Demystifying the BMR

EncoreUneAutreFois
EncoreUneAutreFois Posts: 42 Member
in Food and Nutrition
So I'm on the 1200 per day plan, and MFP says my BMR is 1290. Does that mean I can never eat over 1290 or I'll gain weight? How does exercise affect this? I'm a smart person, but my brain tends to shut down when it comes to numbers. Can someone please explain this to me without using math? Appreciate it!

Replies

  • mickeygirliegirl
    mickeygirliegirl Posts: 302 Member
    BMR is your Basal Metabolic Rate, which is the rate you burn calories if you did nothing but breathe and lay in bed. So you can eat more than the rate and still lose weight. You do not want to go too far under though because that is detrimental as well (can cause starvation mode).

    The more active you are will change your BMR. Someone who is sedentary will have a lower BMR than someone who is active (given height/weight is the same).

    Hope this helps.
  • cmriverside
    cmriverside Posts: 34,420 Member
    It's 90 calories. Isn't going to make much difference. But if your BMR is 1290, you need to eat way more than even 1290.
  • EncoreUneAutreFois
    EncoreUneAutreFois Posts: 42 Member
    If my BMR is 1290 and I need to eat over 1290, why did MFP tell me to eat 1200? I eat back my exercise cals, and I eat whenever I'm hungry, so no limiting food intake goin on here, I'm just trying to understand the science.
  • wolftrax
    wolftrax Posts: 50
    If your BMR is 1290 cals, the activity mark-up is 258 cals @.2 x BMR for a total of 1548 cals/day on average for a week..Most all of us are actually sedentary in the US because we are not as active as folks were in decades past..If you are running a jack-hammer on a road crew every day you could use a .55 mark-up for activity..
  • mickeygirliegirl
    mickeygirliegirl Posts: 302 Member
    Okay, I'm going to try to do this with math (but I will do it with even numbers). Let's say my BMR is 2000. And I want to lose around 2 lbs/week SAFELY. MFP is going to put my calories at 1200. (800 less than my BMR). So, in a week if I did no exercise and ate exactly 1200 calories each of those days then 800 x 7 days = 5600 calories burned which is about 1 1/2 in fat loss.

    If I have a BMR of 2000 and I burn 100 caloies to activity on top of the BMR, then I would need to eat 1300 calories to get to the deficit that is the minimum safe to lose weight. (1300-100 extra calories burned)

    If I have a BMR of 2000 and I burn 100 calories to activity and I eat 2000 calories, I am still eating less calories than what I burn. (2000-100 burned = 1900 calories which is less than my BMR of 2000)

    You do not NEED to eat over 1290, but you CAN eat over 1290 and lose weight.
  • EncoreUneAutreFois
    EncoreUneAutreFois Posts: 42 Member
    Awesome -- thank you!
  • cmriverside
    cmriverside Posts: 34,420 Member
    Okay, I'm going to try to do this with math (but I will do it with even numbers). Let's say my BMR is 2000. And I want to lose around 2 lbs/week SAFELY. MFP is going to put my calories at 1200. (800 less than my BMR). So, in a week if I did no exercise and ate exactly 1200 calories each of those days then 800 x 7 days = 5600 calories burned which is about 1 1/2 in fat loss.

    If I have a BMR of 2000 and I burn 100 caloies to activity on top of the BMR, then I would need to eat 1300 calories to get to the deficit that is the minimum safe to lose weight. (1300-100 extra calories burned)

    If I have a BMR of 2000 and I burn 100 calories to activity and I eat 2000 calories, I am still eating less calories than what I burn. (2000-100 burned = 1900 calories which is less than my BMR of 2000)

    You do not NEED to eat over 1290, but you CAN eat over 1290 and lose weight.

    This is wrong wrong wrong. You need to do some reading.
  • heybales
    heybales Posts: 18,842 Member
    If my BMR is 1290 and I need to eat over 1290, why did MFP tell me to eat 1200? I eat back my exercise cals, and I eat whenever I'm hungry, so no limiting food intake goin on here, I'm just trying to understand the science.

    Why? And no science involved, just math. In fact, science sadly lacking in recommendations for far too many.

    Because you selected an activity level of sedentary, right or wrong, and you selected weight loss goal of 1 or more lbs per week, and MFP stops subtracting for that actual weight loss at 1200 for reasons of safety.

    1290 BMR x 1.25 sedentary = 1612 maintenance NOT including exercise you have not done yet.
    1612 - 500 for 1 lb loss weekly = 1112 but MFP stops at 1200.

    And that is not eating at 1200, that is NETTING at 1200.
    If you eat at 1200, and start exercising say 500 cal avg daily burn, you just made the deficit rather unwise and unsafe (1200-500=700 left for body to use, when it would prefer to use 1200 about), defeating the whole purpose of staying at 1200.
  • mickeygirliegirl
    mickeygirliegirl Posts: 302 Member
    Okay, I'm going to try to do this with math (but I will do it with even numbers). Let's say my BMR is 2000. And I want to lose around 2 lbs/week SAFELY. MFP is going to put my calories at 1200. (800 less than my BMR). So, in a week if I did no exercise and ate exactly 1200 calories each of those days then 800 x 7 days = 5600 calories burned which is about 1 1/2 in fat loss.

