Calories burned are incorrect - too low for some activities

[porcelina]

HI all,

I am a new member and looking for some help.

I have been tracking and logging fitness and food for many years now via sparkpeople.com. I also used to use a polar hrm for tracking calories burned when I was initially losing weight around 4-5 years ago. Neither of these had the same level of detail as the fitbit, and so I am still getting used to everything and figuring out how it all works. However, I am getting a bit perplexed!

At my goal weight (139 lbs) according to my HRM, I was burning about 400 cals on a 30 minute run and around 600 for an hours high intensity circuits class, sometimes 700 for Body Attack. Spark people would give a lower cal burn because it was more of an estimation than an accurate reading. 

I have been using my fitbit charge hr now for around a week - I have worn it for a 32 minute run, during a 45 minute Body Attack class and then for GRIT strength and CX worx this morning. Each of my burns seems a little low in my opinion: 169 for GRIT, 341 for my run, 356 for Body Attack.

The run probably makes sense to me as it was a gentle run as I am getting over a chest infection, however the gym classes don't. I don't wish to blow my own trumpet or sound conceited but I worked really hard - and always do - in GRIT and Attack. Also, a lot of my friends have fitbits and their burn was a lot higher than mine, and we were all pushing equally as hard together!

I am wondering if I have something set up wrong, or if I am using it incorrectly? The polar unfortunately is broken and it was a couple of years ago when I was using it, so it could be that over the years my body has gotten used to working at high intensity during these activities and so I don't burn as much - however I still feel just as pooped at the end of the sessions as I used to do!! Maybe I need to find some more intense workouts!

Any help would be gratefully received. Thank you.  

[Mike007]

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@Julia_G wrote:

Hi, @Mike007, no, I did mean losing weight.  If the Fitbit is UNDER counting calories, and you are actually burning much more calories than the Fitbit thinks, you might find yourself losing weight... (assuming, of course, you eat based on the information Fitbit gives you).

If you don't find yourself losing weight by using the lower calorie burn calculations, that would suggest the lower burn is correct.

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Sorry, I get what you're saying now. I'm one of the majority that use the Fitbit to lose weight so what you first said didn't make sense 🙂

[Julia_G]

@Mike007, I think that is all the more reason to take the conservative (lower) calorie estimate.  As I mentioned above, I believe most people very much over estimate how many calories they burn from exercise.  

[Mike007]

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@Julia_G wrote:

Most people, and aparently many systems, vastly over calculate calories burned from exercise.  I think Fitbit is correct.  Unless you are following Fitbit's systems and actually losing weight, I would go with them.

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I agree with you, it was your use of the word "unless" that confused me. 

[liesbethj]

No, they will be exactly the same. It will cost a strong elderly woman just as many calories to do exactly the same exercise as a a young weak man. He will have less muscle power and be more tired afterwards, but they will have used the same amount of calories. 

[Mike007]

@liesbethj not even close.

[liesbethj]

can you then explain how, if lifting a weight cost a certain amount of energy (and that energy can be calculated exactly by applying physics and it can be meassured in calories) , how can it take one person more energy (meassured in calories) than another person to lift that weight?

[Julia_G]

Because the calories expended in any activity are also related to your own body and bodily processes.  You aren't just lifting a weight, you are firing your own muscles, lifting your arm(s), keeping your heart pumping and your lungs expanding etc.

Most of the calories you burn will be your bodily calories, and that will differ, of course, depending on your gender, age, weight etc.

[Mike007]

Many things affect calories burned. Age, weight, fitness level, muscle mass.....

Edit- thanks @Julia_G 😄

[liesbethj]

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Most of the calories you burn will be your bodily calories, and that will differ, of course, depending on your gender, age, weight etc. 

that is what I am not so sure about. I agree there is a difference in metabolic rate for people. In rest and apparently during an activity, but is this difference in calories per minute  really relevant? (this is for working at a fitness machine, when the weight lifted or moved is not the weight of the person lifting it)

[Mike007]

I give up!

[Goldilocks81]

I give up as well.  Between the FB Charge 2 not being able to keep up with steps during high intensity/speed runs and the calories being way off I just have a cool watch that tells me if I've sat on my duff all day or not.  For example yesterday I worked out for 90 minutes and had over 12k steps and 1200 calories burned. At the same time today I've been much calmer and inactive with just over 4k steps and yet just over 1000 calories burned.  That's just impossible.  There's no way someone works out for 90 minutes and the difference is 200 calories.  (In total yesterday I had reached slightly more than 2200 calories burned for the day.)

[calrenbowie]

Actually that sounds about right.  I weigh 129 and if I dont do anything but sit on the computer all day I will burn 50 calories an hour.  So with the added intensity of one 90 minute workout at 125 extra calories (your body is normally burning 75 just to survive) that would equal the difference.

Carlen Bowie

Fitness Instructor
Y of Central Maryland
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[calrenbowie]

Actually that sounds about right.  I weigh 129 and if I don't do anything but sit on the computer all day I will burn 50 calories an hour.  So with the added intensity of one 90 minute workout at 125 extra calories (your body is normally burning 75 just to survive) that would equal the difference.

However, if you weigh more than I do you will burn more than I do.  Same is true if you weigh less you will burn less than I do doing the exact same exercise. Also people in great athletic shape - it takes more for them to burn calories because they need to get the heart rate up.

[calrenbowie]

This may help with knowing how many calories you burn in a resting state - 

How many Calories do I Burn doing Nothing? 
Here’s the formula to find your resting metabolic rate:

For Women: BMR = 65 + (4.35 x weight in pounds) + (4.7 x height in inches) - (4.7 x age in years)
For Men: BMR = 66 + (6.23 x weight in pounds) + (12.7 x height in inches) - (6.8 x age in years)

Another lazier way to get a (very rough) estimate is to multiply your body weight in lbs by 11.

By now know that weight maintenance or loss is a matter of energy burned versus energy consumed, and it's clear that exercise can significantly increase the food that we can eat each day without putting on extra weight.

Here is part of the reason why I think many of us are overweight; it's very easy to do nothing (or close to it) without even realizing it, and we very rarely are conscious enough of our activity levels to adjust our diets to reflect the small number of calories we are burning.

[Goldilocks81]

There's absolutely no way I can work out for 90 minutes, hard, and burn
200 extra calories compared to a day where I've taken it easy. In fact,
now that my day is over I still have "zero active minutes" and I've burned
more calories than I did yesterday and tracked over 4 miles less today. 4
miles less and yet more calories burned. Sorry, but Fitbit's math is just
not adding up.

[Mike007]

If you have a tracker that measures HR then of course you can burn more calories in a day that you've done less steps, you could be doing something that raises your HR whilst doing no steps at all.

[calrenbowie]

Goldilocks81 - If you are unsure, ask to borrow a heart rate monitor at the gym and track it with your fitbit.  I did that and it was spot on.  If your fitbit doesnt have a HR monitor it  cant accurately track your calories.

[Looby52]

I used the link to work out my maintenance calories and it says 2007 calories. I'm eating 1300 or less per day but my Fitbit charge 2 is saying I am only burning around 1140 calories a day. This seems a bit low considering I walk my dogs most days for an hour and do over 5000 steps. Seems a bit low? 

[Looby52]

I think the company needs to address these problems with accurate tracking. People are paying good money for these trackers (I paid £120 for Fitbit charge 2) so I expect it to deliver what they say it delivers otherwise it's not fit for purpose and should be sent back for a refund

[Veryberrystyle]

I do a minimum of 20000 steps a day with a very active job and run 10km each day and I rarely reach 2000 calories each day.