Accuracy when adding calories.. A point to consider!

acresfield
acresfield Posts: 122 Member
edited December 17 in Fitness and Exercise
I might be wrong and so stand to be corrected!

I was logging my calories burned by using a heart rate monitor and manually entering them into MFP. So let's say I have myself down as semi active and then burn 700 calories in an hour doing a workout., I would enter, and then eat back the 700 calories.
I then bought a fitbit and now enter my calories through that site instead.

Now here is the thing I have realised.... When you enter via the fitbit website, it sends the calories to MFP for my workout, after first of all making a deduction for the amount of calories I would have burned if I had just sat on my *kitten* instead of working out. so for example, it sends over 630 instead of 700. I.e. approx 90%.

I guess that I should have been doing that all along? It's much worse when you consider that usually my workout would be 3 hours or so playing tennis, and average burn would be anywhere from 1000 to 1800 calories, and I would have therefore been eating back upto 200 calories too much following a workout.

When you are trying to find your correct balance this could be quite an issue.

Am I reading too much into this?

Replies

  • juliekaiser1988
    juliekaiser1988 Posts: 604 Member
    I've thought about that before myself. Curious to see responses.
  • kdeaux1959
    kdeaux1959 Posts: 2,675 Member
    I have thought about this before as well.. Therefore, I never eat back all my calories.
  • mfpcopine
    mfpcopine Posts: 3,093 Member
    I have a Fitbit and a heart rate monitor. I happened to see this article on fitness monitors and it reflects my position on them in regard to calories:


    "Decide whether a calorie monitor is essential. Although devices that estimate the number of calories you burn may be appealing, they are often inaccurate unless adjusted closely for your current fitness level, age, and other health indicators.
    Calorie burn monitors may be useful if you have a general idea of the target number of calories you would like to burn at each session, but they should not be considered extremely reliable if factors such as BMI, resting heart rate, and other in-depth indicators are not taken into account in the calculation."


    http://www.wikihow.com/Use-Fitness-Monitors
  • mostaverage
    mostaverage Posts: 202 Member
    I read a thread on this subject recently and you are correct, for accurate calorie burns you need to take the calories burned during a workout and subtract the BMR calories you would burn for the duration of the workout e.g 1hr football=1000cal 1hr BMR=200 cal - entry 800 cal.
    Alternatively, you track the calories on the workout but dont track the cals during the warmup and cooldown, when your heart rate is elevated beyond resting, it's not exact but close enough to compensate.
  • CyberEd312
    CyberEd312 Posts: 3,536 Member
    I use a Polar FT60 for my calories burned (only log cardio calories burned, I never log Strength training calories burned) but I only eat back 85-90% leaving a 10-15% margin for error in calories burned or logging calories.... It has worked just fine for me doing it this way... check out my ticker......... Good Luck to you on your journey.....
  • kateopotato
    kateopotato Posts: 215 Member
    I always do that when using my HRM. I subtract out the number of minutes I worked out X 1.35 (that's the number I was given as my RMR calories burned per minute when I got it done last year)... It definately makes a difference when you have long work outs. It IS all estimates, but that way I feel like I was doing what I could to make it as accurate as possible.
  • spynoodle
    spynoodle Posts: 404
    I use a Polar FT60 for my calories burned (only log cardio calories burned, I never log Strength training calories burned) but I only eat back 85-90% leaving a 10-15% margin for error in calories burned or logging calories.... It has worked just fine for me doing it this way... check out my ticker......... Good Luck to you on your journey.....

