Calorie burn

[1348gt]

The # of steps taken in a day should drive the calorie burn reported.  Yet, the calorie burn is not necessarily higher on days with more steps.  Why is that?

[Dominique]

You had 3167 steps on Feb. 25 and 14,334 steps on Mar. 2. What were your calorie burns for those two days? You should definitely see a significant difference, assuming you were wearing your Fitbit all the time.

If you look at my calorie burn and my steps for the same period (last 30 days), you can see they are directly correlated:

I had a foot injury and was resting for a week (Feb 21 to 28). During that period (step count ranging from 3300 to 7900), I had a much lower calorie burn (1879 to 2305) than usual (2600 to 3300). I'm using a Fitbit One, which I wear 24/7 (except when showering and when recharging it).

[slysam · Accepted solution]

Your Fitbit calorie burn is based on a portion of your BMR and how much and how fast you move each minute. It is possible to have a day with moderately higher steps that are taken slowly, with less intensity that results in a lower calorie burn than on days with significantly fewer steps that includes more vigorous activity. For example, I had a 15,000 step day that burned less than a typical 10,000 step day for me. The 15k step day in question was on vacation and I was spending the day browsing museums and galleries. I was moving around a lot, but it was all light activity--a few slow steps here, stop, a few more slow steps--stop. On a 10k step day that includes some vigorous activity and a reasonable amount of activity outside exercise I could burn a little more than that museum day. If you are manually logging exercise, that further complicates it because whatever you logged replaces fitbit's burn for that time period. I wouldn't expect a 3k day to trump a 12k day (unless you logged a lot of non-step activity like swimming, weights, rowing, etc). But it is possible and probably in some situations for the lower step day to burn more than a lighter intensity day that involved more steps (like maybe a couple thousand step difference). I think my museum day was a little more extreme difference than usual so that is why I mentioned it. It did have a significantly higher burn than if I were sedentary, but usually a 15k step day has a higher burn than that particular one did. But it made sense after I thought about what activity I was actually doing.

[Mary · Accepted solution]

What they said.  Or said differently, it's not the number of steps, it's the time spent at the activity detected.  If Fitbit detects you walking at 3mph for 20 mins. it assigns calories to those minutes based on the METs value of that activity, which is a multiplier of your BMR rate.  If it detects you sprinting, same.  So the steps count itself is somewhat incidental.  

[Rystmom]

Thank you Mary! Your explanation made perfect sense to me. Still learning the ins and outs of the fitbit world