How Accurate is the Fitbit Charge 2 Heart Rate Monitor?

mrswine

I've recently started using my Fitbit again, along with weighing and measuring my food. Today I worked out twice - once at an aerobics class and I went for a hike. My fitbit is adding a ton of calories to my diary - like 900+ for the hour and a half workouts plus my daily activity. So, my question is, how accurate is it? Should I trust it's exercise calories and eat those back? Or should I be conservative and eat back only some? I've been down the road of eating too little before, and don't want to end up plateauing because I'm not eating my calories back. Thoughts?

MeanderingMammal

mrswine wrote: »

Today I worked out twice - once at an aerobics class and I went for a hike.

For those activities, likely a significant over estimation.

CoachJen71

Check your dashboard data against expected heart rates and burns. I have seen my Charge2 hrm say
I was at 185bpm just walking at 3mph. Should have been way under half that. So it was saying I was burning 6 or 7 cals a minute instead of the more accurate 3 cals a minute. I have given up on using Fitbit and MFP as a NEAT system simply because not only is Fitbit wrong, it is inconsistent in its wrongness so that even making my profile height shorter has not helped.

I use the data from my loss and maintenance and roughly worked out calories for steps per day. I get fewer cals if I sleep late, more if I hike miles of hilly trails.

jonathanbcase

First, no Fitbit device is deemed a certified 'medical device', so the clinical accuracy of a Fitbit should never, ever be taken as authoritative.

Speaking from personal experience, I had a precautionary stress test a couple of years ago and was wearing my Fitbit Charge (not the Charge 2) during the test. I was watching the clinical heart monitor display and periodically checking my Fitbit at the same time. The readings were very close (within 5 bpm) of one another, and I must confess that surprised me.

Additionally, the way you wear the Fitbit (placement, strap tightness, cleanliness of the sensors, etc.) can impact the quality and reliability of the readings, so please take that into account.

Bottom line, the Fitbit heart rates should be used as an indicator, not as a clinical/medical reading. Just like the self-administered blood pressure 'chairs' that you see at the drug stores and other retail spots, they cannot and should not ever be taken as medically reliable.

MeanderingMammal

jonathanbcase wrote: »

First, no Fitbit device is deemed a certified 'medical device', so the clinical accuracy of a Fitbit should never, ever be taken as authoritative.

Speaking from personal experience, I had a precautionary stress test a couple of years ago and was wearing my Fitbit Charge (not the Charge 2) during the test. I was watching the clinical heart monitor display and periodically checking my Fitbit at the same time. The readings were very close (within 5 bpm) of one another, and I must confess that surprised me.

Additionally, the way you wear the Fitbit (placement, strap tightness, cleanliness of the sensors, etc.) can impact the quality and reliability of the readings, so please take that into account.

Bottom line, the Fitbit heart rates should be used as an indicator, not as a clinical/medical reading. Just like the self-administered blood pressure 'chairs' that you see at the drug stores and other retail spots, they cannot and should not ever be taken as medically reliable.

A reasonable point, but probably not relevant to the question asked.

The material point is that regardless of the accuracy of otherwise of HR monitoring, HR has no meaningful relationship with calories expended for the activities identified.

mrswine

Thanks all, that's what I figured. I'd like to be as accurate as possible, and don't want my progress to be effected by an inaccurate device suggesting I'm burning more, and can therefore eat more. I think I'll return my fitbit and go back to using my chest strap HRM for workout and relying on weight loss to determine if my calorie count is in the correct range for my activity level.

MeanderingMammal

An HRM is just as problematic. The issue is that HR isn't a reliable proxy.

ashley52601

I just returned my charge 2 back to the store. Unless wearing it makes you more active then you normally would I think its worthless, at least for me. After wearing it for close to a month and seeing the step count be completely off (didn't ccount steps taken while pushing a stroller or cart) flights of stairs wrong, sleep cycles wrong, etc. There was no way I could trust the data enough to do anything with it. It was just an expensive novelty item for me.

aeloine

So I have had to switch it to my nondominant hand and tell it that it was my dominant hand. It was WAAAAY overestimating before. Now seems reasonable.

sijomial

mrswine wrote: »

Thanks all, that's what I figured. I'd like to be as accurate as possible, and don't want my progress to be effected by an inaccurate device suggesting I'm burning more, and can therefore eat more. I think I'll return my fitbit and go back to using my chest strap HRM for workout and relying on weight loss to determine if my calorie count is in the correct range for my activity level.

That HRM will tell you your heart rate not calories.
Calories are units of energy remember and can't be divided into heartbeats.
Not at all suitable for hiking, If your aerobics has up and down intervals then it will most likely over-estimate.

BTW - was the 900 cals an adjustment for the difference between your entire activity and exercise versus your goal on here or was it just an estimate for the exercise?