    305 pounds?!?! Amazing!!!!! You are a rockstar!!
  • Rae6503
    Rae6503 Posts: 6,294 Member
    But really it's only 70 calories which doesn't make a huge difference in the grand scheme of things, so it's not really worth obsessing about.
  • Cold_Steel
    Cold_Steel Posts: 897 Member
    I think MFP over shoots by about 20-30% so I just make the change myself when the calculator puts it in I just manually change it. I generally only eat half to 3/4 of the calories back. But I have no real plan I just sort of wing it. I like to tell myself I do
  • theNurseNancy
    theNurseNancy Posts: 149
    How is fitbit more accurate? It's nothing more than a glorified fancy pedometer. Sure, it's great for motivating you to be more active during the day, but you shouldn't be logging ALL activity for the day. MFP already takes that into account based on how active you set yourself to be. You should only be logging activity that would count as extra for the day.

    It's not all about how far/fast you're moving, but also how well your heart interprets your activity. If you're fit, you burn calories at a different rate than someone who isn't, regardless of how much you weigh.


    Taking that into consideration, I don't start or end my "workout" on my HRM until it reads 130 to account for BMR.
  • Toddrific
    Toddrific Posts: 1,114 Member
    I'm going to say all this calorie counting has a margin of error. Just assume that error exists and roll with it.
    Even if you are weighing every ounce of food, there is variance in what you eat too.

    If you are losing weight with Method A, no reason to overly worry about it.
  • girlnumber57
    girlnumber57 Posts: 72
    I have my profile set as completely inactive. This way when I burn an extra 300 or so calories a day moving around cleaning house or whatever, it gives me the extra room to not worry about this issue. I can then eat all of my exercise calories back from my HRM reading.
  • o_delaisse
    o_delaisse Posts: 193 Member
    Now here is the thing I have realised.... When you enter via the fitbit website, it sends the calories to MFP for my workout, after first of all making a deduction for the amount of calories I would have burned if I had just sat on my *kitten* instead of working out. so for example, it sends over 630 instead of 700. I.e. approx 90%.

    I never even considered that.... Thank you for sharing :)
  • mamato2babes
    mamato2babes Posts: 90
    I was just getting ready to ask this very same thing! Just got a Polar FT4 HRM yesterday and went for my first run with it today. I went ahead and logged the calories it said I burned, but I did wonder if I should subtract what I would have burned for that hour just sitting around?? Very confusing.
  • vjrose
    vjrose Posts: 809 Member
    After considerable reading on HRM's I always subtract around 15% before logging it to allow for that very margin of error and redo my weight in the monitor regularly.
  • acresfield
    acresfield Posts: 122 Member
    Thanks for responding everybody. I didn't really intend it to sound obsessional and I always slightly undercount but when you are working with margins then I guess every little helps. Particularly until I find my 'balance'

    I don't think that fitbit is more accurate than a HRM, the question was more about logging calories from whatever method you use and whether they should all be counted or not? How much of an adjustment does MFP make?

    Some great ideas in the answers though.. I like the idea of reducing activity level (perhaps not to completely inactive) in order to give me a buffer for inaccuracies

    Thanks again

    Ian
  • basschick
    basschick Posts: 3,502 Member
    Yes, I always subtract the number of calories I would have burned anyway. So for instance, this morning my HRM said I burned 340 calories during a 55 minute Zumba class. I subtracted 51 from that number and logged 289 on MFP. Before I started doing this, I was slowly gaining weight and couldn't figure out why when I was supposedly under my calorie goal. When I started subtracting calories, I started losing a pound a week.
  • acresfield
    acresfield Posts: 122 Member
    I use a Polar FT60 for my calories burned (only log cardio calories burned, I never log Strength training calories burned) but I only eat back 85-90% leaving a 10-15% margin for error in calories burned or logging calories.... It has worked just fine for me doing it this way... check out my ticker......... Good Luck to you on your journey.....

    Fantastic stats.. Well done!
  • mamato2babes
    mamato2babes Posts: 90
    Yes, I always subtract the number of calories I would have burned anyway. So for instance, this morning my HRM said I burned 340 calories during a 55 minute Zumba class. I subtracted 51 from that number and logged 289 on MFP. Before I started doing this, I was slowly gaining weight and couldn't figure out why when I was supposedly under my calorie goal. When I started subtracting calories, I started losing a pound a week.

