eating below BMR

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sheldonklein
sheldonklein Posts: 854 Member
in Health and Weight Loss
I frequently see warnings against eating below BMR. I'm baffled by the logic. My body doesn't have seperate buckets of energy stores for the different conceptual elements of TDEE. A calorie deficit is a calorie deficit. Am I missing something, or is this just some confused folk wisdom?

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  • SideSteel
    SideSteel Posts: 11,068 Member
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    In my opinion you could probably come up with a list of reasons why eating at a very large energy deficit isn't a good idea. Things like maintaining muscle, long term diet adherence, nutrient sufficiency, satiety, gym performance, and you might even be able to make an argument about rates of AT but having said all of that, I don't believe that BMR is a magical number that you should never eat below.

    If you ARE eating below BMR, it would seem reasonable to me that it's a result of very low activity (gap between TDEE and BMR is too small).
  • cwolfman13
    cwolfman13 Posts: 41,871 Member
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    From what I've researched, there are several issues in RE to having too large a calorie deficit in general...one of which is more loss of lean mass than is necessary...another is that this really stresses the body and wreaks havoc on your hormones and cortisol levels, etc which in turn makes your body not work quite as well as it should, including your metabolism overall. Most people would also have issue meeting general nutrient requisites.

    In my research, the less weight you have to lose, the bigger issue low calories and whatnot are.

    For myself, I've worked really hard to get where I am now...lost 40+ Lbs and have regained my fitness, etc...I'm about 17% BF and starting another cut to get down to 10% or so...I've worked really hard to get the body I have now...there's no way I would deliberately do a VLCD just to knock off those last 10-15 Lbs or so to get as lean as I want to get...it would compromise everything I've put into this for the past two years.

    IMO, outside of being obese and needing to drop weight quickly as per doctors orders or whatever...I think eating VLCD and whatnot is simply ignorance of the entire process and most of those types are likely to fail long run because they simply have no interest in that actual process and how to actually be healthy and fit. Just MO.

  • LazyButHealthy
    LazyButHealthy Posts: 257 Member
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    Um.

    What's a BMR and what's TDEE?
  • cwolfman13
    cwolfman13 Posts: 41,871 Member
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    LazyButHealthy wrote: »
    Um.

    What's a BMR and what's TDEE?

    BMR - Basal Metabolic Rate...the rate at which you "burn" calories by the act of merely existing on this planet.

    TDEE - Total Daily Energy Expenditure...your total energy requisites...your maintenance calories...your TDEE is your BMR plus your daily hum drum plus any exercise, etc...the total energy (calories) your body requires to maintain the status quot.

    When you eat less than your TDEE you are in an energy (calorie) deficit...your body has to make up for that lost energy and does so my dipping into fat stores...thus when you eat below your TDEE, you lose weight.

    Conversely, when you eat in excess of your energy requirements...aka TDEE...that excess energy gets stored for later use as body fat...
  • sheldonklein
    sheldonklein Posts: 854 Member
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    I really wasnt asking about VLCD. My BMR is approx. 2000 kcal. Lots of room between there and VLCD. I just get the sense that there are some who are giving (or following) bad advice in the belief that BMR has some bodily correlate.
  • peachyfuzzle
    peachyfuzzle Posts: 1,122 Member
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    sheldonklein wrote: »
    I frequently see warnings against eating below BMR. I'm baffled by the logic. My body doesn't have seperate buckets of energy stores for the different conceptual elements of TDEE. A calorie deficit is a calorie deficit. Am I missing something, or is this just some confused folk wisdom?

    If you're eating below your BMR, then you're not even taking in the amount of calories your body burns while keeping itself alive.

    There isn't a second energy store, or anything like that. There is the amount of calories your body burns naturally without doing absolutely anything else (BMR), and then there is TDEE which is BMR + the energy expended by normal daily activities. The only people in the world who would ever be at their BMR for maintenance are braindead vegetables hooked up to machines in the hospital considering TDEE rises even if you're an utter couch potato only getting up to go to the bathroom, or just changing seating positions.

