Calorie Burning Accuracy

bosox2004
bosox2004 Posts: 8 Member
in Fitness and Exercise
I get on my stationary bike, warm up for a few minutes, peddle through 2 half hour programs and pile up over 18 miles.
According to the bike, Ihave burned 500 calories. In Myfitnesspal, 75 minutes of biking equals something like 1,566 calories burned. I use the bike number. Any comments on the accuracy of either the bike or Myfitnesspal? I believe if i used the 1,566 calories, and actually ate them, I would be gaining weight.

Replies

  • Tedebearduff
    Tedebearduff Posts: 1,155 Member
    Just follow one of them, I'd say the bike honestly because MFP can't gauge your effort level in minutes.
  • pondee629
    pondee629 Posts: 2,469 Member
    Go with the lower calorie burn, If you find it makes you uncomfortable, or you're losing weight too fast, adjust.
  • cmriverside
    cmriverside Posts: 34,412 Member
    Yeah, what they said ^^

    It's always a guess. I just use a flat number every time I exercise based on my many years of logging food and exercise. It's a bit of a science experiment and you're the scientist.

    500 sounds a lot closer than 1500.
  • BrianSharpe
    BrianSharpe Posts: 9,248 Member
    I'd be inclined to go with the lower number too.

    I installed a power meter on my bike last year and it was a real eye opener, based on wattage the calorie estimate that my Garmin gave me for my bike commute was effectively cut in half - about 17 cal per km. 18 miles is approx 29km at 17 cal per km is 489 cal......so the 500 doesn't sound out of line.
  • NorthCascades
    NorthCascades Posts: 10,968 Member
    500 food calories in an hour means 138 watts, which is a good, reasonable effort level for an average person.
  • sijomial
    sijomial Posts: 19,809 Member
    edited July 2018
    500 sounds reasonable, 1,566 in an hour would indicate you could be a professional rider.

    Do remember that stationary bikes don't move so "miles" is irrelevant apart from a comparison with your last session.

    Does your bike give you average power in watts? That's the best way to estimate calories.
    138 watts average for the hour as stated above would be 497 net calories (av watts per hour x 3.6).
  • Themajez
    Themajez Posts: 61 Member
    A side question about Watts. If exercise equipment gives a display of Watts is that purely mechanical energy or is it multiplied by a value to give a typical energy used in the body? I vaguely recall that the body is about 30% efficient for converting chemical to mechanical energy.
  • sijomial
    sijomial Posts: 19,809 Member
    Themajez wrote: »
    A side question about Watts. If exercise equipment gives a display of Watts is that purely mechanical energy or is it multiplied by a value to give a typical energy used in the body? I vaguely recall that the body is about 30% efficient for converting chemical to mechanical energy.

    @Themajez

    The equation given is actually a simplified down version of a much longer formula which includes an estimated efficiency ratio that is for cycling only.
    Cyclists don't actually vary that much in their efficiency, it's a fairly narrow band (about 20 - 25%) and assuming 24% simplifies the maths a lot.
    For more info see http://mccraw.co.uk/powertap-meter-convert-watts-calories-burned/

    You can't use the same equation for other cardio equipment as they will have different efficiency ratios. Rowing is different (Concept2 web site has a calorie estimator), treadmill is different again (use a running formula), elliptical is different again and also very different between different ellipticals as there are many designs and motions.
  • NorthCascades
    NorthCascades Posts: 10,968 Member
    Themajez wrote: »
    A side question about Watts. If exercise equipment gives a display of Watts is that purely mechanical energy or is it multiplied by a value to give a typical energy used in the body? I vaguely recall that the body is about 30% efficient for converting chemical to mechanical energy.

    Mechanical energy. (1 watt = 1 Joule per second). Some bikes measure "immediate" at the pedals, others measure all the way downstream at the wheel and read lower because of drivetrain loss.

    The reason people use watts is that they're an objective measure of effort, which makes them especially great for intervals. The calorie thing is just a happy coincidence.

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