HRM vs MFP Accuracy question...

spingirl605
spingirl605 Posts: 181 Member
in Health and Weight Loss
I see a lot people saying that MFP can over exaggerate calories burned during a workout. I use a HRM when I work out, and my calories burned are always way more than what MFP shows. For example, I spin for about 50 minutes twice a week. My HRM last Tuesday said I burned 575 calories, but when I input it into MFP for 60 minutes, it only comes up to 437. How accurate is a HRM??? I have "Sports Tracker" on my phone, and bought the chest strap to go with it. I've also used a Polar watch with a chest strap, and they are pretty close to one another as far as results go. I think my sports tracker may give me a few extra calories burned...

Replies

  • MscGray
    MscGray Posts: 304 Member
    Just checking....did you make sure that your physical profile matches on all of the equipment that you are comparing? if your weight is heavier in one then the other that could easily skew the results. Also are you stopping the HRM as soon as the work out is completed? I had a tendency of forgetting to stop mine so it would continue to log the drive home and what ever else I did before changing out of exercise clothes and catching my slip up. Plus take into account intensity...I always pick the lowest of intensity if I use MFP database...when really I could be pushing moderate or high....other then that I am fresh out of ideas...hope you figure it out :smiley:
  • spingirl605
    spingirl605 Posts: 181 Member
    Thanks MscGray!!
    I do stop it right away after my workout because I like to let the class know approximately how many calories were burned in a work out. I know that my calories burned will not be the same as someone next to me, but I like to give them a general idea. I don't use machines, so it's only my sport tracker or MFP that I go by...I'm just more curious if a HRM is the best way to determine calories burned, or if there are other more accurate methods...Thanks for the advice though on maybe I'm not logging the right "intensity"!! That might make sense...
  • Hornsby
    Hornsby Posts: 10,322 Member
    Keep in mind that HRMs usually don't adjust for the calories you would have burned if you were just sitting. It only shows the gross burn as opposed to net. If you have a BMR of say 1500, you would need to subtract those calories from the number the HRM is giving you. So 1500/24=62.5. If you subtract that from the 575 it gives you around 507 which is closer to MFP. Either way, all calorie burns are estimations and require some level of "experimentation" to determine what you are actually burning.

    In this instance, I would mark it down as 500 and go about my day as usual.
  • SLLRunner
    SLLRunner Posts: 12,942 Member
    Spingirl605,

    I have a Polar FT7 and it always comes out less than MFP and the gym machines. For example, I ran 4 miles at 6.0 mph this morning and my heart rate monitor rendered 318 calories. MFP gives 422 and the treadmill give about 500 or more. However, my phone app would give less calorie that my heart rate monitor.

    Based on the fact that I've been using a heart rate monitor for cardio for most of my weight loss journey, and I've been in maintenance for almost a year and still use it, I would say my heart rate monitor is the most accurate of all the sources I mentioned.

    What about you? How long have you been using the heart rate monitor? What is your weight doing?

    I think it's all about trial and error.
  • ThatGirl_1968
    ThatGirl_1968 Posts: 47 Member
    I have the same concerns with my Polar HRM and have stalled in weight loss even though I've been exercising regularly. I've now started to eat back a portion (or sometimes none) of the exercise calories to see if that adjustment will help. I do think there's an intensity difference for me in my workouts compared to MFP because I often do intervals of hills/speed rather than a steady rate of speed at the same intensity for the given period of time and I think intervals will burn more calories - ditto a zumba class. Of course I'm no expert and am just adjusting the amount of calories I eat vs the exercise output based on the HRM until something works. Good Luck
  • spingirl605
    spingirl605 Posts: 181 Member
    I've been using a HRM off and on for about a year, but I need to get more focused on this weight loss thing. I've been on MFP for about 5 months now and I have not lost one pound...Not 1. So I'm trying to kick it up a notch. More diligent about logging accurately I guess is my plan. So I think I'll keep using it, and see what happens when I start being more "truthful" in my logs...Thanks ladies!!
  • MscGray
    MscGray Posts: 304 Member
    I agree w/ keepingsecret. I would likely trust my polar results over anything else. Don't give up...keep on fighting and make minor adjustments here and there....its all about trial and error!
  • TimothyFish
    TimothyFish Posts: 4,925 Member
    Both the number in MFP and the one from a HRM are estimates based on what was observed for other people. Don't expect either to be 100% accurate. Also, as someone mentioned above, the MFP calories burned and the HRM caloried burned don't subtract the calories you would've burned doing nothing. (That only matters if you are trying to figure out how much to eat.) If you are in a low oxygen environment or you're body's cooling system is having trouble keeping up, your heart rate will be elevated and give a higher reading. On the other hand, in cool weather, your heart rate may slow down and you'll have a lower reading, even though you are performing the same amount of work.

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