Fitbit: Just for step calories, or can I leave it on for workouts?

Rockmama1111

My activity level is set to sedentary and I use the Fitbit calories MFP grants as incentive to get more steps. I generally eat all the extra calories. I’ve analyzed 16 weeks of data (Fitbit and MFP) and I’m satisfied that the additional calorie estimates are close (enough). Until now, my only activity is walking/hiking.

I’d like to gradually add more. I’ll probably start with toning with light weights, but I’m considering taking a yoga class and have also considered more aerobic-dance-type classes.

If I just wear my Fitbit during any other activity, can I be reasonably comfortable that the extra calories are still fairly accurate? Or should I remove my Fitbit during a dedicated workout and log that workout separately? I’m wondering if since Fitbit tracks my heart rate, it’s the best estimate of what I’m burning during a given activity. Is this true?

I’m curious to see how others do it, and your reasoning for why.

JaysFan82

I keep them separate. I use a basic pedometer not a Fit bit. I only wear it for my two minute warm up walk. I turn it off while I'm running and lifting weights.

Retroguy2000

Of the activites you mention, it may be accurate enough for walking, dance and yoga, but it may inflate estimates for weights. I've read you can tell the app and device that you're doing a weights session, so it tunes its tracking and estimate during that time, is that still true?

The thing is, not using it will be inaccurate in different ways too, so will that be better or worse? e.g. I don't have a tracker, and for my weights I use an estimate of 3.5 MET, i.e. about 2.5 additional MET. However, I see estimates as high as 6 MET for vigorous weights. I guess I'm at 4 maybe, and choose 3.5 to be conservative. For me, 1 MET is about 100 calories, so ny guess could be accurate, or under by 100-200. I suspect under, based on my tracking of my weight with weekly net calories including this estimate.

AnnPT77

I agree that Fitbit may overestimate strength training calories, maybe is more likely to be accurate for other modes (details matter).

Honestly, since you've shown yourself that you can check your actual progress (averaged over multiple weeks, of course) against what your Fitbit and MFP negotiate, I'd encourage you to keep doing that as you add new activities, and see if the Fitbit adjustment continues to give you a reasonable calorie goal to make the healthy, moderate progress that you're shooting for.

Yeah, from a theoretical standpoint it'll be over on some estimates, but maybe under on others. (Some people think the devices are only capable of overestimating. I don't think that, from personal experience. They can under- or over- estimate.) What matters if you have a device synched to MFP is how all that averages out, and that's going to be as unique as the combination of things you personally do.

Yeah, if your Fitbit model lets it tell you what type of workout you're doing when you do it (strength training vs. walking, aerobics, yoga, or whatever), do use that feature. That can help the device be smarter about estimates.

If you want to compare for strength training specifically, a rough comparator would be to look at the calories Fitbit gives you for a regular reps/sets weight workout, then look at what you'd get if you logged it in MFP's cardiovascular section as "Strength training (weight lifting, weight training)" (Use the whole time period, including normal between-set rests.) Personally, I wouldn't worry if Fitbit's estimate is off by a small percent of your total daily burn, even if the raw number seems big-ish.

But I think doing that is pretty academic, as a practical thing. What really matters is the averages over time, for everything, not just that one number. If you can achieve your goals by synching your Fitbit, maybe adjusting a little bit on the total if that seems necessary, that seems much simpler to me than messing around with more logging and details.

Yes, it's not "accurate", but all of this is just estimates - base calorie estimate, activity level, exercise, even food labels aren't exact. Getting to a good-enough result via a manageable practical process is a good strategy.

Just my opinion, though . . . and I'm saying that as someone who likes getting into arcane details about estimating exercise calories.

Rockmama1111

Thanks for responding! I explored the Fitbit app and there is indeed a spot to label a specific stretch of activity as something other than stepping. (No strength training or yoga option though.) It also calculates a calorie burn. I’ll test that feature and see how it calculates and transfers to MFP.

Realistically, any strength or yoga I do won’t be too strenuous. Reps with hand weights might inflate step count, so I’ll keep an eye on it.

AnnPT77

Rockmama1111 wrote: »

Thanks for responding! I explored the Fitbit app and there is indeed a spot to label a specific stretch of activity as something other than stepping. (No strength training or yoga option though.) It also calculates a calorie burn. I’ll test that feature and see how it calculates and transfers to MFP.

Realistically, any strength or yoga I do won’t be too strenuous. Reps with hand weights might inflate step count, so I’ll keep an eye on it.

The big deal with strength training is that lifting can raise heart rate for reasons that have nothing to do with increased oxygen demand, and it's oxygen demand that correlates reasonably with calorie burn. Heartbeats are just an indirect proxy that's easier to measure.

For example, some kinds of strain can raise heart rate, and so can (loose description) the kind of intra-body pressure that happens when controlling breathing, or holding weight overhead. A HRM-based estimate may mis-estimate strength calorie burn because of things like that. Some trackers, if they know you're strength training, will take that into account, IMU. If they don't know, they can't (and I don't know that all brands/models are that smart in the first place). Some of those kinds of things can happen with some types of yoga, maybe, too, but strength training can be kind of an extreme in that way.

Decent odds your all-day average won't be too distorted IMO, as long as it's been working well for you in other contexts. It's an experiment you can run, easily, anyway.

Antiopelle

I keep my Fitbit on day and night and I try to eat back about half the added exercise cals it transfers to MFP. That works for me and it gives me the perfect data for my excel where I track cals eaten (net and total from MFP) and cals burned (Fitbit). I do lift 2 to 3 times a week but I don't track it as a specific workout. The raised HR for 30 minutes doesn't make that much difference in my case.
On a weekly basis I deduct the total cals in from the cals out and check it against my average weight of that week. For me it shows pretty clearly that about 3.500 cals in deficit is a pound lost - yes, it's magic !!
Try that for a few weeks and see if it adds up. If not, correct a bit either way.