Is it bad to eat far below your BMR?

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jardane1
jardane1 Posts: 58 Member
in Health and Weight Loss
I have done the calculations and my BMR is around 3740 *i am 452 lb and 6'4 tall*. I want to lose 2 lbs a week so i need to cut out 1000 calories so my normal intake should be 2740. Lately i have been doing a ton of walking, between 3 and 4 miles a day and the calories burned walking are around 1000 calories.

Here are my questions
1. should i be eating back the calories i burn when walking/exercising?
2. Is there a harm in eating far below your daily limit like 500 to 1000 calories below?
3. Is starvation mode a real thing or just something people believe?
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Replies

  • bpetrosky
    bpetrosky Posts: 3,911 Member
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    In your situation, eating below your BMR occasionally is not a problem unless you have an underlying health condition such as diabetes.

    Ideally, if you follow the NEAT calculation used by MFP (sedentary) and with a 2 lb/wk loss goal, you should be just fine. That should set you at about a 1000 cal deficit. In your case, eating back the calories from exercise should be optional (if you feel hungry, use them, many people use 50% to allow for overestimating the calories from exercise).

    Starvation mode is a myth, you won't gain fat by underating. The body doesn't start "starving" after a few hours without food, it takes a severe prolonged situation to trigger the metabolic collapse that is considered starvation. That doesn't mean there aren't harms to undereating though, and good nutrition helps avoid those harms.
  • jardane1
    jardane1 Posts: 58 Member
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    Thanks, there are times when i am not hungry and i have like 800 calories left in the day and i get worried that if i don't eat them it would be bad. Do you think my 2740 calories sounds about right for someone who is 452lb 6'4 and 29 years of age? I have a desk job and try to walk as much as i can but i would say i am still in the sedentary range.
  • DemoraFairy
    DemoraFairy Posts: 1,806 Member
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    I think you mean your TDEE is 3,740, not your BMR. Your BMR is what you'd burn if you stayed in bed all day, your TDEE is what you burn in a normal day with moving, walking, talking, eating, etc. I get your BMR as being 3,121.
  • Need2Exerc1se
    Need2Exerc1se Posts: 13,576 Member
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    It's unlikely to be a problem at your size. It's usually only a problem when you are closer to goal and do it for prolonged periods of time.
  • SonicKrunch
    SonicKrunch Posts: 192 Member
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    You will be fine however one thing is necessary. Get at least 120-140g of protein everyday(at 2700 that shouldn't be a problem but you need to be eating whole foods) and get good healthy fats around 50-60g a day(salmon, nuts are great sources). The rest can be carbs. You can eat more than these numbers too if you want like up to 200g protein and 80-90g of fat but just stay within your caloric setup.
  • afatpersonwholikesfood
    afatpersonwholikesfood Posts: 577 Member
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    Put your info into MFP and set it for a loss of 2 lbs per week. How many calories does it give you? Remember that this is a lifelong thing, and you shouldn't do anything to take the weight off that you wouldn't want to do for the rest of your life. Too much deprivation isn't good for your physical or your mental health. 2,700 does sound pretty low to me for a guy your size.



  • JakeBrownVB
    JakeBrownVB Posts: 399 Member
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    DemoraFairy wrote: »
    I think you mean your TDEE is 3,740, not your BMR. Your BMR is what you'd burn if you stayed in bed all day, your TDEE is what you burn in a normal day with moving, walking, talking, eating, etc. I get your BMR as being 3,121.

    The guy is 452lbs at 6"4, I can very easily believe his BMR is 3,740.

    OP, in your case eating below your BMR will not be a bad thing. Stick to your plan it sounds solid.
  • FitOldMomma
    FitOldMomma Posts: 790 Member
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    If you are walking 4 to 5 miles each day, perhaps you should change the activity level to 'lightly active' in the settings. This way you will get a more accurate daily calorie target.
  • astralpictures
    astralpictures Posts: 218 Member
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    SonicKrunch wrote: »
    You will be fine however one thing is necessary. Get at least 120-140g of protein everyday(at 2700 that shouldn't be a problem but you need to be eating whole foods) and get good healthy fats around 50-60g a day(salmon, nuts are great sources). The rest can be carbs. You can eat more than these numbers too if you want like up to 200g protein and 80-90g of fat but just stay within your caloric setup.

