Fitbit calories burned - is this generally accurate?

abbietaylor1

Hey, so I am fairly new to using Fitbit and I just used my Fitbit surge to track my first run. I ran a slow 6.3k (in 42 minutes) and it told me that I burned 643 calories! This seems high to me and so I just wondered what your views were on this? Thanks for your thoughts!

Yi5hedr3

Cut it in half.

Lizzy622

A recent University study had participants wear 12 different trackers and had them in sealed rooms so they could measure calorie burn. Most trackers actually underestimated calorie burn. I basically use mine to track activity and to make sure I keep up a certain level. I don't count on accurate calorie burns.

janejellyroll

I have been using mine since July and find it to be accurate. I've seen that some people report the same, while others think theirs aren't accurate.

robingmurphy

My FitBit is very accurate for me. However, your number does seem high if it were for me. If you are heavier, though, it could be accurate. I weigh 140lbs and burn about 90 calories a mile jogging (that would be 90 calories every 1.61k) so I'd have burned more like 350 calories on your run. However, if you weigh quite a bit more, that could be accurate for you.

zyxst

I find mine to be accurate (I have One). Keep in mind that burn includes your BMR, the calories you'd burn by just being alive.

elphie754

I find mine to be pretty accurate as well, but I only eat 3/4 of my exercise calories back just in case.

eeejer

I find mine gives me about 30-40% more calories burned than I actually do, and this is over 2 years with stints of eating maintenance and maintaining weight so I know how off it is.

egable1

It is probably relatively accurate for that duration of time, but as zyxst pointed out, it includes your BMR. If you want the number of calories you can log in MFP, you need to subtract your BMR from those. So, for example, my BMR is about 2,200 calories per day. That is 2,200 / 24 = 91.6 calories per hour. 42 minutes is basically 2/3 of 1 hour, so that would be roughly 60 calories of BMR counted in those 643 calories. So, you could add 580 calories as exercise calories. Body weight, elevation change, fitness level, and stride all will affect the actual number of calories you burned. I created a spreadsheet which I use for logging my walking on my treadmill. I found some equations which determine calories burned based on O2 consumption of muscle moving 1kg of weight 1 meter horizontally and vertically while walking, and another based on running. Using that equation, the incline of the treadmill, the duration of the walk, and the distance, I calculate the number of meters moved horizontally and vertically and use my body weight from that day to derive the calories burned. It typically reports a number much higher than the treadmill reports (which seems to use the same equations based on 150lbs of body weight) but a fair bit lower than my MyZone heart rate chest strap monitor reports.

Running, jogging, and walking are all very different in terms of calorie burn because of the vertical weight movement component. When you walk, you are mostly just moving your body weight horizontally. When you jog, there is additional vertical movement of your body weight. When you run, there is considerable vertical movement of your body weight with each stride. All of these effects are compounded when you also have an elevation change involved. This is why heart rate monitors are so useful in determining calorie burn. By watching heart rate, you are basically already factoring in these differences. Unfortunately, they are not as accurate as the equations tend to be.

stealthq

abbietaylor1 wrote: »

Hey, so I am fairly new to using Fitbit and I just used my Fitbit surge to track my first run. I ran a slow 6.3k (in 42 minutes) and it told me that I burned 643 calories! This seems high to me and so I just wondered what your views were on this? Thanks for your thoughts!

Seems high to me, too, but it could be. Depends on your weight. For a good rule of thumb, a 150 lb person burns about 100 cals per mile (gross, so includes BMR). Speed doesn't contribute enough to matter. Elevation does, so you'd be burning more if the course were exceptionally hilly.

beastmode_kitty

Mine seems fairly accurate and I have been using mine since this past christmas.

socioseguro

zyxst wrote: »

I find mine to be accurate (I have One). Keep in mind that burn includes your BMR, the calories you'd burn by just being alive.

+1. Fitbit calorie burned number is a mix for actual activity burned plus calorie burn by existing (BMR)

abbietaylor1

Wow thanks for all the useful info - really appreciate it. I am quite heavy (182lbs) and there were a few hills (they have taken me a long time to be able to run up them so it is hard work!) so sounds like it may have been accurate - woop! Makes me feel even more motivated to run now.

abbietaylor1

abbietaylor1 wrote: »

Wow thanks for all the useful info - really appreciate it. I am quite heavy (182lbs) and there were a few hills (they have taken me a long time to be able to run up them so it is hard work!) so sounds like it may have been accurate - woop! Makes me feel even more motivated to run now.

As in a long time to train to build up my stamina to be able to get up them, rather than the hills themselves taking a long time to get up (although I'm not quick by any stretch of the imagination!)