Burning less calories?

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  • sijomial
    sijomial Posts: 19,809 Member
    @nytrifisoul

    Warm yourself up first on the exercise first.
    Reset the bike and your HRM.

    Then do 60mins at 222 watts average output and you will have burned almost exactly 800 net cals in that hour. Good luck, it's an achievable goal for many male cyclists - a good club rider pushing hard could well be around that number.


    I managed to calibrate a Polar FT60 HRM against a power meter over several training sessions and got them reasonably close for steady state rides (close enough to be a perfectly usable estimate).
    But for interval training that same calibration fell apart and the HRM over-estimated by about 25%.
    If I over-heated then again its estimates diverged sharply but to a smaller degree.
  • nytrifisoul
    nytrifisoul Posts: 499 Member
    edited November 2019
    Ok this is making more sense to me. I burn roughly 700 cals an hour (at least thats what the bike says) on the exercise bike between 5-6 MET (intensity level) the watts are around 115 - 130 Avg MPH is 20.
  • sijomial
    sijomial Posts: 19,809 Member
    edited November 2019
    nytrifisoul wrote: »
    Ok this is making more sense to me. I burn roughly 700 cals an hour (at least thats what the bike says) on the exercise bike between 5-6 MET (intensity level) the watts are around 115 - 130 Avg MPH is 20.

    130 watt average cycling for an hour = 468cals. There's a very well known relationship between cycling power and net cals.

    Ignore "speed" indoors as it bears no relationship to real speed achieved outdoors.
    (A 130 watt outdoor ride for me would most likely be a gentle spin with a speed range of 12-14mph.)
  • NorthCascades
    NorthCascades Posts: 10,968 Member
    nytrifisoul wrote: »
    Ok this is making more sense to me. I burn roughly 700 cals an hour (at least thats what the bike says) on the exercise bike between 5-6 MET (intensity level) the watts are around 115 - 130 Avg MPH is 20.

    Everybody has almost the same efficiency for turning calories into watts on a bike. Lance Armstrong and Rosanne Barr are only 5% apart. That's not my personal opinion that's hundreds of research studies, many done in metabolic wards. Bikes are a special case, you sit down, you turn your feet in circles that are always the same size. It's not like running where you can waste energy bouncing up and down too high or have some other form of efficiency ("running economy") difference.

    138 watts is just a hair below 500 kCals per hour. With a maximum error of +/- 2.5%.

    It doesn't matter what speed, it matters how many watts. I can burn more energy going 5 mph up a hill than 20 mph down one. Watts are basically a measure of the energy you're putting into the bike. (Technically they're a measure of the rate you're doing physical work.)
  • NorthCascades
    NorthCascades Posts: 10,968 Member
    Azdak wrote: »
    nytrifisoul wrote: »
    Azdak wrote: »


    Look at my previous post. Your average calorie burn is probably about 1/2 of what you are estimating.

    The fact that you are using inflated exercise numbers and yet still losing weight just points out the inherent inaccuracies of trying to estimate calorie intake, exercise calories, and “movement” calories.


    If that was the case, i would be gaining weight, or if i was lucky, just maintaining. I am definitely eating back more then 1/2 of what i am exercising.

    There is more to the equation than exercise calories. When I initially lost 60 pounds, I looked back and calculated my average deficit. I had structured 1000 cals/day, but it worked out to 1875 per day for five months. Depending on how you count it, NEAT calories can make quite a difference.

    But physiologically, you would have to be working at 9-10 METs to burn the calories you claim during your workouts. That is not impossible, but I could find no literature for the TC 100 at the speeds you say you are using that would support such a number. The reported numbers are 4-5 METs which would give the calorie numbers I referenced earlier.

    You are making progress and happy with your choices, so I don’t want to belabor what is a more of an academic argument. But this is my area of expertise and so I like to make sure that others who read these comments have realistic expectations.

    To end on a positive note, I do agree with your original comment that it is quite possible for an average someone weighing above 80kg and of above average fitness level to burn 700-800 calories per hour during exercise. You don’t have to be an elite athlete.

    For what it's worth. I'm a motivated recreational athlete, for sure not elite level. About 100 kg. Before my accident my FTP was about 275w, which is 990 kCal in an hour. That's the most I'm capable of, with extreme motivation, and takes a few days to recover from. I basically have to limp home whimpering the whole way after that. This is on a road bike and the kCal number will probably be different with other modalities.

    TL;DR you're right.
  • KDBisme
    KDBisme Posts: 49 Member
    This is really encouraging for me!! I’ve been so frustrated that other people say they burned 600 calories in a class that I have also done... and I only burn 400?? I wondered how that could be possible when I’m going all out and keeping my hr 160-180... and as far as I can tell working just as hard if not harder. The difference in body weight and fitness trackers makes a lot of sense.
  • naomi8888
    naomi8888 Posts: 519 Member
    NorthCascades wrote: »
    nytrifisoul wrote: »
    Ok this is making more sense to me. I burn roughly 700 cals an hour (at least thats what the bike says) on the exercise bike between 5-6 MET (intensity level) the watts are around 115 - 130 Avg MPH is 20.

    Everybody has almost the same efficiency for turning calories into watts on a bike. Lance Armstrong and Rosanne Barr are only 5% apart. That's not my personal opinion that's hundreds of research studies, many done in metabolic wards. Bikes are a special case, you sit down, you turn your feet in circles that are always the same size. It's not like running where you can waste energy bouncing up and down too high or have some other form of efficiency ("running economy") difference.

    138 watts is just a hair below 500 kCals per hour. With a maximum error of +/- 2.5%.

    It doesn't matter what speed, it matters how many watts. I can burn more energy going 5 mph up a hill than 20 mph down one. Watts are basically a measure of the energy you're putting into the bike. (Technically they're a measure of the rate you're doing physical work.)

    I love this info. I used to track burns by HR and was way off until @sijomial got me onto measuring watts. It's totally changed my workouts by motivating me to keep over a certain number and turns out I was actually burning more calories than my Apple Watch suggested.
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