HRM experiment re: BMR

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themyriadthings
themyriadthings Posts: 225 Member
in Health and Weight Loss
So I decided to use my heart rate monitor to try an experiment: I put it on and laid down on my bed, waited for my heart rate to go down to its base rate (68-70ish) and pressed start. I laid there for exactly 10 minutes and pressed stop. I had burned 15 calories, or 1.5 calories per minute. With 1440 minutes in a day, that means I burn 2160 calories just laying around doing nothing, which is my Basal Metabolic rate, right? But when I check the BMR calculator here on MFP, it shows I burn 1288 calories per day. I know that the BMR is just an estimator, but wow, that's quite the difference. Has anyone else tried this using their Heart Rate Monitor? And what does this mean for my calorie intake? I eat about 1200 cals per day plus about 1/2 or 3/4 of my exercise calories back, for about a total of 1400 per day. Does this mean I can eat more, or should I not mess with that, since following MFP to the letter is what has helped me lose 35 lbs so far?

I'm interested in what others have to say on this topic.

Thanks :)

Replies

  • MariaAlexandra
    MariaAlexandra Posts: 126 Member
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    That's interesting! I also have a heart rate monitor watch with a calorie counter, I should try that experiment.

    The only thing I see wrong with experimenting is that you might have this in your mind, that maybe MFP is not accurate and all that, just keep doing what you're doing : )
  • themyriadthings
    themyriadthings Posts: 225 Member
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    In some ways I regret trying this experiment, because now I think I have more of a calorie deficit than I might really have! The reason I did it is because I thought that the HRM would be the most accurate way to measure calories burned under any circumstances, but maybe that's wrong?
  • potluck965
    potluck965 Posts: 529 Member
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    I think you would have to actually lay around in bed and not move for 24 hours to get an accurate comparison for your BMR. At least try monitoring 12 hours at rest if possible.

    I'just got my HRM today and am having fun with it. I plan on doing a 24 hour monitor just to see where my lifestyle really fits in with the choices you have here when you first input your info.
  • ginnyroxx
    ginnyroxx Posts: 763
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    I think you would have to actually lay around in bed and not move for 24 hours to get an accurate comparison for your BMR. At least try monitoring 12 hours at rest if possible.

    I'just got my HRM today and am having fun with it. I plan on doing a 24 hour monitor just to see where my lifestyle really fits in with the choices you have here when you first input your info.
    I don't think HRM's are accurate when used for extensive periods of time. The Body Bugg works for this, though.
  • themyriadthings
    themyriadthings Posts: 225 Member
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    That is a good idea. I think I will put it on before bed tonight and wear it while I'm sleeping and then for an equivalent amount of hours while I'm awake just doing normal stuff.

    Edited to add: How come HRMs aren't accurate over long periods? Do they not work well when heart rates go below a certain threshold maybe?
  • roadtoaddmj
    roadtoaddmj Posts: 9
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    I had some questions regarding my HRM's calorie burn calculations and I have found that others on the web think that Polar's calculation is about 30% on the high side.

    Tracking my exercise, calorie's and weight loss I have to agree with the +30%.

    If you then mix in some strength training you lose the ability to track with any accuracy at all.

    You should be taking your resting HR first thing in the morning before do anything.
  • Craig772
    Craig772 Posts: 100 Member
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    My HR can drop to around 45 if I concentrate or really relax. Assuming yours did the same when you're actually asleep then it might reduce the 872 calorie differential between your 2160 projected by the HRM and the estimated of 1288. Not by much though?
  • themyriadthings
    themyriadthings Posts: 225 Member
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    I should definitely check it in the morning before assuming anything, and maybe even wear it all night. I will try both and see what happens! Either way, I'm not going to start increasing my calorie intake - what I'm doing is working so there's no sense messing with it!

