see the responses.
  • naseak
    naseak Posts: 98 Member
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    bump
  • missmegan831
    missmegan831 Posts: 824 Member
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    bump
  • akp4Him
    akp4Him Posts: 227
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    bump
  • Mads1997
    Mads1997 Posts: 1,494 Member
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    Most dieticians will have you eating under your BMR if you have a lot of fat to lose.
  • Doberdawn
    Doberdawn Posts: 732 Member
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    I don't think it is that your body begins to "cannibalize" the organs. The problem is that there is a certain amount of fuel that your body needs just to function. When you don't supply it, but you still expect it to do its job, you put a strain on those organs and jeopardize your health and doing damage to the body. It takes energy even just to burn the fat you want to use, just like it takes energy to digest and use the food you eat. Conversion, consumption, digestion, and waste systems all require energy. Expecting to get energy from them while not providing energy to run them is like expecting a combine harvester to plow fields so you can eat without putting any gas in the tank. I'll see if I can find any links that are more authoritative and scientific than this... but that's my basic understanding.
  • twinketta
    twinketta Posts: 2,130 Member
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    I do not think it is about organs but more about muscle?

    But having said that not feeding your body as a whole organism will eventually deplete and drain ie skin, hair, nails will not do well if you do not feed your body in a good way.

    You will find lots of scientific evidence that anorexics can deplete their organs by eating below the BMR consistently.

    This is the short answer, you sound educated, so you would not need me to tell you any of this?
  • Doberdawn
    Doberdawn Posts: 732 Member
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    Twinketta is right about losing your Lean Body Mass too. You will lose muscle, a lot more than you want to. That is another problem with radical cutting diets.
  • Ploogy
    Ploogy Posts: 115 Member
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    This is the short answer, you sound educated, so you would not need me to tell you any of this?

    No, it has nothing to do with education! If I was actually educated in this arena, I wouldn't be asking the questions, so rest assured that I am most definitely not. My reasons for asking is that I am trying to take a good, hard look at the principles espoused in this Community, and I feel that some of the fundamental precepts, like this, are just stated as accepted fact with no inquiry into where this comes from.
    I don't think it is that your body begins to "cannibalize" the organs. The problem is that there is a certain amount of fuel that your body needs just to function. When you don't supply it, but you still expect it to do its job, you put a strain on those organs and jeopardize your health and doing damage to the body. It takes energy even just to burn the fat you want to use, just like it takes energy to digest and use the food you eat. Conversion, consumption, digestion, and waste systems all require energy. Expecting to get energy from them while not providing energy to run them is like expecting a combine harvester to plow fields so you can eat without putting any gas in the tank. I'll see if I can find any links that are more authoritative and scientific than this... but that's my basic understanding.

    Cannibalize may be the wrong words, but the point is that BMR is spoken of as a threshold under which the body is detrimented, and starvation mode begins (some implying it is just around the corner, even). You are right that the body needs a minimum amount of energy, it must. However, even taking into account both the energy to mobilize fat and the rate at which the body is able to do this - which is what you I think are getting it - there isn't, on the face of it to me, any basis to see BMR as anything other than a useful number from which to calculate one's total daily energy expenditure. I don't see how from where a conclusion is drawn that it serves as some sort of threshold above which the body will grab from organs or feel the need to downregulate and enter "starvation" mode.
  • Ploogy
    Ploogy Posts: 115 Member
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    Absolutely, not questioning that. If someone's BMR was 2000 and they were 350lbs overweight, and instead of eating 4500 calories a day, they suddenly dropped to 2100, that would be, by all accounts, a drastic diet. But it's still above BMR! So technically no problems should exist. Just pointing out how I don't understand the magic of the BMR figure as a threshold for starvation and metabolic downregulation.
    Twinketta is right about losing your Lean Body Mass too. You will lose muscle, a lot more than you want to. That is another problem with radical cutting diets.
  • gpizzy
    gpizzy Posts: 171
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    My understanding is that your body goes for muscle before fat, and will eventually get used to operating at a reduced efficiency because there isn't enough new food energy. I dont have any links for you, just what I've read over the years from here, books, and websites.

    I think it's a choice, do you want to lose fat or muscle? I personally want to lose fat, so I dont want to eat less than 1200 calories or go into starvation mode.

    If you look at people anorexic who eat very little or nothing, they lose weight... lots, they lose all their muscle first and then can be 'skinny fat'. eek!
  • Doberdawn
    Doberdawn Posts: 732 Member
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    There are some articles on Bodyrecomposition.com - excellent and informative site - that talk about these things. Apparently there was a study where folks ate below BMR to lose weight. But, then it damaged their BMR and their body reduced its functioning to correspond to the starvation conditions. When they wanted to return to normal eating for their sizes and to restore their BMRs to normal, there was no permanent damage to their metabolisms, but they had to regain all the fat they lost. So, how was that a good plan? "Even in the seminal Minnesota study, metabolic rate eventually rebounded to normal; of course the subjects had regained all of the fat they had lost as well for that to occur." It should be noted that some extremely obese folks tried doing this and damaged their metabolisms to where they couldn't lose excessive fat on very low calories because they developed insulin resistance. "One of my clients weighs 360 lbs and her BMR according to the the InBody is 2700 calories. The girl eats maybe 1200 calories a day and maintains that weight. Reversing insulin resistance by eating the proper foods and incorporating resistance training obviously helps. I am wondering if there is an approach to increasing calories systematically when working to reverse insulin resistance without gaining weight?" If you want more info on that, I suggest you contact Lyle, who runs that site.
  • Zangpakto
    Zangpakto Posts: 336 Member
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    Truthfully... no reason. Doctors even prescribe VLC diets. which is under BMR.

    Even a reported case of someone with a few vitamins and minerals solely living on fat for a year or something because he had so much to lose... And you know what? Maintained LBM....

    It's myths that MFP decides upon and mods here enforce. They are not part of the medical science community, never will be and yet they pretend it.
  • Mads1997
    Mads1997 Posts: 1,494 Member
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    Twinketta is right about losing your Lean Body Mass too. You will lose muscle, a lot more than you want to. That is another problem with radical cutting diets.

    You will lose lean muscle mass if you do extreme cardio and eat over your BMR too.
  • peachfigs
    peachfigs Posts: 831 Member
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    you could die
  • OddChoices
    OddChoices Posts: 244 Member
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    It is easy to breakdown muscle than breakdown fat. As someone mentioned it takes energy to metabolize fat and make it available to the body. Hence if you eat below BMR, your body will first "cannibalize" the easier fuel source before turning to the fat stores.
  • ThickMcRunFast
    ThickMcRunFast Posts: 22,511 Member
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    Oh, this thread.

    5WpTtBt.gif
  • babydiego87
    babydiego87 Posts: 905 Member
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    you could die
    cmon, i heard you'd lose a limb at most.
  • twinketta
    twinketta Posts: 2,130 Member
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    Twinketta is right about losing your Lean Body Mass too. You will lose muscle, a lot more than you want to. That is another problem with radical cutting diets.

    You will lose lean muscle mass if you do extreme cardio and eat over your BMR too.


    hmm!! elaborate on that one???
  • kimleroy
    kimleroy Posts: 50 Member
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    I'd just like to point out that while yes, it does take a very slight energy input to break down fat stores to be used as energy, you get a very large amount of energy out from it. So, biochemically speaking, you don't really need to have much available energy to break down fat because once you break down the first molecule, you get out enough energy to break down about 10 more.

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