    How did you know to subtract the "51" calories? Is there a formula out there to figure this number?
  • rileysowner
    rileysowner Posts: 8,336 Member
    Few of my workouts go even to an hour. Most are 40-45 minutes, so I don't really worry about it. If I workout for a very long period of time, say when I go on a 30 mile bike ride, I might consider it, but even then I usually don't. For me at this point it is a moot point since I don't use MFP's calorie calculations any longer. I calculate my TDEE including exercise, and then take off 20%. I eat those calories, and don't add anything for burned calories. Since I am very consistent with exercise, this approach works better for me. If I became less regimented with my exercise, or started skipping workouts, I would go back to MFP's approach. If I had one of those days where I have a huge burn, say the 30 mile bike ride, I would likely eat a bit more because that would be above my normal exercise, but even then, I wouldn't obsess about getting them all eaten.

    Having said that, for those who workout an hour or more, this is a wise thing to do. Just take your BMR, divide by 24, multiply that number by the hours of your workout and subtract that from your burn.
  • Azdak
    Azdak Posts: 8,281 Member
    Whatever method you choose to track calories, the fact is that NONE of them are accurate enough to worry about 10% or even 20% variances. If you are tracking calories so closely and obsessing about 100 calorie difference in a day, IMO you are expecting a level of precision that is impossible.
  • nikkijoshua
    nikkijoshua Posts: 85 Member
    But really it's only 70 calories which doesn't make a huge difference in the grand scheme of things, so it's not really worth obsessing about.

    I agree. Also, after a workout, your metabolism is elevated, so depending on what type of workout you've done, you'll be burning more calories per hour for the next hour or more than you would if you hadn't exercised so I figure it all balances out. The increase in the amount of calories you burn because of exercise don't stop once your workout has stopped. The more intense the workout, the more calories you burn per hour after the workout even when you're at rest. If you do nothing but sit for the next hour after an intense workout, you'll burn more calories just sitting after that workout than you would just sitting if you hadn't exercised. So if you neglect to subtract your BMR calories from your HRM reading, you are likely to to burn up those calories following your workout anyway. All of these devices are really good estimates of the amount of calories you've burned, but nothing is exact, so I don't get too technical with it.
  • kyle4jem
    kyle4jem Posts: 1,400 Member
    When I first started using my HRM I never thought about the fact that just being alive burns calories and the HRM cannot distinguish between BMR and exercise calories. Then I saw some great posts on the MFP message boards and learnt the error of my ways.

    I've also used my HRM at rest, so I know roughly what my BMR is and more importantly, I've worn it for a few hours while working, so it calculated my sedentary TDEE and that's the figure I use to deduct from my HRM- or MFP-exercise calories.

    Even then, I still only eat back about 50-70% of those over the course of the week.

    It seems to be working for me, so I don't see any reason to change things at the moment :happy:
  • acresfield
    acresfield Posts: 122 Member
    Whatever method you choose to track calories, the fact is that NONE of them are accurate enough to worry about 10% or even 20% variances. If you are tracking calories so closely and obsessing about 100 calorie difference in a day, IMO you are expecting a level of precision that is impossible.


    I'm an engineer.. Can't help it!

    However, it's not about obsessing over 100 calories, it's about gaining an understanding of all of the forces at work!
    People give up with diets because the things they expect to happen fail to materialise.. At least that's what I did in the past.
  • deetra
    deetra Posts: 35 Member
    Everyone has their own opinions on this but to me if you work out and then eat back the calories its almost the same as if you didnt work out !! Say your maintenance caloriese are 1200 a day so then you work out and it says you have gained 600 back, if you eat them then to me it defeats the purpose, u would be better off now to work out and just stick to 1200 daily !! This is why i always enter my work outs and exercise AFTER i have entered my calories as then there is no way i will eat back my calories !!
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