    Thanks for the feedback and suggestions everyone. Wishing you all health, happiness and contentment. :)
  • binary_jester
    binary_jester Posts: 3,311 Member
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    This might help...
    http://www.myfitnesspal.com/topics/show/137338-how-one-brand-of-hrm-calculates-calories
  • millerll
    millerll Posts: 873 Member
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    No, no, no!!! This is totally incorrect! HRMs are NOT accurate for measuring calories burned while not exercising. The science behind why is a little complicated for me to explain with my limited knowledge, but one of our fellow members, Azdak, has made at least one post about it. Please do a search for his articles about this. The calorie numbers you're getting from a HRM while doing nothing are useless. Your actual heart rate should be accurate, but not much else. If you want to know your daily calorie burn, get a Bodybug. They're designed for this use. Until then, stick with MFP's BMR estimate. I've found it to be pretty accurate. Good luck!
  • Stewie316
    Stewie316 Posts: 266 Member
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    I wouldn't trust the HRM on anything but aerobic exercise. It's not designed to give you a daily calorie burn. I can't explain it as good as some of the other people here, but here's two good article's about it.


    http://www.sparkpeople.com/community/ask_the_experts.asp?q=75

    http://www.ehow.com/how-does_5700177_heart-monitors-calculate-calories-burned.html#ixzz13xTqD6FG


    If you really want a more accurate daily calorie burn, I would suggest getting a BodyBugg or BodyMedia. It's designed for all activity.
  • pamelasusan
    pamelasusan Posts: 90 Member
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    I have a Go Fit Wear (Body Bugg for 24 hour use).......I can't rave enough about it.

    On sale this weekend 25% off with free shipping. Awesome deal if you are going to be monitoring for a long time.

    I love mine and wear it all the time except for showering.
  • themyriadthings
    themyriadthings Posts: 225 Member
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    Lots of good information - thanks! I had a feeling the HRM numbers just couldn't be right!
  • slieber
    slieber Posts: 765 Member
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    If I wore my HRM all night long I'd burn a load of calories - I can't stay still when I'm sleeping!

    Is it worth getting a body bugg and using it instead of the HRM if one does weights, dance, etc. in addition to aerobics? I just laid out money for a Polar FT40 to replace the F6 that died. I want to know if I made a good choice.
  • JLeeAlton
    JLeeAlton Posts: 311
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    This is all really interesting. I am considering a body bugg now.. I have my activity for the day set a light.. but honestly I move all day at work. Not walking around but arm movements all day long. I wonder if my activity should be set higher. hmmmmm
  • themyriadthings
    themyriadthings Posts: 225 Member
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    It almost seems worthwhile to have both an HRM and a BodyBugg device....
  • rescuepete
    rescuepete Posts: 58 Member
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    I started using a HRM when I felt like I didn't trust MFP's calculations for my aerobic exercises, but I am ok with their BMR algorithm only because like you it's been pretty so-far-so-good with MFP. I'd just consider the BMR calculation to be the man behind the curtain ala Wizard of Oz, and not bother looking into it too far. I'd hate to spoil it.
  • slieber
    slieber Posts: 765 Member
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    The body bugg is frightfully expensive! I'm not sure it's worth it to have both or even to have just the BB. The HRM gives me instant feedback without me having to visit a computer.
  • Azdak
    Azdak Posts: 8,281 Member
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    You cannot use an HRM to estimate resting calories. I don't have time to go into detail, but you just can't. The calorie estimates are only accurate for steady-state aerobic-type activities that are done at an intensity of at least 40% of VO2 max. Under 100 or so beats/min, heart rate can vary for many reasons other than increased energy expenditure.

    The BMR equation on MFP is fine--it uses one of the more accurate equations out there. I am only a sample of one, but I had a metabolic test done recently that directly measured my BMR -- and it matched the MFP number almost exactly.

    A body bugg device is a more accurate way to estimate resting and everyday activity energy expenditure--I don't think they are very good for exercise.
  • iamstaceywood
    iamstaceywood Posts: 383 Member
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    The BodyBugg is also worn 24 hours.
    I was researching HRMs and they were only 40$ more for the bugg than a decent monitor, not the nicest, just a nice one. I paid 160 for my bugg and I love the thing. I love to know how many cals a min i burn all day long. It makes me happy. I enjoy the data and all the different ways of looking at the reports and such.
    I'd much rather have the bugg than the hrm. I HOwever, am not a hardcore athlete training for something or anything, just a fat girl losing like 14 lbs a month.

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