    Eating below your BMR will often cause stuff like headaches, lightheadedness, irritability, fatigue, etc. In extreme cases like with that of Anorexia, it will cause serious health problems, and even death.

    This is why is is suggested to find your TDEE, and eat at 10 - 25% (at the extreme end) below that to safely lose weight. At that point, you're still giving your body enough to live, plus some, but you're not consuming as many calories as you're using per day through your normal activity.
  • TimothyFish
    TimothyFish Posts: 4,925 Member
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    People have been fasting for religious reasons for thousands of years, and for most part, the people who do tend to be healthier than those who don't. I doubt that eating below BMR is going to hurt anyone, as long as they don't do it for long periods of time.
  • cwolfman13
    cwolfman13 Posts: 41,871 Member
    edited November 2014
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    sheldonklein wrote: »
    I really wasnt asking about VLCD. My BMR is approx. 2000 kcal. Lots of room between there and VLCD. I just get the sense that there are some who are giving (or following) bad advice in the belief that BMR has some bodily correlate.

    Then put it in context...most of these comments get directed towards young women who have very little weight to lose and very low BMR's and they're working out for hours daily and eating 800 or less calories....

    Just sayin'....put the comments in context...I don't think anyone is worried about 2000 calories.

    I would also add that as anything else, BMR is an estimate...I don't think there's some magic number for which we all turn into a pumpkin or something if we don't eat that exact number. What I think is important is that people know and understand how to properly fuel their bodies for weight control as well as fitness. By and large though, people would rather just starve their bodies and crash their diets in order to try to circumvent the actual process...
  • LazyButHealthy
    LazyButHealthy Posts: 257 Member
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    cwolfman13 wrote: »
    LazyButHealthy wrote: »
    Um.

    What's a BMR and what's TDEE?

    BMR - Basal Metabolic Rate...the rate at which you "burn" calories by the act of merely existing on this planet.

    TDEE - Total Daily Energy Expenditure...your total energy requisites...your maintenance calories...your TDEE is your BMR plus your daily hum drum plus any exercise, etc...the total energy (calories) your body requires to maintain the status quot.

    When you eat less than your TDEE you are in an energy (calorie) deficit...your body has to make up for that lost energy and does so my dipping into fat stores...thus when you eat below your TDEE, you lose weight.

    Conversely, when you eat in excess of your energy requirements...aka TDEE...that excess energy gets stored for later use as body fat...

    Thanks!

  • josul75
    josul75 Posts: 41 Member
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    Quick question: If it is unhealthy to eat below your BMR, then why does MFP regularly set people's calories to below this level?

    For instance, my BMR is 1604 and mt TDEE is 1924, but MFP has set my daily calories as 1220.
  • cwolfman13
    cwolfman13 Posts: 41,871 Member
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    josul75 wrote: »
    Quick question: If it is unhealthy to eat below your BMR, then why does MFP regularly set people's calories to below this level?

    For instance, my BMR is 1604 and mt TDEE is 1924, but MFP has set my daily calories as 1220.

    For one thing, you probably don't understand that you're supposed to eat back calories with the MFP method...so if you exercised then you would eat more. For another, MFP is just a calculator...it's just giving you a number based on what YOU said you wanted to do...it assumes you have a brain...MFP is not a brain...it's just a calculator. 1200 is the lowest it will go based on the most aggressive weight loss approach...i.e. you probably put sedentary (and you're probably not actually sedentary) and you probably said you wanted to lose 2 lbs per week.

    I would also add that you BMR is probably lower than that. Most calculators do a very generic calculation for BMR as per your body weight...this takes into account both you lean mass and fat mass...calculators that only take into account your lean mass are more accurate...you don't need to fuel your fat...you need to fuel your lean mass. In reality, your BMR is likely more like 1300 - 1400 calories.
  • WalkingAlong
    WalkingAlong Posts: 4,926 Member
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    sheldonklein wrote: »
    I frequently see warnings against eating below BMR. I'm baffled by the logic. My body doesn't have seperate buckets of energy stores for the different conceptual elements of TDEE. A calorie deficit is a calorie deficit. Am I missing something, or is this just some confused folk wisdom?

