Any fitness people in here?

"StingrayJake" (stingrayjake)
12/09/2015 at 19:58 • Filed to: Fitness

I’ve been using a Fitbit Surge to track activity and exercise for about five months now.

I’ve lost about 25 pounds in that time (would be better but I had a hiccup in November) so I don’t have a lot to complain about.

However after I shared a screenshot on Facebook of a 5-mile walk (not running just yet) I did on Thanksgiving, a friend who runs marathons commented that burning 1,000 calories (according to Fitbit) during said walk seemed really high.

I usually go for a 2-mile walk and average 3.5 mph and 130 bpm. Fitbit says I burn around 500 calories for the walk but that’s twice what a few different calorie calculators say I should be burning at 3.5 mph for the 34-36 minutes it takes me.

I’m just a little concerned that this fairly expensive devise isn’t being very accurate, which hampers me reaching my goals.

DISCUSSION (20)

AM3R shamefully returns > StingrayJake
12/09/2015 at 20:06

I got my parents both a fit bit last year, and I started using one to keep track of how much I'm moving. My mom tells me it's fairly accurate, although I only really use it as a pedometer. 10k steps a day is ideal IIRC.

DasWauto > StingrayJake
12/09/2015 at 20:13

I assume you’ve adjusted your weight on the fitbit to account for what you’ve lost?

Regardless, 1000 calories in that timeframe is definitely on the high side.

1000 Calories/hour is about what I’d be doing running or biking at a sustainable pace for an hour (~7mph or so and ~20mph respectively).

StingrayJake > AM3R shamefully returns
12/09/2015 at 20:15

Yeah and I think 30 minutes of activity is a plus in general so I’m getting there. I'm just concerned that I'm actually going over on calories occasionally.

StingrayJake > DasWauto
12/09/2015 at 20:18

Yeah I use MyFitnessPal and it syncs.

I think Fitbit factors in heart rate as well while basic calorie calculators don't. I remember when I first started walking my heart rate was upper 150s and I burned more in the same time frame.

DasWauto > StingrayJake
12/09/2015 at 20:25

It makes sense that a higher heart rate results in a higher burn rate but even so it seems high. When I’m running on a treadmill with a heart rate monitor my heart rate is 140-150 or so IIRC.

I don’t know if there is some way to adjust the fitbit down to be more in line with other calculators or if equipment and calculators I’ve used just end up low.

OPPOsaurus WRX > StingrayJake
12/09/2015 at 20:27

seems legit. i spent 15 minutes on a stationary bike and it said about 125 calories, altho I was pushing hard

OPPOsaurus WRX > StingrayJake
12/09/2015 at 20:28

see if you can find a calulator online that will give you an estimate

StingrayJake > OPPOsaurus WRX
12/09/2015 at 20:33

Yeah the online calculators say 270 calories or so for 3.5 mph over 36 minutes.

Guess I can just adjust my diet knowing Fitbit is doubling my burn.

OPPOsaurus WRX > StingrayJake
12/09/2015 at 20:42

yea after a week or so of salads you get used to it

dammit now I want some KFC

StingrayJake > OPPOsaurus WRX
12/09/2015 at 20:53

I do pretty good as is. For me it's all about portion control. Yeah I still eat bread but it all fits within my calorie budget. I avoid fried foods almost entirely. There are some good ways to eat grilled chicken.

crowmolly > StingrayJake
12/09/2015 at 21:10

If I remember correctly the FitBit uses PPG to measure heart rate- which can be anywhere from mostly accurate to wildly out to lunch. There are a lot of consumer HR devices that suffer from the same problem. If you want to train using ranges and HR for calorie burning you are better off with an EKG device like a Polar.

Be aware that the error we are talking about can be nonlinear- so if it’s off 2-4% down low it can be off 8-10%+ on the high end, or vice versa.

StingrayJake > crowmolly
12/09/2015 at 22:12

I see. So by design it's not especially accurate on heart rate and that's skewing my calorie burn.

crowmolly > StingrayJake
12/09/2015 at 22:14

I do not know the FitBit’s exact error numbers but PPG as a data collection method can be troublesome, yes.

Stephen the Canuck > StingrayJake
12/11/2015 at 11:34

My guess would be that the Fitbit is adding the calories burned from the acitvity to your resting calorie burn of just existing.

StingrayJake > Stephen the Canuck
12/11/2015 at 11:44

Well it does that anyway for total calorie burn. Are you suggesting that it’s including the automatically calculated metabolism burn in my exercise numbers? I don’t think it’s doing that but it could be possible. Even then, it would be a negligible amount compared to the exercise burn and not half of what it’s reporting.

Something that occured to me yesterday is that my neighborhood route does have some uphill sections. I wonder if it’s factoring that into the calorie burn as well because it does track barametric pressure to track floors I’ve climbed.

Stephen the Canuck > StingrayJake
12/11/2015 at 11:54

It was a thought. Thinking about it further does make it seem unlikely. I’ve used a Misfit Shine and I found that it wasn’t always accurate for measure stuff if it didn’t move my arms much (wore it on my wrist). I also found the step counter app on my phone would throw in extra steps quite often. Maybe the fitbit is doing something similar?

Uphills would add some more calorie burning compared to flat ground. But then it probably wouldn’t add enough to make the count seem really high.

StingrayJake > Stephen the Canuck
12/11/2015 at 11:57

Exactly. I like having the time and GPS of the Fitbit but ultimately I’ve decided to adjust my diet based on what I’m seeing elsewhere for calorie burn. I just know I can’t really trust the heart rate now.

Stephen the Canuck > StingrayJake
12/11/2015 at 12:00

The Shine I had was basically for tracking distance and steps, no heart rate or anything fancy. It’s neat to see those numbers spelled out.

For adjusting diet, I’d want the most accurate measuring device I can reasonably find. A quick google search found a reddit post where a person went from a Fitbit Charge to a Charger HR and the HR one was measuring 600-850 higher calories burned in a day for the same activities.

StingrayJake > Stephen the Canuck
12/11/2015 at 12:25

Yeah has to be because the Fitbits that are capable of tracking heat rate are factoring said heart rate into calorie burn. Unfortunately, as somebody else posted here, Fitbit’s method of measuring heart rate is a bit flawed.

That actually explains why I wasn’t losing two pounds a week when my Fitbit showed that I was hitting my intake/burn target every day.

Stephen the Canuck > StingrayJake
12/11/2015 at 12:31

Hopefully it’ll work out for you. If you know what the numbers should be then you can adjust.

I stopped wearing my tracker. I’ve lost around 10 pounds since July by actually going to a gym and working out and trying to eat healthier.