    If I have a BMR of 2000 and I burn 100 caloies to activity on top of the BMR, then I would need to eat 1300 calories to get to the deficit that is the minimum safe to lose weight. (1300-100 extra calories burned)

    If I have a BMR of 2000 and I burn 100 calories to activity and I eat 2000 calories, I am still eating less calories than what I burn. (2000-100 burned = 1900 calories which is less than my BMR of 2000)

    You do not NEED to eat over 1290, but you CAN eat over 1290 and lose weight.

    This is wrong wrong wrong. You need to do some reading.

    Instead of being a jerk, why don't you explain it then?
  • treetop57
    treetop57 Posts: 1,578 Member
    Okay, I'm going to try to do this with math (but I will do it with even numbers). Let's say my BMR is 2000. And I want to lose around 2 lbs/week SAFELY. MFP is going to put my calories at 1200. (800 less than my BMR).

    MFP calculates the deficit off the Total Daily Energy Requirement (TDEE), not the BMR. As you said, BMR is what your body burns in a coma, just what your body requires to stay alive with no movement or digestion or thought. Your TDEE is the BMR times an activity factor that depends on how much you move around in your daily life. For most of us sedentary modern office workers, that's a factor of 1.2 to go from BMR to TDEE.

    2000 x 1.2 = 2400.

    Then MFP subtracts from there depending on your weight loss goal. A pound of fat is storage of 3500 extra calories. A week is seven days. So 1 pound per week is a deficit of 3500 calories in 7 days or a deficit of 500 calories per day. By the same logic, 2 pounds per week is a deficit of 1000 calories per day.

    For 2 pounds per week: 2400 - 1000 = 1400

    But many medical authorities believe an adult woman can't get all the various nutrient she needs if she nets less than 1200 calories a day. So for some one like the original poster, MFP is never going to set her net calorie goal at less than 1200 per day.

    So for the original poster, who said her BMR is 1290.

    TDEE = 1290 x 1.2 = 1548

    Normally for one pound per week, you'd just subtract 500 for a daily goal of 1048 . . . but that would be less than the 1200 minimum. So MFP says to net 1200 per day. That's only a 348 calorie daily deficit or about 1 pound every ten days, no matter whether she told it she wants to lose 1 lb a week or 2 lbs a week. MFP doesn't think it's safe for her to net less and lose faster.

    One more "but." Many people say never net less than your BMR or you will lose muscle instead of fat. In the original poster's case, following that advice would mean netting 1290 per day, a deficit of 258 a day, or about a 1/2 a pound a week.
  • heybales
    heybales Posts: 18,842 Member
    For most of us sedentary modern office workers, that's a factor of 1.2 to go from BMR to TDEE.

    2000 x 1.2 = 2400.

    Interestingly, about a month ago, MFP broke from the standard Sedentary being 1.2, and went to 1.25, probably to try to protect people from themselves.

    Or they had enough FitBit stats to see that those selecting Sedentary were really not as much as they thought.

    The other comment to the excellent description, MFP isn't calculating TDEE, as they don't include exercise in it. And all their other level multipliers are very much lower than standard TDEE calculators anyway.

    So even if you wanted to like include exercise in your activity level selection, and NOT eat back exercise, you'd be hitting a much lower estimated TDEE that doesn't match any other TDEE calculator.

    MFP activity levels and multiplier and effect on 1500 BMR
    Sedentary_____ 1.25 __ 1875
    Lightly Active___ 1.35 __ 2025
    Active________ 1.45 __ 2175
    Very Active_____ 1.55 __ 2325

    TDEE activity levels and multiplier and effect on 1500 BMR
    Sedentary_____ 1.2 ___ 1800
    Lightly active___ 1.375 _ 2063
    Mod. active____ 1.55 __ 2325
    Very active_____ 1.725 _ 2588
    Extra Active____ 1.9 ___ 2850
  • treetop57
    treetop57 Posts: 1,578 Member
    I hadn't noticed that they had changed the multiplier for sedentary. And thanks for clarifying TDEE. You're right of course. I didn't mention exercise above normal daily activities, which would be included in TDEE, but that MFP doesn't include in its calculations.
  • mickeygirliegirl
    mickeygirliegirl Posts: 302 Member
    Thanks for the explanations instead of just saying I was wrong wrong wrong and then telling me to go read. How helpful or supportive is that?

    I digress.

    I was mistaken in my math only in that I was confusing BMR for the (what I now know to be) TDEE that MFP figures out.

    Sorry for any confusion OP that I may have inadvertantly caused. I knew my math was technically right, I just used the wrong terminology for what I was trying to put across.
  • EncoreUneAutreFois
    EncoreUneAutreFois Posts: 42 Member
    I really appreciate all of your help, but I have to be honest -- as soon as I saw the numbers, my head shut down. So what I'm hearing is that I can eat below the BMR and lose weight, and I need to eat back my exercise calories, is that right?
  • heybales
    heybales Posts: 18,842 Member
    I really appreciate all of your help, but I have to be honest -- as soon as I saw the numbers, my head shut down. So what I'm hearing is that I can eat below the BMR and lose weight, and I need to eat back my exercise calories, is that right?

    If you eat back your exercise calories, that is commonly called on here NETting.

    Anyway, yes, you can NET below your BMR by eating back exercise calories and lose weight - just slower than it needs to be.

    And you'll have the issue when you reach goal weight, of having difficulting raising the calorie level without your body wanting to store the extra as fat because it's been operating below the level it wants to for so long.

    Faster weight loss and eating more.
    Slower weight loss and eating less.

    Hmmm, which shall it be?

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