Charge 2 accuracy

justinejacksonm

Hi I know using Fitbit it's not an exact in terms of calorie burn it should be used more as a reference or guide. I don't rely on whatever it tells me when I'm budgeting my cal's in/out, but would like to know how reliable it actually is.

What I'm wondering is what the range of accuracy may be? Like if it calculates that I burned 400 calories, to what degree of accuracy is that calculation?

Is it a bang-on, to-the-calorie number?

Is itv within a much broader range (n either direction) like could be 20 cals less/more...200.... Etc.

Not sure if I'm explaining my question well. But if it says I earned so many calories from exercise, I don't want to go eat 300 and I've really only burned 100, kind of thing.

witchaywoman81

In my experience, it’s as accurate as it can be. I tend to eat back most of my exercise calories, and it hasn’t negatively impacted my weight loss. I also have negative calorie adjustments enabled, so if I have a less active day, I don’t get as many calories.

GottaBurnEmAll

I find mine to be pretty much spot on.

But it's important to remember that fitness trackers are based on averages, and some people fall outside of norms.

The only way to know if it's accurate for you is to track results vs. what you'd have expected from the data the tracker gave you, and then adjust from there. It's pretty easy to do this, but you need to do it over a decent period of time (say, six weeks or so) to avoid the noise of fluctuations.

oat_bran

I've tracked my intake, weight and my Charge 2 TDEE estimates over many months on a spreadsheet and it's estimates appear to be spot-on. I've heard Charge 2 is one of the most accurate trackers in terms of TDEE estimates and heart rate even compared to the newer generation of fitbits.

NorthCascades

justinejacksonm wrote: »

What I'm wondering is what the range of accuracy may be? Like if it calculates that I burned 400 calories, to what degree of accuracy is that calculation?

Is it a bang-on, to-the-calorie number?

That's a smart question.

Fitbit doesn't make any promises regarding accuracy. It could say 400 kcal when you've only burned 1, and it would be operating within spec.

My fancy Garmin is off by up to 40% for bike calories, and that's using the best HR to calories algorithm available, which Fitbit doesn't use. It's always too high, never too low. ("Vanity sizing")

But the good news is you don't need to the digit accuracy to lose weight. There's plenty of margin throughout the process (food calories tend to be estimated too for most people), and you'd have to be exercising hours everyday for the error to become significant.

Finally, the way Fitbits work is consistent, even if it isn't accurate. You can work with that. If it says you burned 400 kcal when you burned 300, your logs can eventually reveal that, an you can work with it. Because it's going to use the same math tomorrow as it used today.

Fflpnari

I think mine is accurate. I went off the weekly average burn to figure out my calorie intake. Going off of those numbers I have lost weight as expected

Duck_Puddle

I find my Fitbit to be pretty reliable overall. Meaning looking at TDEE estimates from my Fitbit, compared to my food logs (I weigh my food) and my change in weight - it’s pretty close.

Where you’re going to run into problems most certainly is taking Fitbit calories burned during a workout and plopping those numbers elsewhere.

Fitbit calories burned during a workout is your total calories burned from the moment you hit start until the moment you hit stop. That number includes all the calories you burned doing the workout AND the calories you would have burned had you been sitting on the couch.

So Fitbit calories for an individual workout are always going to seem high-because Fitbit’s aren’t really intended to give you a reliable number burned for your workout specifically-but rather to estimate your calories burned 24/7/365 (for which it doesn’t matter how much of the burn during the workout period would have happened anywhay even if you weren’t working out).

If you have your Fitbit synced to mfp-this isn’t an issue because Mfp gets your TDEE from Fitbit and the calorie adjustment is based on that.

Nothing is specific to the 35th decimal place. Even your food labels are inaccurate (not every single food in the universe has a calorie value that’s a unit of 5).

So roll with it and be consistent and after 4-6 weeks, evaluate.

AnnPT77

All these devices estimate, they don't measure, calories burned.

Because they're statistical estimates, they're likely to be close for most people, off (in either direction) for some, and way off for a very few.

Furthermore, devices are likely to calorie-estimate certain kinds of activities with greater reliability vs. other kinds of activities. For example, heart rate is a bad way to estimate calories for interval workouts, because of specific aspects of heart rate behavior during that type of work.

For example, if the high intervals all are at exactly the same intensity, and the low intervals all at exactly the same lower intensity, heart rate will increase from intense interval 1 to intense interval 2, and increase further on interval 3, and so forth. While the algorithm theoretically could take that into account, how much heart rate increases over the course of the workout is going to vary based on individual fitness and other factors. Further, a fit person's heart rate will drop quickly in the slower intervals, and an unfit person's will drop much more slowly, even if both are doing exactly the same work (run/walk at the same pace, at the same body size, on the same course, for the same duration, say - which would roughly burn the same number of calories for both people). In addition, it's unusual for people to know their true maximum heart rate, so the devices use age-based estimates, which are inaccurate for a quite a large fraction of people. In that case, they may mis-estimate how hard a person is working.

But, happily, what NorthCascades said above is correct: Consistent estimates are good enough, when used in a context where one monitors calorie intake and weight results, and adjusts intake as needed to stay on course.

NorthCascades

Duck_Puddle wrote: »

Nothing is specific to the 35th decimal place. Even your food labels are inaccurate (not every single food in the universe has a calorie value that’s a unit of 5).

I always wondered how all the tortillas in the bag are 90 calories when one of them is huge and a couple are tiny.