    Why is it "necessary" to eat that specific amount of protein and "healthy" fat? In terms of weight loss, it doesn't technically matter what your macros are as long as you're eating under maintenance, and you certainly don't need to fit in specific foods like salmon and nuts. And if you're going to talk macros, wouldn't it make sense to provide a percentage ratio instead of a concrete number that may work for you but not others? I certainly don't need 140g of protein a day. If I was concentrating on muscle gains and bulking instead of deficit maybe.

    Usually when people worry about eating under BMR it is because their BMR is a lot lower, and the small amount of calories may not be providing adequate nutrients to meet micros. At 2000+ calories, this shouldn't be much of a concern unless you're eating 2500 calories of cupcakes (you'll still lose weight, but will end of vitamin and mineral deficient in the long term).
  • Lasmartchika
    Lasmartchika Posts: 3,440 Member
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    JakeBrownVB wrote: »
    DemoraFairy wrote: »
    I think you mean your TDEE is 3,740, not your BMR. Your BMR is what you'd burn if you stayed in bed all day, your TDEE is what you burn in a normal day with moving, walking, talking, eating, etc. I get your BMR as being 3,121.

    The guy is 452lbs at 6"4, I can very easily believe his BMR is 3,740.

    OP, in your case eating below your BMR will not be a bad thing. Stick to your plan it sounds solid.

    According to Scooby his BMR is 3,121 and his TDEE at moderately active (since he says he walks a lot) would be 4,838 and TDEE-20% he would have to eat 3,870 calories to lose 1.9 lbs/wk.

    OP, where did you get your number? Have you let MFP give you your numbers by choosing 2lbs/wk loss instead?
  • jardane1
    jardane1 Posts: 58 Member
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    I think i will stick with 2700 calories a day and then do my walking and eat the 1000 calories i burn from that. If i don't feel hungry and i have a lot of calories left over i think i feel better about that.
  • astralpictures
    astralpictures Posts: 218 Member
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    Be careful with eating back the 1000 calories from walking. You may not be actually burning that much, so a lot of people here say they eat back half of their burn to be safe.
  • freeoscar
    freeoscar Posts: 82 Member
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    1000 calories from 3-4 miles of walking sounds extremely high. I'm guessing that takes you around 1hr, 1hr 20 minutes, which is more likely a burn of half that or probably even less than that.
  • jardane1
    jardane1 Posts: 58 Member
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    Sounds wise, but like i said i am always quite a bit under so it should all work out. It sucks how slow weight loss is.
  • Chrysalid2014
    Chrysalid2014 Posts: 1,038 Member
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    astralpictures wrote: »
    SonicKrunch wrote: »
    You will be fine however one thing is necessary. Get at least 120-140g of protein everyday(at 2700 that shouldn't be a problem but you need to be eating whole foods) and get good healthy fats around 50-60g a day(salmon, nuts are great sources). The rest can be carbs. You can eat more than these numbers too if you want like up to 200g protein and 80-90g of fat but just stay within your caloric setup.

    Why is it "necessary" to eat that specific amount of protein and "healthy" fat? In terms of weight loss, it doesn't technically matter what your macros are as long as you're eating under maintenance, and you certainly don't need to fit in specific foods like salmon and nuts. And if you're going to talk macros, wouldn't it make sense to provide a percentage ratio instead of a concrete number that may work for you but not others? I certainly don't need 140g of protein a day. If I was concentrating on muscle gains and bulking instead of deficit maybe.

    Usually when people worry about eating under BMR it is because their BMR is a lot lower, and the small amount of calories may not be providing adequate nutrients to meet micros. At 2000+ calories, this shouldn't be much of a concern unless you're eating 2500 calories of cupcakes (you'll still lose weight, but will end of vitamin and mineral deficient in the long term).