    It is confused folk wisdom. You're right about no buckets and faulty logic.
  • josul75
    josul75 Posts: 41 Member
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    Well, I don't do any sort of planned exercise, just usual day to day activities and I have a desk job, so I just went by MFP's sedentary criteria on that one. The next option down was exercise three times a week, which I don't do.

    I actually input 1.5 lb a week weight loss and that's what I got. I'm not finding sticking to the calories too hard, just wondered about the whole eating under BMR type thing.
  • josul75
    josul75 Posts: 41 Member
    edited November 2014
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    Woops, double post!
  • nosebag1212
    nosebag1212 Posts: 621 Member
    edited November 2014
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    there's nothing wrong with eating below your BMR as long as you're getting adequate protein and EFA's, that said you shouldn't ever have to go below it unless you're deliberately doing a massive deficit, or you're legitimately a couch potato. Because if you exercise even just 3-4 x per week your TDEE will be well above your bmr by default, and this isn't even taking into account calories burned by NEAT which can have a huge effect on your overall TDEE.
  • WalkingAlong
    WalkingAlong Posts: 4,926 Member
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    nosebag1212 wrote: »
    there's nothing wrong with eating below your BMR as long as you're getting adequate protein and EFA's, that said you shouldn't ever have to go below it unless you're deliberately doing a massive deficit, or you're legitimately a couch potato. Because if you exercise even just 3-4 x per week your TDEE will be well above your bmr by default, and this isn't even taking into account calories burned by NEAT which can have a huge effect on your overall TDEE.

    But then MFP forum wisdom would say you have to 'eat back' so exercise can't contribute to your deficit.

    NEAT calories don't always have a huge effect. My BMR is maybe 1300. My NEAT is maybe 20% of that, so 260 more.

  • lemurcat12
    lemurcat12 Posts: 30,886 Member
    edited November 2014
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    sheldonklein wrote: »
    I frequently see warnings against eating below BMR. I'm baffled by the logic. My body doesn't have seperate buckets of energy stores for the different conceptual elements of TDEE. A calorie deficit is a calorie deficit. Am I missing something, or is this just some confused folk wisdom?

    I think it's a shorthand or confusion of don't eat too extreme a deficit. Sometimes BMR is a good measure of a reasonable deficit (for me eating at BMR would probably be too much of a deficit these days, and I therefore eat well above my BMR, although at a deficit), but for others--such as those who are largely sedentary or sufficiently large than their BMR is quite high--it's not and it's fine to eat below BMR IMO (for the reasons you note, among others). I did when I started.

    Edit: The point someone else made above about how calculator estimates of your BMR are likely to be too high if you don't have an accurate body fat percentage and need to lose a decent amount of weight is correct also. That's another reason why I wasn't concerned about eating below BMR when I started. I didn't know my BMR with any accuracy. It's basically a theoretical concept--what would I burn if I were completely inactive. Who knows? I'm not. It's irrelevant, except as a way to calculate TDEE.
  • yarwell
    yarwell Posts: 10,477 Member
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    sheldonklein wrote: »
    I frequently see warnings against eating below BMR. I'm baffled by the logic. My body doesn't have seperate buckets of energy stores for the different conceptual elements of TDEE. A calorie deficit is a calorie deficit. Am I missing something, or is this just some confused folk wisdom?

    You are not missing anything, you can relax.

    Anyone plugging in "sedentary" and 1 lb/week to MFP will get a calorie goal below their BMR, it's just maths.

  • yarwell
    yarwell Posts: 10,477 Member
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    josul75 wrote: »
    Quick question: If it is unhealthy to eat below your BMR, then why does MFP regularly set people's calories to below this level?

    Net calories = 1.2 * BMR - 500 for sedentary and 1 lb/week

    So anyone with a BMR below 2500 who is sedentary gets a net calorie goal below their BMR at a target loss rate of 1 lb/week.

    Sort of implies it isn't unhealthy I guess.

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