If Body Fat % affects cals burned...cals burned calculator q

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mollydubs
mollydubs Posts: 205 Member
in Fitness and Exercise
The standard plug ins for calories-burned calculators are sex, weight, height, and minutes spent. But we know body fat % affects how many calories you burn when you exercise (the leaner you are, the more you burn) so...is there any online calculator or formula that adds your body fat % to the equation? Or is it not quite so straight forward? Any fitness gurus wanna help a girl out?

I'm super lean (according to body fat % calculators) and I'm wondering just how far off - or not - these calorie burn calculators may be...But I have no interest in a HRM ;)
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  • Crazy4Healthy
    Crazy4Healthy Posts: 626 Member
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    That is a very interesting question and one I would like to hear the answer for. I was wondering the same thing since I'm realizing recently that my Body Media Fit has not changed much since I started wearing it and I know my body fat % has gone down and I have more muscle mass. Since muscle burns more, would be nice if it somehow factored that into my daily burn.

    Can't wait to hear what people have to say.... nice post. :)
  • meshashesha2012
    meshashesha2012 Posts: 8,326 Member
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    this one does
    http://www.fat2fitradio.com/tools/bmr/
  • treetop57
    treetop57 Posts: 1,578 Member
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    this one does
    http://www.fat2fitradio.com/tools/bmr/

    It does for BMR, not for extra calories burned due to exercise. But for all I know, the only difference is to BMR, and the exercise calories are not a function of fat percentage. Good question, OP!
  • mollydubs
    mollydubs Posts: 205 Member
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    Hmm. Let me elaborate maybe.

    Gym machines do not give accurate calories-burned read outs, as we've all sooner or later discovered. They know our weight (as long as we enter it) so we know it's not just weight alone that affects calories burned during exercise. And we know that people with lower body fat % burn more calories doing the same exercises as those with higher body fat %.

    Sooooo, why no online calculators to take this into account? Is it just not that clear a science? (I'll admit, I have no grasp of science. In every single aspect of the term "science.")
  • glittersoul
    glittersoul Posts: 671
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    http://www.myfitnesspal.com/topics/show/216471-does-body-fat-affect-calories-burned

    Here is another thread to a similar question
  • katydid25
    katydid25 Posts: 199 Member
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    I saw this thread yesterday:
    http://www.myfitnesspal.com/topics/show/548645-setup-polar-hrm-for-more-accurate-calorie-burn-for-known-bmr

    It explains how to set the information in a heart rate monitor to get a more accurate number of calories burned when your body fat % is also taken into consideration. You basically figure the typical BMR of someone of your age, height and weight. Then do it a second time leaving out your age, but entering in your body fat percentage. Then a third time with age, height and weight, but you adjust the age until that BMR matchs the BMR you were given when you left of your age but included your body fat.

    So maybe that would also be the age you'd enter on the machines you use instead of your actual age to get a better calorie readout?
  • treetop57
    treetop57 Posts: 1,578 Member
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    I saw this thread yesterday: http://www.myfitnesspal.com/topics/show/550679-if-body-fat-affects-cals-burned-cals-burned-calculator-q

    That's a link to the thread we are on right now!
  • katydid25
    katydid25 Posts: 199 Member
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    I saw this thread yesterday: http://www.myfitnesspal.com/topics/show/550679-if-body-fat-affects-cals-burned-cals-burned-calculator-q

    That's a link to the thread we are on right now!


    Sorry about that! Thanks for pointing it out though :) It's corrected now!
  • treetop57
    treetop57 Posts: 1,578 Member
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    It explains how to set the information in a heart rate monitor to get a more accurate number of calories burned when your body fat % is also taken into consideration. You basically figure the typical BMR of someone of your age, height and weight. Then do it a second time leaving out your age, but entering in your body fat percentage. Then a third time with age, height and weight, but you adjust the age until that BMR matchs the BMR you were given when you left of your age but included your body fat.

    So I went here (http://www.fat2fitradio.com/tools/bmr/) and tried that method.

    With my actual information, it tells me that my "Harris-Benedict Formula" BMR is 2087. This is the one that uses age, but not body fat composition. With my actual information, my "Katch-McArdle Formula" BMR is 2108. This is the one that uses BF% but not age.

