Calories lower with Charge HR than with Flex?

segacs

I just upgraded my Fitbit Flex to a Charge HR. (Yay, Black Friday deals!) One thing I've noticed almost immediately is that I'm getting, on average, 10% fewer calories from regular daily activities than I was with my Flex. As a result, I'm getting about 100 fewer calories per day.

Has anyone else noticed this? Is it possible that the Flex was overestimating my burns from things like walking, and the HRM is correcting that overestimation? I thought the estimates from my Flex were pretty close to my real-time results, so I'm wondering if it's the Charge HR that's off?

Thoughts?

RunRachelleRun

I just upgraded to the Charge HR from the One and am getting higher burns. I went on a walk/run yesterday and wore my One, my Garmin, and my new Charge HR and got the following calorie burns:

Fitbit Charge HR: 33:49 mins, avg 147 bpm, max 173 bpm, 352 calories, 1.78 miles, 3,930 steps
Fitbit One: 34:00 mins, 332 calories, 2.09 miles, 4,001 steps
Garmin: 31:30 mins, avg 155 bpm, max 175 bpm, 302 calories, 2.08 miles

I started them all at slightly different times (had to wait for the Garmin to acquire GSP) and I forgot to set my stride length on the Charge, which means I went further than the Charge estimated, so it probably would have given me an even bigger burn had I set that.

I was worried the Charge HR would give me too high of calorie burns because I have a high working heart rate; though my resting heart rate is average to below average.

The One didn't count about 1/3 of my steps every day though; it seemed to require forward motion at a good speed before it counted anything. Things like cooking, aerobics, or anything with movement from side to side counted no steps at all for me.

It's good to know you were losing according to the results the Flex was giving you! I believe I read the Charge HR takes a couple weeks to get accurate results because it has to learn your daily averages, but I'm not sure where I read that.

segacs

Yeah, I've heard that too. I can wait and see if it levels off. I suppose it is possible that I am not burning as much as the Flex thought I was through simple walking, because I do tend to walk a lot so I suppose my body is used to it and my heart rate doesn't go up all that much. But I found that even after running up 4 flights of stairs, when I was clearly at a higher heart rate, the charge HR wasn't really reading it as that high.

Can someone explain to me the difference between "auto" and "on" for HR tracking? Is it possible that this has something to do with it?

RunRachelleRun

I read auto turns it off when it determines you aren't wearing it to save the battery, whereas on leaves it seeking all the time.

I noticed it took a while into the run to recognise the higher heart rate. I was in the 140s and it was saying 100-120, but by the end it was pretty much the same as my Garmin. I was surprised how accurate it was.

segacs

Hmmm. Yeah, well, there's definitely a discrepancy. My 3km treadmill run gave me around 190-195 calories with the Flex. Today I just ran it with the Charge HR and it gave me 151 calories for the exact same time and distance, despite registering the higher heart rate.

zdyb23456

I think the calorie burns are kind of low too. I got mine on Black Friday too
My resting heart rate seems lower than what the Jawbone Up3 would track. I think the jawbone heart rate tracking was more accurate. So that might be why the calories burned is lower since I'm assuming it factors in heart rate.

segacs

True. But it tracked the elevated heart rate during my run. It even identified the parts of the run when I was in the "peak" zone. But the calorie estimates are still quite a bit lower.

If the Charge HR is the more accurate of the two, fine, I'll just adjust my calorie intake downward. But I had found the Flex to be reasonably accurate, and I do like to eat, so...

heybales

It should take a week or two for the HR based units to start giving decent calorie burns for exercise.
Daily activity should still be step-based, so no issue there.

But Fitbit needs to determine what your resting HR is, based on history, and how often it appears you workout weekly.

You should see a change after a week or two.

segacs

I was just wondering if anyone else found it was underestimating by this amount. Most posts so far seem to suggest that people find the Charge HR overestimates burns.

And yeah, I'm going to give it another week or two and see if it adjusts.