Need clarification about BMR and TDEE

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salilsurendran
salilsurendran Posts: 9 Member
in Health and Weight Loss
I am 42 year old male, 170 lbs and 5' 9". When I go to most BMR calculators on the web ( for eg. https://dailyburn.com/life/health/how-to-calculate-bmr/ ) I enter my activity level and usually I enter exercise 5 times a week. Based upon my activity level it gives me a TDEE of 2575 calories and a BMR of 1661 calories. So let's say I exercise 5 times a week and each time I burn 500 calories should I assume that in order to maintain weight that I will have to eat 1661 + 500 calories or 2575 + 500 calories. Does the TDEE calculator account that I will be burning an extra 900 calories through exercise or is it that because of exercise that my body will just burn much more calories just surviving? So for eg. if I don't exercise at all in week I will burn 1661 * 7 calories. On the other hand, I exercise 5 times a week and each time burn 500 calories then in a week I burn 2575 * 7 + 500 * 5 (500 calories in each of the 5 exercise sessions) or will I burn 1671 * 7 + 500 * 5 calories?

Replies

  • Lietchi
    Lietchi Posts: 6,109 Member
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    A true TDEE calculator includes all your activity. So yes, it includes the exercise you entered.
    Some warnings though: that calculator had no idea what exercise you're doing, the intensity of it etc. So it's VERY approximate.
    Furthermore, it's not a good TDEE calculator in the sense that it only lets you enter exercise, but it doesn't ask what your activity level is outside of exercise. There is a big difference between a construction worker that doesn't exercise and an office worker that doesn't exercise, for example.

    Your BMR is what you burn just to be alive. Which is NOT what you burn when sedentary. Try it out, use that calculator to calculate your TDEE with little or no exercise, you should get a higher number than your BMR.
  • sijomial
    sijomial Posts: 19,811 Member
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    If you want a same every day calorie goal I would suggest a better TDEE site such as https://www.sailrabbit.com/bmr/
    That dailyburn one is very primitive - my sedentary daughter who is furloughed at home but does some gentle purposeful exercise would get a bigger calorie uplift than my son who works in construction 6 days a week!

    If you prefer a calorie goal that varies daily in line with your exercise then use the goal set up here. It will calculate your BMR, multiply it by your non-exercise activity level and then you choose a rate of weight loss (or to maintain weight or to gain weight). Log your exercise after the event to get a more nuanced estimate rather than a very vague daily average.

    This week my exercise sessions have varied enourmously from over 1900 for a multi-hour cycle ride to a couple of hundred calories of strength training so a daily average could be terribly hard to find.
  • kshama2001
    kshama2001 Posts: 27,897 Member
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    I just keep it simple and let MFP do the math and eat back some, but not all, of my exercise calories.

    https://www.myfitnesspal.com/account/change_goals_guided

    https://support.myfitnesspal.com/hc/en-us/articles/360032625391-How-does-MyFitnessPal-calculate-my-initial-goals-
  • salilsurendran
    salilsurendran Posts: 9 Member
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    Got it. One more question, if you go for a long walk for say 2 hours and burn 500 calories. And say you burnt 100 calories per hour just being sedentary. Do you subtract the 2 * 100 from the 500 before inputting your exercise calories, since you just burnt 300 extra calories due to exercise. Or does it not matter
  • lgfrie
    lgfrie Posts: 1,449 Member
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    salilsurendran wrote: »
    Got it. One more question, if you go for a long walk for say 2 hours and burn 500 calories. And say you burnt 100 calories per hour just being sedentary. Do you subtract the 2 * 100 from the 500 before inputting your exercise calories, since you just burnt 300 extra calories due to exercise. Or does it not matter

    Ah, you are bringing up the important issue of gross vs net exercise calories. If you want to attempt to be accurate about it, yes, you should use net exercise calories. The 100 per hour (or thereabouts) is something you already got from assuming a daily TDEE of 2400; it shouldn't be double counted. So in this case, you would just log the 300, which is your net exercise.
  • AnnPT77
    AnnPT77 Posts: 32,070 Member
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    salilsurendran wrote: »
    Got it. One more question, if you go for a long walk for say 2 hours and burn 500 calories. And say you burnt 100 calories per hour just being sedentary. Do you subtract the 2 * 100 from the 500 before inputting your exercise calories, since you just burnt 300 extra calories due to exercise. Or does it not matter

    You need to know whether the 500 calorie estimate is gross calories (includes RMR) or net calories (doesn't include RMR). Some sources of exercise estimates give you gross, others give you net. The MFP database gives you gross, so for a bit higher likelihood of accuracy, you'd subtract the sedentary calories. If you get the estimate from other sources, you need to figure out whether it's gross or net.

    For shorter-duration typical exercise, the difference isn't really numerically large enough to worry about, IMO. For long duration, not very intense exercise (such as slow walking for hours), it may be worth doing that arithmetic.
  • PAV8888
    PAV8888 Posts: 13,605 Member
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    Your net MFP exercise would be gross exercise calories LESS 1.25*BRM calories since the MFP sedentary is set to 1.25*BMR and assumes that you burn that during each of the day's 1440 minutes!

    So your intuition is correct; but you would have to deduct more than 1*BRM to arrive to true net calories for that time period.