    So I go back and reduce my age by three years and Harris-Benedict is 2107 and Katch-McArdle is still 2108. So if I'm understanding all this correct, I'm 51 but I have the body fat percentage typical of a 48 year-old. Woohoo!

    Of course the other way to look at this is that even with my correct age, the two formulas differ by a grand total of 21 calories. Even I were very active, this is a difference of about 30 calories a day in estimated total daily energy expenditure.

    (3500 calories/lb)/(30 calories/day) means this difference will result in an extra pound of fat loss every 117 days. Again I say, "Woohoo!"

    I'm concluding that I'm too close to average for any of this to matter for me.
  • stayxtrue
    stayxtrue Posts: 1,190 Member
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    You could always buy a HRM which takes into account your BF%

    I know that mine has Weight, Sex, age, height, BF% this is going to give you the closest calories burned
  • katydid25
    katydid25 Posts: 199 Member
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    So if you find the age that gives you the same BMR as the equations that use body fat percentage instead of age, you are finding the age which has a body fat composition similar to yours. Give new meaning to "You've got the body of 25 year old"!

    You make a good point! Unfortunately, thats not the case for me. It's more along the lines of, "Oh great... you have the metabolism of a 64 year old..." Someday, though. Someday.
    Do the machines ask ones age? The exercise calculator on MFP does not, so this method definitely wouldn't work for that!

    The machines do ask for your age. Unfortunately the only way I could think of use this method with the calculators on MFP would be change your age on your profile. (In which case, people might see my profile and acknowledge how great I look for a 64 year old??)
  • ninerbuff
    ninerbuff Posts: 48,668 Member
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    There are so many variables to metabolism that you won't really get a truly accurate reading unless you have a Exercise metabolic test done. That would include a VO2 max test, an aerobic base test and an LT (lactate threshold) test.
    Raising you RMR is the most important thing you can do though since about 75% of your fat calories are burned at rest.

    A.C.E. Certified Personal & Group FitnessTrainer
    IDEA Fitness member
    Kickboxing Certified Instructor
    Been in fitness for 28+ years and have studied kinesiology and nutrition
  • mollydubs
    mollydubs Posts: 205 Member
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    That post is all sorts of wacky. I wasn't far off on what I thought my bf% was, but apparently it means I have to go 8 years older to get the same bmr needs. Which seems...odd. Right? Do older people have naturally lesser bf%?
  • stayxtrue
    stayxtrue Posts: 1,190 Member
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    There are so many variables to metabolism that you won't really get a truly accurate reading unless you have a Exercise metabolic test done. That would include a VO2 max test, an aerobic base test and an LT (lactate threshold) test.
    Raising you RMR is the most important thing you can do though since about 75% of your fat calories are burned at rest.

    A.C.E. Certified Personal & Group FitnessTrainer
    IDEA Fitness member
    Kickboxing Certified Instructor
    Been in fitness for 28+ years and have studied kinesiology and nutrition

    this i interesting and I seriously want to look into getting this done. However I have no idea who would be able to do this one for me
  • treetop57
    treetop57 Posts: 1,578 Member
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    That post is all sorts of wacky. I wasn't far off on what I thought my bf% was, but apparently it means I have to go 8 years older to get the same bmr needs. Which seems...odd. Right? Do older people have naturally lesser bf%?

    The equations assume that older people have higher BF%.
  • mollydubs
    mollydubs Posts: 205 Member
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    That post is all sorts of wacky. I wasn't far off on what I thought my bf% was, but apparently it means I have to go 8 years older to get the same bmr needs. Which seems...odd. Right? Do older people have naturally lesser bf%?

    The equations assume that older people have higher BF%.

    That's what I would assume too. Which is why I find my results of that little test kinda puzzling. But as you pointed out with yours, it is only about a 30 calorie difference. I guess I'll survive!
  • treetop57
    treetop57 Posts: 1,578 Member
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    . . .

    Raising you RMR is the most important thing you can do though since about 75% of your fat calories are burned at rest.