    That depends on whether a person wants to lose fat or just "weight", and if they want to remain healthy while doing so. A certain proportion of protein in relation to bodyweight is necessary to preserve LBM in a calorie deficit. And some micronutrients are fat soluble so you need the fats to assimilate them properly.
    I actually think Sonic's calculations are too low for OP. @SonicKrunch what formula did you use? The numbers you quoted for protein/fats are the same as my goals (using this guide), and I weigh 210...
    http://blog.myfitnesspal.com/a-beginners-guide-to-protein/
  • senecarr
    senecarr Posts: 5,377 Member
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    Agree with Lasmartchika and DemoraFairy. IIFYM's TDEE calculator says to be have a BMR of 3700, he'd need to be 20 years old with a 25% body fat, at 6'4" and 452.
  • astralpictures
    astralpictures Posts: 218 Member
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    Chrysalid2014 wrote: »
    That depends on whether a person wants to lose fat or just "weight", and if they want to remain healthy while doing so. A certain proportion of protein in relation to bodyweight is necessary to preserve LBM in a calorie deficit. And some micronutrients are fat soluble so you need the fats to assimilate them properly.
    I actually think Sonic's calculations are too low for OP. @SonicKrunch what formula did you use? The numbers you quoted for protein/fats are the same as my goals (using this guide), and I weigh 210...
    http://blog.myfitnesspal.com/a-beginners-guide-to-protein/

    So you're claiming that if I'm in a deficit but not eating enough protein and fat, that I will lose weight from other sources more than fat? Funny how I eat more carbs than fat and protein, yet still have been losing mostly fat and still have muscles on my frame. You'd think I'd be nothing but bone and fat now! You have fat storage for a reason, for your body to use as fuel when you're in a calorie deficit. It isn't going to turn to eat mostly muscle instead if you're not eating a massive amount of protein. If you're in deficit, you're going to lose some muscle anyways, but not as drastically as you make it out. I'm also pretty sure that with the typical Western diet, most people are getting plenty of protein and fat without even trying.
  • SonicKrunch
    SonicKrunch Posts: 192 Member
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    astralpictures wrote: »
    SonicKrunch wrote: »
    You will be fine however one thing is necessary. Get at least 120-140g of protein everyday(at 2700 that shouldn't be a problem but you need to be eating whole foods) and get good healthy fats around 50-60g a day(salmon, nuts are great sources). The rest can be carbs. You can eat more than these numbers too if you want like up to 200g protein and 80-90g of fat but just stay within your caloric setup.

    Why is it "necessary" to eat that specific amount of protein and "healthy" fat? In terms of weight loss, it doesn't technically matter what your macros are as long as you're eating under maintenance, and you certainly don't need to fit in specific foods like salmon and nuts. And if you're going to talk macros, wouldn't it make sense to provide a percentage ratio instead of a concrete number that may work for you but not others? I certainly don't need 140g of protein a day. If I was concentrating on muscle gains and bulking instead of deficit maybe.

    Usually when people worry about eating under BMR it is because their BMR is a lot lower, and the small amount of calories may not be providing adequate nutrients to meet micros. At 2000+ calories, this shouldn't be much of a concern unless you're eating 2500 calories of cupcakes (you'll still lose weight, but will end of vitamin and mineral deficient in the long term).

    As Chrysalid said as well. If he wants to lose weight, sure eat 1g of protein and see how that works for him. He'll end up a rail thin 6'4 guy with no energy and no muscle. My 120-140g is based on 0.75g/lb of lean body weight. At 6'4 he should probably weigh around 180-200 pounds. It's actually low as Chrysalid said but there are a ton of people on here that really just don't eat enough protein so even getting 120g is better than some people on here do and will at least maintain most of his muscle mass.

    As for you not needing 140g, that depends on your height but from your picture you look to be about 5'8-9 at most(sorry if that's not accurate) so a normal weight would be 140-170 depending on what you want to look like. So you are correct you may not need 140g, though as you said if you were on a bulk you would want that much or a little more. I'm 5'10 and I get about 170 or a little more on my workout days and try to get about 120 on my off days.
  • astralpictures
    astralpictures Posts: 218 Member
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    I'm about 5'7" - 5'8", and I take in about 50 - 75 grams of protein daily on average. I've had no issues wasting away. Only consuming 1g of protein daily is very unlikely with most people's diets, so is a non-factor.

    My point was that while he may reach those protein levels since his calorie allowance is much higher than someone like me, it isn't a necessary to losing weight. There is no way to completely prevent some muscle loss while cutting, as far as I know. But it isn't as dire as losing all muscle either since almost everyone consumes a lot more protein than you'd think (unless you're a vegetarian/vegan and not trying to find other sources than meat).
  • Kst76
    Kst76 Posts: 935 Member
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    1000 calories sounds about tight for a 450 pound person. 3-4 miles is what, an hour - 90 minute walk Op? I am 174 pound and I burn 300 calories in 60 minutes walking.

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