  • kshama2001
    kshama2001 Posts: 27,897 Member
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    salilsurendran wrote: »
    Got it. One more question, if you go for a long walk for say 2 hours and burn 500 calories. And say you burnt 100 calories per hour just being sedentary. Do you subtract the 2 * 100 from the 500 before inputting your exercise calories, since you just burnt 300 extra calories due to exercise. Or does it not matter

    Or again, you could just use MFP as designed, log the time spent walking, and let MFP handle net v gross calories behind the scenes :)
  • PAV8888
    PAV8888 Posts: 13,605 Member
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    kshama2001 wrote: »
    Or again, you could just use MFP as designed, log the time spent walking, and let MFP handle net v gross calories behind the scenes :)

    I agree about using MFP as designed and (re)evaluating individual logging accuracy after an appropriate time period.

    But has there been an update in terms of MFP treading gross/net Cal correctly?

    A major source of the "inflated" burns MFP exercise is (in)famous for is, in my opinion, the simple fact that at LEAST 1.25*BMR (and if a user is set to other than sedentary/not very active even more than 1.25* BRM) Calories are shown as exercise burn to be eaten back when MFP fails to take into account the calories already assigned to the time period and uses gross calories for exercise.

    This is particularly hard hitting with low intensity low duration exercises and has contributed to a large degree to the "eat half" rule of thumb when it comes to MFP logged exercise.

    And, of course, when the "exercise" calories come from a connected device where integration works properly under normal circumstances (e.g. fitbit), the above (eat half rule) SHOULDN'T automatically apply because integration (when not messed with manually) correctly doesn't double count pre-assigned calories.
  • sijomial
    sijomial Posts: 19,811 Member
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    kshama2001 wrote: »
    salilsurendran wrote: »
    Got it. One more question, if you go for a long walk for say 2 hours and burn 500 calories. And say you burnt 100 calories per hour just being sedentary. Do you subtract the 2 * 100 from the 500 before inputting your exercise calories, since you just burnt 300 extra calories due to exercise. Or does it not matter

    Or again, you could just use MFP as designed, log the time spent walking, and let MFP handle net v gross calories behind the scenes :)

    Except it doesn't - it has taken the METS from gross calorie estimates such as the compendium of physical activities and hasn't bothered to add the programming to convert to a net calorie estimate.
    Not a huge problem if someone is exercising for short durations, big divergence for someone who does long exercise sessions.

    Personally I use a net calorie calculator and overwrite MFP's inflated walking estimates.
  • lgfrie
    lgfrie Posts: 1,449 Member
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    PAV8888 wrote: »
    kshama2001 wrote: »
    Or again, you could just use MFP as designed, log the time spent walking, and let MFP handle net v gross calories behind the scenes :)

    I agree about using MFP as designed and (re)evaluating individual logging accuracy after an appropriate time period.

    But has there been an update in terms of MFP treading gross/net Cal correctly?

    A major source of the "inflated" burns MFP exercise is (in)famous for is, in my opinion, the simple fact that at LEAST 1.25*BMR (and if a user is set to other than sedentary/not very active even more than 1.25* BRM) Calories are shown as exercise burn to be eaten back when MFP fails to take into account the calories already assigned to the time period and uses gross calories for exercise.

    This is particularly hard hitting with low intensity low duration exercises and has contributed to a large degree to the "eat half" rule of thumb when it comes to MFP logged exercise.

    And, of course, when the "exercise" calories come from a connected device where integration works properly under normal circumstances (e.g. fitbit), the above (eat half rule) SHOULDN'T automatically apply because integration (when not messed with manually) correctly doesn't double count pre-assigned calories.

    Though I don't have inside knowledge of their formulas, I agree with this. It's seemed to me for a long time that MFP's exercise calorie estimates are gross, not net. Doesn't matter much for 20 minutes of HIIT but it becomes extremely important with hour+ walks, low intensity cardio, and such. I don't trust their numbers at all - way too high, for anything I've tried to use them for. They are often at least double the watts/hr * 3.6 formula.
  • kshama2001
    kshama2001 Posts: 27,897 Member
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    PAV8888 wrote: »
    kshama2001 wrote: »
    Or again, you could just use MFP as designed, log the time spent walking, and let MFP handle net v gross calories behind the scenes :)

    I agree about using MFP as designed and (re)evaluating individual logging accuracy after an appropriate time period.

    But has there been an update in terms of MFP treading gross/net Cal correctly?

    A major source of the "inflated" burns MFP exercise is (in)famous for is, in my opinion, the simple fact that at LEAST 1.25*BMR (and if a user is set to other than sedentary/not very active even more than 1.25* BRM) Calories are shown as exercise burn to be eaten back when MFP fails to take into account the calories already assigned to the time period and uses gross calories for exercise.

    This is particularly hard hitting with low intensity low duration exercises and has contributed to a large degree to the "eat half" rule of thumb when it comes to MFP logged exercise.

    And, of course, when the "exercise" calories come from a connected device where integration works properly under normal circumstances (e.g. fitbit), the above (eat half rule) SHOULDN'T automatically apply because integration (when not messed with manually) correctly doesn't double count pre-assigned calories.
    lgfrie wrote: »
    Though I don't have inside knowledge of their formulas, I agree with this. It's seemed to me for a long time that MFP's exercise calorie estimates are gross, not net. Doesn't matter much for 20 minutes of HIIT but it becomes extremely important with hour+ walks, low intensity cardio, and such. I don't trust their numbers at all - way too high, for anything I've tried to use them for. They are often at least double the watts/hr * 3.6 formula.

    Hmm, interesting. @Alex: can you shed some light on this? Are MFP's exercise calories Gross? This seems like a programming error that should be addressed.

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