    A.C.E. Certified Personal & Group FitnessTrainer
    IDEA Fitness member
    Kickboxing Certified Instructor
    Been in fitness for 28+ years and have studied kinesiology and nutrition

    I know that increasing lean muscle mass increases resting metabolic rate. What else does? I read an article that was way above my head that was advocating high intensity interval training (HIIT) because somehow it adds mitochondria (or increases the activity of mitochondria), so even the muscle I already have will burn more. Is that the sort of thing you recommend?
  • heybales
    heybales Posts: 18,842 Member
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    The standard plug ins for calories-burned calculators are sex, weight, height, and minutes spent. But we know body fat % affects how many calories you burn when you exercise (the leaner you are, the more you burn) so...is there any online calculator or formula that adds your body fat % to the equation? Or is it not quite so straight forward? Any fitness gurus wanna help a girl out?

    I'm super lean (according to body fat % calculators) and I'm wondering just how far off - or not - these calorie burn calculators may be...But I have no interest in a HRM ;)

    Very true that BF%, or rather, the other side of the equation, LBM%, has an effect on what your metabolism really could be (I put it that way in case someone is suppressing it by not feeding at least that level).

    And with faster metabolism because of more LBM, then more calories burned at all activities.

    So as my thread on the Polar HRM setup for BMR suggests, Polar is doing a BMR calc with your stats and then uses that in a calorie burn calc.
    But their BMR calc, like MFP Mifflin formula, or the ever popular Harris formula, does not take into account a more accurate BMR estimate using BF% - Katch McArdle.

    So the studies that the BMR calcs come from are first off based on participants at healthy weight already. And second have avg LBM/BF percentage for healthy weight, I forget the ranges, but where you expect to see avg healthy ranges quoted.

    So Mifflin and Harris BMR calc usually over-estimates BMR for obese people that have a higher percentage of fat than the study had. That means less LBM, that means really a smaller BMR.

    That's one of the reasons it is said obese can go below their BMR safely without as many problems. True if just a little below, because their real BMR is indeed lower. Not true if they calc'd BMR by Katch method.

    But the Katch BMR calc usually underestimates for obese, because fat does take energy to support by BMR, but only LBM is included in the formula.

    So you couldn't really workout from machines what that might be. First they aren't even taking the bigger influence of calorie burn into consideration - HR.
    You doing pace with HR at 160 will burn decently more calories than same pace at HR 130. And treadmill just doesn't know that.

    You would have to find out what was the average bodyfat% of the folks that was used to create those tables/formulas for exercise calories. Because they only use weight, I've never seen age or gender. Some machines at least do that. Some of their manual may also suggest what avg HR they are expecting someone to do.

    I really think your variance of error based on age, gender, and HR, is going to far over-shadow the difference in LBM between you and the control group.
  • heybales
    heybales Posts: 18,842 Member
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    With my actual information, it tells me that my "Harris-Benedict Formula" BMR is 2087. This is the one that uses age, but not body fat composition. With my actual information, my "Katch-McArdle Formula" BMR is 2108. This is the one that uses BF% but not age.

    So I go back and reduce my age by three years and Harris-Benedict is 2107 and Katch-McArdle is still 2108. So if I'm understanding all this correct, I'm 51 but I have the body fat percentage typical of a 48 year-old. Woohoo!

    Keep working out and that range will change even more!

    Then you can have the body of an avg 30 yr old - woohoo! Actually, they use the BF% stat, but Katch calculates on LBM. So you have the LBM of your avg 48 yr old.

    I try to think positive like that anyway. For instance, my measured max HR is the same as a 26 yr old according to the ever generic 220-age formula.

    And for this method, not nearly as impressive, avg LBM of a 38.5 yr old. So 5 yrs younger. I'm just glad it's not my 5 yrs younger self, that would not be good. LOL.

    How come my back feels like the back of a 55 yr old though!
  • heybales
    heybales Posts: 18,842 Member
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    That post is all sorts of wacky. I wasn't far off on what I thought my bf% was, but apparently it means I have to go 8 years older to get the same bmr needs. Which seems...odd. Right? Do older people have naturally lesser bf%?

    It means you have the Lean Body Mass of an average lady your weight/height but 8 yrs older.

    That's why I joked everyone would hope to get younger.

    What it means is, at far as the Polar knows, you are being given an estimated calorie burn higher than you are really burning, because you have less LBM, therefore slower metabolism, then they are estimating you have.

    But 8 yrs is nothing! Keep doing weight lifting, lose some more fat, and your LBM for weight/height will be right on, or even better! So younger.

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